Secondary battery

Abstract

To provide high-capacity anode active material having excellent cycle and rate characteristics, and also to provide a secondary battery incorporating this anode active material and electronic equipment incorporating this secondary battery.SOLUTION: Negative electrode active material is made by: mixing nanosilicon with a solid electrolyte having lithium, titanium, phosphorus, and oxygen thereby obtaining mixture and further adding graphene oxide to the mixture; then reducing graphene oxide included in the mixture using ethanol in which ascorbic acid and lithium hydroxide hydrate are dissolved. The solid electrolyte may further include aluminum.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a negative electrode active material, a secondary battery, and an electronic device.

[0002] Note that one embodiment of the present invention is not limited to the above technical fields. The technical field relates to an article, a method, or a manufacturing method. is a process, machine, manufacture, or composition of matter. Therefore, one aspect of the present invention disclosed in this specification more specifically relates to The technical fields of the present invention include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, power storage devices, and imaging devices. Device, storage device, processor, electronic device, system, driving method thereof, and manufacturing method thereof Examples include methods for detecting the presence of fluorine, and methods for inspecting the same. [Background technology]

[0003] In recent years, various types of energy storage devices have become available, including lithium-ion secondary batteries, lithium-ion capacitors, and air batteries. The development of lithium-ion batteries, which have high output and high energy density, is particularly active. Secondary batteries are used in mobile phones such as smartphones and portable information devices such as laptop computers. information terminals, portable music players, digital cameras, medical equipment, or hybrid vehicles (HEV ), electric vehicles (EV), or plug-in hybrid vehicles (PHEV), etc. Demand for lean energy vehicles and other technologies is expanding rapidly along with the development of the semiconductor industry. It has become an essential source of energy for modern society.

[0004] The characteristics required for lithium-ion secondary batteries are higher energy density, These include improved cycle characteristics, safety in various operating environments, and improved long-term reliability.

[0005] Therefore, we aimed to improve the cycle characteristics and capacity of lithium-ion secondary batteries by developing a positive electrode Improvements to the active material have been investigated (Patent Document 1 and Non-Patent Document 1). Research into the crystal structure is also being conducted (Non-Patent Documents 2 to 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-164758 [Non-patent literature]

[0007] [Non-Patent Document 1] Jae-Hyun Shim et al, “Characterization of Spinel LixCo2O4·CoatedLiCoO2 Prepared with Post-Thermal Treatment as a Cathode Material for Lithium Ion Batteries”, CHEMISTRY OF MATERIALS, 2015, 27, p.3273-3279 [Non-patent document 2] Toyoki Okumura et al, “Correlation of lithium ion distribution and X-ray absorption near-edge structure in 03-and 02·lithium cobalt oxides from first-principle calculation”, Journal of Materials Chemistry, 2012, 22, p.17340-17348 [Non-patent document 3] Motohashi, T. et al, “Electronic phase diagram of the layered cobalt oxide system LixCoO2(0.0≦x≦1.0)”, Physical Review B, 80(16);165114 [Non-patent document 4] Zhaohui Chen et al, “Staging Phase Transitions in LixCoO2, Journal of The Electrochemical Society, 2002, 149(12) A1604-A1609 Summary of the Invention [Problem to be solved by the invention]

[0008] In order to increase the discharge capacity of a lithium-ion secondary battery, the electrodes of the secondary battery Therefore, it is preferable to use a material with a large theoretical capacity. In particular, the negative electrode material is preferably, for example, Silicon (Si) can be used. Theoretical capacity of silicon for lithium ions is 3.6 x 10 3 mA / g, which is the theoretical capacity ( 3.7×10 2 mA / g).

[0009] However, materials such as silicon that are alloyed with lithium absorb more carrier ions. This means that the expansion and contraction caused by the absorption and release of carrier ions during the charge and discharge cycles is large. Therefore, the contact area between the active material and the conductive additive, the contact area between the active materials, and the contact area between the active material and the current collector are The area may become smaller and the conductive path may be damaged. However, the discharge capacity decreases with the charge / discharge cycle. The lithium ion secondary battery is deformed or broken down, peeled off from the current collector, or pulverized. It becomes difficult to maintain the pond's function.

[0010] One aspect of the present invention provides a negative electrode active material that is resistant to damage even after repeated charge-discharge cycles. Another object of one embodiment of the present invention is to use the semiconductor device in a lithium-ion secondary battery. The object of the present invention is to provide a negative electrode active material that suppresses the decrease in capacity during charge / discharge cycles. Another object of one embodiment of the present invention is to provide a high-capacity secondary battery. Another object of one embodiment of the present invention is to provide a secondary battery with excellent charge-discharge characteristics. Another aspect of the present invention is to provide a secondary battery with high safety and / or reliability. This is one of the challenges.

[0011] Another object of one embodiment of the present invention is to provide a method for manufacturing a novel negative electrode active material. do.

[0012] Note that the problems of one embodiment of the present invention are not limited to the above-listed problems. This does not preclude the existence of other problems. Problems not mentioned in this section are problems that a person skilled in the art would be able to solve by understanding the specification or can be derived from the descriptions in the drawings, etc., and can be extracted appropriately from these descriptions. One aspect of the present invention is to achieve at least one of the above-listed objects and other objects. One aspect of the present invention is to solve the above-listed problems and other problems. You don't need to solve all of them. [Means for solving the problem]

[0013] (1) One embodiment of the present invention provides a negative electrode active material including particles, a solid electrolyte, and a graphene compound. The particles contain silicon, and the solid electrolyte contains lithium, titanium, phosphorus, and oxygen. It is a negative electrode active material.

[0014] (2) In addition, one aspect of the present invention is the above-mentioned (1) in which the solid electrolyte contains aluminum. The negative electrode active material contains

[0015] (3) In addition, one aspect of the present invention is the above-mentioned (1) or (2) configuration, wherein the primary particle of the particle The particle size of the negative electrode active material is 10 nm or more and 100 nm or less.

[0016] (4) In addition, one aspect of the present invention is a method for manufacturing a semiconductor device according to any one of the above (1) to (3), wherein the graph The graphene compound is a negative electrode active material containing graphene oxide.

[0017] (5) Furthermore, one aspect of the present invention is a method for manufacturing a semiconductor device according to any one of the above (1) to (4), wherein the semiconductor device further comprises: The graphene compound is a negative electrode active material having reduced graphene oxide.

[0018] (6) In addition, one aspect of the present invention is a two-component negative electrode active material having any one of the above (1) to (5). Next is the battery.

[0019] (7) Another embodiment of the present invention is an electronic device including the secondary battery described in (6). [Effects of the Invention]

[0020] According to one aspect of the present invention, a negative electrode active material that is resistant to damage even after repeated charge / discharge cycles is provided. According to one embodiment of the present invention, a lithium ion secondary battery can be used. This makes it possible to provide a negative electrode active material that suppresses the decrease in capacity during charge-discharge cycles. According to one embodiment of the present invention, a high-capacity secondary battery can be provided. According to one embodiment of the present invention, a secondary battery with excellent charge and discharge characteristics can be provided. According to one embodiment of the present invention, a secondary battery with high safety and / or reliability can be provided. Cut.

[0021] According to one embodiment of the present invention, a method for manufacturing a novel negative electrode active material can be provided. .

[0022] The effects of one embodiment of the present invention are not limited to the effects listed above. This does not preclude the existence of other effects. The effects not mentioned in this section are effects that a person skilled in the art would be able to understand by noticing the description. It can be derived from the descriptions in the documents or drawings, etc., and can be extracted appropriately from these descriptions. It should be noted that one aspect of the present invention has at least one of the effects listed above and other effects. Therefore, one aspect of the present invention is to provide the above-listed effects. It may not have any effect. [Brief explanation of the drawings]

[0023] [Figure 1] 1A and 1B are schematic diagrams illustrating a negative electrode and a negative electrode active material. [Figure 2] A diagram explaining the crystal structure of LTPO. [Figure 3] 1A to 1C are diagrams illustrating an example of a method for producing a solid electrolyte. [Figure 4] 1A to 1C illustrate an example of a method for manufacturing a negative electrode active material. [Figure 5]FIG. 2 is a diagram illustrating a method for charging a secondary battery. [Figure 6] FIG. 2 is a diagram illustrating a method for charging a secondary battery. [Figure 7] FIG. 2 is a diagram illustrating a method of discharging a secondary battery. [Figure 8] FIG. 2 is a diagram illustrating a coin-type secondary battery. [Figure 9] FIG. 2 is a diagram illustrating a cylindrical secondary battery. [Figure 10] FIG. 1 is a diagram illustrating a solid-state battery. [Figure 11] 1A to 1C illustrate examples of electronic devices. [Figure 12] 1A to 1C illustrate examples of electronic devices. [Figure 13] FIG. 1 is a diagram illustrating an example of a moving object. [Figure 14] 1 shows an SEM image and SEM-EDX analysis results of a negative electrode active material prepared by the method described in the Examples. [Figure 15] FIG. 2 shows an XRD pattern of a negative electrode active material prepared by the method described in the Examples. [Figure 16] FIG. 2 shows an XRD pattern of a negative electrode active material prepared by the method described in the Examples. [Figure 17] FIG. 1 shows the cycle characteristics of a test cell described in an example. [Figure 18] FIG. 10 is a graph showing the rate characteristics of a test cell described in an example. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and it is understood by those skilled in the art that various modifications may be made to the modes and details thereof. Furthermore, the present invention should not be construed as being limited to the description of the following embodiments. It is not something that is done.

[0025] In this specification, the theoretical capacity of the positive electrode active material is the intercalation and deintercalation capacity of the positive electrode active material. This refers to the amount of electricity when all lithium is removed. For example, the theoretical capacity of LiCoO2 is 274m Ah / g, the theoretical capacity of LiNiO2 is 274mAh / g, and the theoretical capacity of LiMn2O4 is 1 It is 48mAh / g.

[0026] In this specification and the like, the theoretical capacity of the negative electrode active material refers to the capacity when all of the intercalable and deintercalable lithium is present. This refers to the amount of electricity inserted into the negative electrode active material. For example, the theoretical capacity of Si is 4200mAh / g, and the theoretical capacity of graphite is 372 mAh / g.

[0027] In this specification and the like, it is also understood that all of the intercalable and deintercalable lithium is intercalated into the positive electrode active material. The charge depth when all intercalable lithium is deintercalated into the positive electrode active material is 0. Let the depth be 1.

[0028] In the present specification and the like, it is intended to mean that all of the intercalable and deintercalable lithium contained in the negative electrode active material is intercalated. The depth of charge when the negative electrode active material is fully intercalated and deintercalated is defined as 1, and the depth of charge when the negative electrode active material is fully intercalated and deintercalated is defined as 2. The charge depth at this time is considered to be 0.

[0029] In this specification, charging refers to transferring lithium ions from the positive electrode to the negative electrode inside the battery. In addition, the positive electrode active material is the one that releases lithium ions. This process, or in the case of a negative electrode active material, the insertion of lithium ions, is called charging.

[0030] Similarly, discharging refers to the movement of lithium ions from the negative electrode to the positive electrode inside the battery. In addition, the positive electrode active material is referred to as a material for inserting lithium ions, or the negative electrode For active materials, the process of releasing lithium ions is called discharging.

[0031] (Embodiment 1) In this embodiment, a negative electrode that can be used in a secondary battery, which is one embodiment of the present invention, The negative electrode active material layer of the negative electrode and the negative electrode active material contained in the negative electrode active material layer will be described.

[0032] FIG. 1(A) is a bird's-eye view of the negative electrode, and FIG. 1(B) is a cross-sectional view of the area enclosed by the dashed line in FIG. 1(A). The negative electrode 100 is provided with a negative electrode active material layer 102 in contact with a negative electrode current collector 101. 1(A) and 1(B), the negative electrode active material layer 10 is formed on both sides of the negative electrode current collector 101. 2 is provided on one side of the negative electrode current collector 101, but the negative electrode active material layer 102 is provided on only one side of the negative electrode current collector 101. It's fine.

[0033] FIG. 1(C) is a cross-sectional view of a negative electrode active material layer 102 having particles 103 and a solid electrolyte 104. The particles 103 are surrounded by a solid electrolyte 104. 2 may contain a conductive additive and / or a binder.

[0034] The particles 103 and the solid electrolyte 104 function as an active material. This refers to a substance that is involved in the insertion and desorption of certain ions. When making the negative electrode, which will be explained later, particles 1 03 is a mixture of solid electrolyte 104 and other materials such as solvents as an active material layer. It is formed on a current collector. Therefore, the active material and the active material layer are distinguished from each other.

[0035] The negative electrode current collector 101 is made of a material selected from the group consisting of gold, platinum, zinc, iron, copper, titanium, tantalum, manganese, and the like. Metals and their alloys (such as stainless steel) have high conductivity and are suitable for lithium ion carriers. Materials that do not alloy with silicon can be used. It may be formed of a metal element that forms a silicide by reacting with silicon. The group elements are zirconium, titanium, hafnium, vanadium, niobium, tantalum, Chromium, molybdenum, tungsten, cobalt, nickel, etc. The negative electrode current collector 101 is , foil, plate (sheet), mesh, cylinder, coil, punched metal, expanded The negative electrode current collector 101 may have a thickness of, for example, 5 mm. The thickness is preferably 8 μm to 15 μm. It is preferable that the negative electrode current collector 101 has a thickness of 5 μm or more over the entire area, for example. The thickness is preferably 30 μm or less, and more preferably 8 μm or more and 15 μm or less. However, one embodiment of the present invention is not limited thereto. For example, the negative electrode current collector 101 may be formed of at least At least in part, the thickness is 5 μm or more and 30 μm or less, more preferably 8 μm or less. Alternatively, the negative electrode current collector 101 may have a region having a diameter of 1 μm or more and 15 μm or less. In the negative electrode current collector 101, the thickness is 5 μm or more and 30 μm or less in 50% or more of the region. More preferably, it has a region with a thickness of 8 μm or more and 15 μm or less.

[0036] The negative electrode active material layer 102 described in this embodiment uses silicon as the particles 103. The solid electrolyte 104 is lithium titanium phosphate (hereinafter referred to as LTPO) or titanium phosphate. This material uses lithium aluminum tantalum (hereinafter referred to as LTAP). As shown in (D), the negative electrode active material layer 102 is made of graphene, graphene oxide (GO:Gr RGO (a compound obtained by reducing GO), multi-graphene, and RGO (a compound obtained by reducing GO) The material 105 may include at least one selected from the group consisting of the above-mentioned materials. In literature, LTPO and LATP are collectively referred to as lithium conductive ceramics, and GO, multi-graphene, and RGO are collectively referred to as graphene compounds.

[0037] The size of silicon as a primary particle is generally between 10 nm and 100 nm. This is because the size of silicon is greater than 100 nm. This is because the battery may be damaged by expansion and contraction during charging and discharging. The size is preferably approximately 8 μm or more and 12 μm or less.

[0038] In this specification, the term "primary particles" refers to particles that are not aggregated together. A primary particle can be said to be an aggregate of atoms that are continuously connected by bonds between atoms. Therefore, primary particles may be monocrystalline, polycrystalline, amorphous, etc. By using a scanning electron microscope (SEM) on the particles, clear rings of primary particles can be observed. It may be possible to observe the periphery.

[0039] In this specification and the like, secondary particles refer to particles formed by aggregation of primary particles due to intermolecular forces or the like. Also, particles that have been sintered to the extent that the shape of each primary particle can be observed are also referred to as secondary particles. Secondary particles are sometimes called "secondary particles." Therefore, secondary particles are particles that are agglomerated from primary particles. In addition, if a scanning electron microscope or the like is used to examine the secondary particles, By this method, it may be possible to observe the aggregation of primary particles and / or voids. Secondary particles can also be considered to be composed of two or more primary particles of different solid substances. good.

[0040] As secondary particles composed of a lithium-conductive ceramic and silicon, it is preferably sized generally 8 μm or more and 12 μm or less. This is because when the size of the lithium-conductive ceramic is less than 8 μm, the particles may aggregate and the particles may not disperse. Particularly, in the negative electrode active material layer having a lithium-conductive ceramic and silicon, if the particles of the lithium-conductive ceramic aggregate, it becomes impossible to prevent the deterioration of silicon due to repeated charge and discharge. Also, if the particles do not disperse, coating on the negative electrode current collector 101 cannot be done well, and when using such a negative electrode, abnormalities such as short circuits may occur during charge and discharge.

[0041] Fig. 2 shows the crystal structure of LTPO. LTPO is a NASICON-type compound having a structure of space group R-3cH. As shown in Fig. 2, LTPO has an octahedral structure in which oxygen (O) is coordinated to titanium (Ti) at 6 coordination, and a tetrahedral structure in which oxygen is coordinated to phosphorus (P) at 4 coordination. Also, the oxygen coordinated to each of titanium and phosphorus shares with each other to form the octahedral structure and the tetrahedral structure.

[0042] On the other hand, LATP can be formed by substituting a part of the titanium sites shown in Fig. 2 with aluminum (not shown). By substituting a part of the titanium sites of LTPO with aluminum to form LATP, the electrical conductivity can be increased.

[0043] <Example of method for producing LTPO>[ Here, an example of the method for producing LTPO contained in the negative electrode active material of one aspect of the present invention will be described. ​​​​​​​​​The procedure for manufacturing LTPO is simply illustrated in FIG. There are.

[0044] [Step S01: Preparation of raw materials] First, a lithium source, a titanium source, and a phosphorus source are used as starting materials for producing LTPO. As the lithium source, for example, lithium carbonate (Li2CO3) is preferably used. It is preferable to use titanium oxide (TiO2) as the titanium source. As the phosphorus source, ammonium hydrogen phosphate (NH4H2PO4) is preferably used. In this embodiment, lithium carbonate, titanium oxide, and ammonium hydrogen phosphate are mixed in a stoichiometric ratio. This will be explained assuming that the following is prepared.

[0045] [Step S02: Mixing of starting materials] Next, the prepared raw materials are mixed. For example, a pulverizer can be used for the mixing. By using a crusher, the materials can be mixed while also being crushed. When using a ball mill or bead mill, the material, size, and By adjusting the mass of the media, the rotation speed of the container containing the raw material, the processing time, etc., the desired In some cases, a mixture having a particle size of 10 ... For example, it is preferable to use zirconia balls. After mixing, the mixture is sieved using a desired sieve. It is best to separate the media from the public.

[0046] When mixing with a grinder, the raw materials are prepared by a wet method using ethanol, When it is preferable to add and mix an organic solvent such as acetone or a liquid such as water to form a slurry (Note that in FIG. 3(A), liquids such as organic solvents and water are used in the wet method.) In this case, after mixing, the slurry is sieved using a sieve with the desired openings. Remove the media contained in the container and use a laboratory hot plate or similar device to remove the media. Preferably, the liquid is evaporated from the removed slurry to obtain a mixture. After the liquid has evaporated, the slurry and the media are separated using a sieve with the desired openings. A method of obtaining a mixture by the above method may also be used.

[0047] In this specification, the term "pulverizer" refers to, for example, a ball mill, a bead mill, a jet mill, etc. In addition, the pulverizer described in this specification is not limited to one type of pulverizer. For example, a crusher that performs crushing in two or more different steps. When performing the above steps, the pulverization treatments in the respective steps may be performed using different pulverizers. For example, if multiple grinding processes are performed in one process, the grinder is changed for each grinding process. That's fine.

[0048] [Step S03: Pre-baking] Next, in step S02, the mixed material is heated. This step is a preliminary baking or first baking step. The temperature for pre-baking is usually between 200°C and 600°C. Preferably, the calcination time is 2 hours or more and 20 hours or less. The composition is preferably carried out in a nitrogen atmosphere and / or a dry atmosphere.

[0049] [Step S04: Pre-crushing] The fired product produced in step S03 is crushed in a mortar. This step is a preliminary crushing or first crushing step. Furthermore, the crushed fired material is crushed further into finer pieces using a grinder. When a ball mill or a bead mill is used as the grinding machine, the media may be, for example, For example, it is preferable to use zirconia balls. The comminution when using a crusher shall refer to the description in Step S02. When comminuting wet, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it. Refer to the description of Step S02. When comminuting wet, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it. For example, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it.

[0050] [Step S05: Main firing] In this step, the material comminuted in Step S04 is heated. This step may be referred to as main firing or secondary heating. The temperature of the main firing is preferably 800 °C or higher and 1100 °C or lower, and the time of the main firing is preferably 2 hours or longer and 20 hours or shorter. In this step, the material comminuted in Step S04 is heated. This step may be referred to as main firing or secondary heating. The temperature of the main firing is preferably 800 °C or higher and 1100 °C or lower, and the time of the main firing is preferably 2 hours or longer and 20 hours or shorter. Preferably, it is carried out at 800 °C or higher and 1100 °C or lower, and the time of the main firing is preferably 2 hours or longer and 20 hours or shorter. Furthermore, the main firing is preferably carried out in a nitrogen atmosphere and / or a dry atmosphere.

[0051] [Step S06: Final comminution and recovery] Finally, the fired product produced in Step S05 is comminuted in a mortar. This step may be referred to as final comminution or secondary comminution. Furthermore, the comminuted fired product may be comminuted more finely using a crusher. When using a ball mill or a bead mill as the crusher, it is preferable to use, for example, zirconia balls as the media. The comminution when using a ball mill or a bead mill shall refer to the description in Step S02. When comminuting wet, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it. In this step, the comminuted product becomes LTPO. Finally, the fired product produced in Step S05 is comminuted in a mortar. This step may be referred to as final comminution or secondary comminution. Furthermore, the comminuted fired product may be comminuted more finely using a crusher. When using a ball mill or a bead mill as the crusher, it is preferable to use, for example, zirconia balls as the media. The comminution when using a ball mill or a bead mill shall refer to the description in Step S02. When comminuting wet, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it. Finally, the fired product produced in Step S05 is comminuted in a mortar. This step may be referred to as final comminution or secondary comminution. Furthermore, the comminuted fired product may be comminuted more finely using a crusher. When using a ball mill or a bead mill as the crusher, it is preferable to use, for example, zirconia balls as the media. The comminution when using a ball mill or a bead mill shall refer to the description in Step S02. When comminuting wet, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it. When using a ball mill or a bead mill as the crusher, it is preferable to use, for example, zirconia balls as the media. The comminution when using a ball mill or a bead mill shall refer to the description in Step S02. When comminuting wet, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it. When comminuting wet, it is preferable to add an organic solvent such as ethanol or acetone to the fired product and then comminute it. In this step, the comminuted product becomes LTPO.

[0052] LTPO can be produced according to the above production example.

[0053] [Example of method for producing LATP] Next, an example of a method for producing LATP contained in the negative electrode active material according to one aspect of the present invention will be described. The procedure for preparing LATP is shown in simple terms in Figure 3(B). .

[0054] As a starting material for producing LATP contained in the negative electrode active material of one embodiment of the present invention, A lithium source, a titanium source, a phosphorus source, and an aluminum source are prepared. For each phosphorus source, the content of the LTPO raw material preparation in step S01 above is As an aluminum source, for example, aluminum oxide (Al2O3) In this embodiment, aluminum oxide is prepared in a stoichiometric ratio. After preparing the materials for making LATP, the above-mentioned method for making LTPO is explained. By performing the same procedures as steps S02 to S06 of the manufacturing method, the LATP can be produced.

[0055] <Example of mixing with silicone> Here, we will explain an example of a method for mixing silicon with either LTPO or LATP. The procedure for mixing silicon into either LTPO or LATP is as shown in Figure 4. This corresponds to steps S11 to S14.

[0056] [Step S11: Crushing and Mixing] One of LTPO or LATP produced by the above-mentioned production method example, and silicon; The silicon is preferably in the form of nanoparticles (for example, nanoparticle silicon). Silicon is sometimes called nanosilicon.) For mixing, a grinder can be used, for example. When a ball mill or a bead mill is used as the grinding machine, the media can be, for example, It is preferable to use zirconia balls. It is possible to crush both ATP and silicon. The particle size of the PET should be approximately the same as that of the LTPO or LATPO particles. It is preferable to use a ball mill or a bead mill for crushing. Please refer to the explanation above. When using the wet method, either LTPO or LATP and It is preferable to carry out the crushing and mixing using a slurry prepared by adding acetone to a mixture of silicon and the like. After the slurry is crushed and mixed by the wet method, it is passed through a sieve with a desired mesh size. The media is removed from the slurry using a laboratory hot plate or the like. By removing the acetone, the mixture of either LTPO or LATP with the silicon was You can get things.

[0057] [Step S12: Tableting] In the mixture obtained in step S11, either LTPO or LATP and silico In order to promote sintering with the fluorine, the mixture was molded using a tablet press or the like.

[0058] [Step S13: Firing] In this step, the molded product produced in step S12 is heated. The firing temperature is It is preferable to perform the firing at 400°C or higher and 1100°C or lower, and the firing time is 2 hours or higher and 20 hours or lower. Furthermore, the firing is preferably carried out in a nitrogen atmosphere and / or a dry atmosphere. is preferred.

[0059] [Step S14: Crushing and Recovery] Finally, the fired product prepared in step S13 is crushed in a mortar. After crushing, the fired product is crushed into pieces of a predetermined size. In order to recover only the calcined product, it is preferable to sieve the calcined product.

[0060] By the above steps S11 to S14, a mixture of one of LTPO or LATP and silicon can be prepared. In this specification, etc., a mixture of LTPO and silicon is described as the first mixture, and a mixture of LATP and silicon is described as the second mixture.

[0061] <Example of RGO coating method> A graphene compound may be further added to the first mixture or the second mixture. As the graphene compound, for example, GO, multi-graphene, RGO, etc. can be used. Here, an example of the method for further coating RGO on the first mixture or the second mixture will be described. The said method example corresponds to steps S21 to S29 in FIG. 4.

[0062] [Step S21: Preparation of raw materials] Prepare an appropriate amount of GO and one of the first mixture or the second mixture prepared by the previous preparation method example.

[0063] [Step S22: Stirring] Add water to the GO prepared in step S21 and stir with a mixer. The addition and stirring of water are preferably repeated several times.

[0064] [Step S23: Kneading] Next, add the GO stirred in step S22 to one of the first mixture or the second mixture prepared in step S21, and knead with a mixer.

[0065] [Step S24: First evaporation] In this step, heat treatment or the like is performed on the kneaded mixture to remove the moisture contained in the mixture. This step may be referred to as the first evaporation. ​​​​​​​​​

[0066] [Step S25: Crushing] The mixture prepared in step S24 is crushed in a mortar. After crushing, the mixture is crushed into pieces of a predetermined size. Preferably, the mixture is sieved to recover only the puree.

[0067] [Step S26: Chemical reduction] Next, the GO contained in the crushed mixture is reduced to RGO using a reducing agent. As the reducing agent, for example, ascorbic acid can be used. After reduction, or an organic solvent such as ethanol or acetone, and then washed and filtered to obtain a mixture. It is preferable to remove the reducing agent from the

[0068] In addition, to promote the reduction reaction, not only chemical reduction with ascorbic acid but also thermal reduction was performed. The thermal reduction will be explained later in step S28.

[0069] [Step S27: Second evaporation] In this step, the mixture reduced in step S26 is subjected to a heat treatment to The water and / or organic solvent contained in the mixture is removed. The temperature of the heat treatment is determined based on the The temperature can be determined appropriately depending on the amount of water and / or organic solvent contained. This is sometimes called second evaporation.

[0070] [Step S28: Thermal reduction] In addition to the chemical reduction performed in step S26, the GO contained in the crushed mixture If you want to accelerate the reduction reaction of GO, you can perform thermal reduction in this step. In this case, the mixture obtained in step 27 is heated in a vacuum at 200°C or higher and 300°C or lower for 8 hours. It is preferable to carry out heating under the conditions of 100 to 12 hours. This step can be performed in combination with the second evaporation of step S27. The contained GO may be entirely reduced, or partly reduced and the remaining part may be It does not have to be reduced.

[0071] [Step S29: Crushing and Recovery] The mixture prepared in step S28 is crushed in a mortar. After crushing, the mixture is crushed into pieces of a predetermined size. Preferably, the mixture is sieved to recover only the puree.

[0072] The first mixture coated with RGO by the above steps S21 to S29 can be obtained. The second mixture coated with RGO can be obtained.

[0073] <Example of negative electrode manufacturing method> Next, a silicon substrate is bonded to either LTPO or LATP, which can be prepared by the above method. The negative electrode 10 is formed as a negative electrode active material layer 102 by a mixture of the above or the mixture coated with RGO. An example of a method for producing 0 will be described.

[0074] First, a solvent and / or a binder is added to the mixture prepared by the above method. The mixing ratio may be adjusted appropriately depending on the desired battery characteristics. .

[0075] The solvent may be a liquid in which the raw material does not dissolve but in which the raw material disperses. The solvent is preferably a polar solvent, for example, water, methanol, ethanol, acetonitrile, or the like. tetrahydrofuran (THF), dimethylformamide (DMF), N-methyl-2 -pyrrolidone (NMP) and dimethyl sulfoxide (DMSO), either one or both A mixture of the above can be used.

[0076] In addition, a binder with high heat resistance, such as polyimide, is used as the binder. The material mixed in this mixing step is a precursor of polyimide, and in the subsequent heating step The precursor is imidized to form a polyimide.

[0077] In addition to the solvent and binder, the negative electrode active material layer 102 also contains a material for improving the characteristics of the electron conduction path. For this purpose, a conductive additive may be added. Examples of the conductive additive include acetylene black particles, Examples include carbon particles such as carbon nanofibers.

[0078] The above-mentioned compounds may be mixed using, for example, a kneader. For example, a planetary mixer can be used. The binder, the mixture, and the solvent are mixed together and mixed. A slurry (mixture) can be prepared by stirring using a kneader.

[0079] Next, the slurry (mixture) prepared by the above method is applied by a blade method or the like. Then, the negative electrode assembly on which the negative electrode active material layer 102 has been formed is The dielectric 101 is subjected to evaporation treatment in a dry atmosphere and / or a reduced pressure environment. The water or organic solvent contained in the negative electrode active material layer 102 is evaporated by the evaporation process. The treatment may be carried out, for example, at room temperature or 50°C in a dry atmosphere and / or under reduced pressure. This can be done by holding the mixture in a low temperature for about an hour. If the solvent can be removed, the evaporation treatment is not necessarily required.

[0080] Next, the negative electrode current collector 101 on which the negative electrode active material layer 102 has been formed is heated. 00°C or higher and 500°C or lower, preferably 300°C or higher and 400°C or lower, and this temperature is maintained for 3 hours or more. The reaction is carried out for 7 hours or less, preferably for about 5 hours.

[0081] By the above-described manufacturing process, a negative electrode having a negative electrode active material layer 102 on a negative electrode current collector 101 is obtained. 100 can be manufactured.

[0082] Note that the method for producing the negative electrode active material according to one embodiment of the present invention is not limited to the above method. In the documents, the steps of the manufacturing method are described as mixing of materials, separation of some materials, chemical The steps are classified into reaction processes and are shown as independent steps. In some cases, it may be difficult to classify the processes shown in the above manufacturing methods. There are cases where multiple steps are involved in one step, or where a single step spans multiple steps. Therefore, in the method for producing the negative electrode active material according to one embodiment of the present invention, The steps are not limited to the above steps and may be changed as appropriate. Specifically, depending on the situation, the order of each step may be changed, or steps may be added or deleted. It may be possible to do things like:

[0083] Note that this embodiment mode may be combined as appropriate with other embodiment modes and / or examples shown in this specification. It can be adjusted.

[0084] (Embodiment 2) In this embodiment, the negative electrode active material described in the previous embodiment is used in a secondary battery. Specifically, the positive electrode, the negative electrode, and the electrolyte are enclosed in an outer casing. This will be explained using a secondary battery enclosed in a protective film as an example.

[0085] <Positive electrode> The positive electrode includes a positive electrode active material layer and a positive electrode current collector.

[0086] <<Cathode active material>> The positive electrode active material layer contains at least a positive electrode active material. In addition, other substances such as a coating on the surface of the active material, a conductive additive, or a binder may be included.

[0087] The positive electrode active material may have, for example, an olivine type crystal structure, a layered rock salt type crystal structure, or Oxides and composite oxides having a spinel-type crystal structure can be used.

[0088] Examples of composite oxides having an olivine-type crystal structure include those represented by the general formula LiMPO4(M is a complex metal represented by one or more of Fe(II), Mn(II), Co(II), and Ni(II). A typical example of the general formula LiMPO4 is LiFePO4 , LiNiPO4, LiCoPO4, LiMnPO4, LiFe a Ni b PO4, LiF e a Co b PO4, LiFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4(a+b is less than 1, 0 <a<1、0<b<1)、LiFe c Ni d Co e PO4 , LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO4(c+d+e is less than 1 , 0 <c<1、0<d<1、0<e<1)、LiFe f Nig Co h Mn i PO4(f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc. Lithium compounds can be used as materials.

[0089] In particular, LiFePO4 satisfies well the requirements for a cathode active material, such as safety, stability, high capacity density, high potential, and the presence of lithium ions that can be extracted during initial oxidation (charging). Therefore, it is preferable.

[0090] Examples of the composite oxide having a layered rock salt type crystal structure include lithium cobalt oxide (L iCoO2), LiNiO2, LiMnO2, and Li2MnO3. Also, for example, LiNi 0.8 Co 0.2 O2, etc. of the NiCo system (general formula: LiNi x Co 1-x O 2(0 < x < 1)), LiNi 0.5 Mn 0.5 O2, etc. of the NiMn system (general formula: LiN i x Mn 1-x O2(0 < x < 1)), LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, etc. of the N iMnCo system (also referred to as NMC. General formula: LiNi x Mn y Co 1-x-y O2(x > 0, y > 0, x + y < 1)) are also included. Further, for example, Li(Ni 0.8 Co 0. 15 Al 0.05 )O2, Li2MnO3 - LiMO2 (M = Co, Ni, Mn), etc. are also included.

[0091] Examples of composite oxides having a spinel-type crystal structure include LiMn2O4, Li1 +x Mn 2ーx O4(0 <x<2)、LiMn 2-x Al x O4(0 <x<2)、LiM n 1.5 Ni 0.5 Examples include O4.

[0092] LiMn2O4, which has a spinel-type crystal structure containing manganese, and a small amount of nickel oxide Lithium (LiNiO2 and LiNi 1-x M x O2(M=Co, Al, etc., 0 <x<1)) Mixing with ammonium nitrate is preferred because it has the advantages of suppressing the elution of manganese and the decomposition of the electrolyte. It's nice.

[0093] In addition, the positive electrode active material is a compound of the general formula Li 2-j MSiO4 (M is Fe(II), Mn( Use composite materials such as one or more of Co(II), Co(II), Ni(II), 0≦j≦2) The general formula is Li 2-j A typical example of MSiO4 is Li 2-j FeSiO4, L i 2-j NiSiO4, Li 2-j CoSiO4, Li 2-j MnSiO4, Li 2-j Fe k Ni l SiO4, Li 2-j Fe k Co l SiO4, Li 2-j Fe k Mn l Si O4, Li 2-j Ni k Co l SiO4, Li 2-j Ni k Mn l SiO4 (k+l is 1 Below, 0 <k<1、0<l<1)、Li 2-j Fe m Ni n Co q SiO4, Li 2-j Fe m Ni n Mn q SiO4, Li 2-j Ni m Co n Mn q SiO4 (m+n+q is 1 Below, 0 <m<1、0<n<1、0<q<1)、Li 2-j Fe r Ni s Co t Mn u S iO4(r+s+t+u is 1 or less, 0 <r<1、0<s<1、0<t<1、0<u<1) Lithium compounds such as the above can be used as materials.

[0094] In addition, as the positive electrode active material, x M2(XO4)3(A=Li, Na, Mg, M=Fe, Mn, Ti, V, Nb, Al, X = S, P, Mo, W, As, Si) Nasicon-type compounds can be used. Nasicon-type compounds include Fe2(MnO4 )3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. Also, as a positive electrode active material, The general formula is Li2MPO4F, Li2MP2O7, Li5MO4 (M=Fe, Mn) compounds represented by the formula (I), perovskite-type fluorides such as NaFeF3 and FeF3, TiS2, M Metal chalcogenides (sulfides, selenides, tellurides) such as oS2, LiMVO4, etc. Oxides with an inverse spinel crystal structure, vanadium oxides (V2O5, V6O 13 , Materials such as LiV3O8, manganese oxides, and organic sulfur compounds can be used.

[0095] As the conductive additive, a carbon material, a metal material, a conductive ceramic material, or the like may be used. In addition, a fibrous material may be used as the conductive additive. The content of the conductive additive is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less. It is more preferable that the content is t% or less.

[0096] When a carbon material is used as the conductive additive, for example, natural graphite, mesocarbon microbeads, The carbon fiber may be selected from artificial graphite such as graphite, carbon fiber, etc. , mesophase pitch-based carbon fiber, isotropic pitch-based carbon fiber, etc. Carbon fibers such as carbon nanofibers and carbon nanotubes can also be used. Other carbon materials include, for example, carbon black (acetylene). black, graphite particles, graphene, fullerene, etc. do.

[0097] When metal fibers are used as the conductive additive, for example, copper, nickel, aluminum, It can be selected from metal powders such as silver and gold.

[0098] The conductive additive described above can form an electrical conductive network in the active material layer. This allows the active material layer to maintain an electrical conduction path between the active materials. By adding an electrical auxiliary agent, it is possible to realize an active material layer with high electrical conductivity. .

[0099] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isopropyl Ethylene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene- It is preferable to use a rubber material such as a propylene-diene copolymer. For this purpose, fluororubber can be used.

[0100] As the binder, it is preferable to use, for example, a water-soluble polymer. As the molecule, for example, polysaccharides can be used. cellulose (CMC), methylcellulose, ethylcellulose, hydroxypropyl Cellulose, diacetyl cellulose, regenerated cellulose and other cellulose derivatives, as well as starch In addition, these water-soluble polymers can be used in combination with the above-mentioned rubber materials. It is more preferable to use

[0101] Alternatively, the binder may be polystyrene, polymethyl acrylate, or polymethacrylic acid. Methyl (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), poly polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride , polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, poly Polyethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylic Polyaniline (PAN), Ethylene Propylene Diene Polymer, Polyvinyl Acetate, Nitrosene It is preferable to use a material such as cellulose.

[0102] Furthermore, the binder may be a combination of two or more of the above.

[0103] For example, a material having a particularly excellent viscosity adjusting effect may be used in combination with other materials. For example, rubber materials have excellent adhesive strength and elasticity, but it is difficult to adjust the viscosity when mixed with a solvent. In such cases, for example, mixing with a material that has a particularly excellent viscosity adjusting effect can be As a material having a particularly excellent viscosity adjusting effect, for example, a water-soluble polymer is used. In addition, examples of water-soluble polymers that are particularly effective in adjusting viscosity include the above-mentioned polysaccharides, for example, Carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydro cellulose such as hydroxypropyl cellulose, diacetyl cellulose, and regenerated cellulose; Derivatives and starch can be used.

[0104] The cellulose derivatives such as carboxymethyl cellulose are, for example, The solubility increases when cellulose is converted into salts such as sodium salts or ammonium salts. The increased solubility of the solubility of the electrode makes it easier to achieve the desired viscosity. It is also possible to improve the dispersibility of the active material and other components when preparing the battery. In the present invention, the cellulose and cellulose derivatives used as binders for the electrodes include: The salts thereof are also included.

[0105] Water-soluble polymers stabilize viscosity by dissolving in water, and also work well with active materials and binders. Other materials to be combined, such as styrene butadiene rubber, are stable in aqueous solution. In addition, since it has functional groups, it is easily and stably adsorbed onto the surface of the active material. It is expected that cellulose derivatives such as carboxymethyl cellulose can be Many materials have functional groups such as hydroxyl groups and carboxyl groups. It is expected that the polymers will interact with each other and widely cover the surface of the active material.

[0106] When the binder that covers or contacts the surface of the active material forms a film, it is called a passive film. It is expected that the passive film will also act as a barrier to prevent the decomposition of the electrolyte. A film with no electrical conductivity or extremely low electrical conductivity, for example, on the surface of an active material When a passive film is formed, it is possible to suppress the decomposition of the electrolyte at the battery reaction potential. In addition, the passive film suppresses electrical conductivity and does not allow lithium ions to be conducted. It is even more desirable to

[0107] <<Positive electrode current collector>> The positive electrode current collector may be made of metals such as stainless steel, gold, platinum, aluminum, titanium, etc. Highly conductive materials such as these alloys can be used. It is preferable that silicon, titanium, neodymium, scavenger, etc. are not eluted at the potential of the positive electrode. Aluminum alloys containing elements such as indium and molybdenum that improve heat resistance are used. It can also be formed from a metal element that reacts with silicon to form silicide. Metal elements that react with silicon to form silicide include zirconium, titanium, and Tantalum, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten , cobalt, nickel, etc. Current collectors are available in foil, plate (sheet), mesh, and punched shapes. The current collector may be in the form of a metal, an expanded metal, or the like. It is recommended to use a thickness of 5 μm or more and 30 μm or less.

[0108] <Electrolyte> The electrolytic solution contains a solvent and an electrolyte. The solvent for the electrolytic solution is preferably an aprotic organic solvent. Preferably, for example, ethylene carbonate (EC), propylene carbonate (PC), Ethylene carbonate, chloroethylene carbonate, vinylene carbonate, gamma-butyro Lactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfone oxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran One of tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in combinations and ratios of:

[0109] In addition, a flame-retardant and non-volatile ionic liquid (room-temperature molten salt) is used as the solvent for the electrolyte. By using one or more, the internal temperature of the secondary battery can be prevented from rising due to an internal short circuit or overcharging. Even if the battery is heated, it can prevent explosion and fire of the secondary battery. The electrolyte solution is made of tetravalent cations and anions. ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as imidazolium cations and pyridinium cations The following aromatic cations are also used as anions in electrolytes: monovalent amide-based Anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkanes perfluoroalkyl borate anion, tetrafluoroborate anion, perfluoroalkyl bo ... phosphate anion, hexafluorophosphate anion, or perfluoroalkyl phosphate hydrate anions, etc.

[0110] The electrolyte to be dissolved in the solvent is, for example, LiPF6, LiClO4, L iAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO 4. Li2B 10 Cl 10 , Li2B 12 Cl 12 , LiCF3SO3, LiC4F9S O3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(FSO2)2 , LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO2), LiN(C 2F5SO2)2 or any combination of two or more of these lithium salts. It can be used in any number and ratio.

[0111] The electrolyte used in secondary batteries is free from granular dust and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as " It is preferable to use a highly purified electrolyte solution with a low content of impurities. Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less, more preferably 1% or less. It is preferably 0.01% or less.

[0112] In addition, the electrolyte contains vinylene carbonate, propane sultone (PS), tert-butyl Benzene (TBB), Fluoroethylene carbonate (FEC), Lithium bis(oxa) Lithium borate (LiBOB), as well as dinitriles such as succinonitrile and adiponitrile The concentration of the additives may be, for example, The content should be between 0.1 wt% and 5 wt%.

[0113] Alternatively, a polymer gel electrolyte may be used in which a polymer is swollen with an electrolytic solution.

[0114] The use of polymer gel electrolyte increases safety against leakage etc. The pond can be made thinner and lighter.

[0115] Gelled polymers include silicone gel, acrylic gel, and acrylonitrile gel. , polyethylene oxide gel, polypropylene oxide gel, fluorine-based polymer A gel or the like can be used.

[0116] Examples of polymers include polyalkylene oxides such as polyethylene oxide (PEO). Polymers with side structures, PVDF, polyacrylonitrile, etc., and their For example, a copolymer containing PVDF and hexafluoropropylene ( PVDF-HFP, a copolymer of PVDF and HFP, can be used. The polymer may have a porous shape.

[0117] In addition, instead of the electrolytic solution, a solid electrolyte containing an inorganic material such as a sulfide or oxide, It is possible to use a solid electrolyte containing a polymer material such as PEO (polyethylene oxide). When a solid electrolyte is used, there is no need to install a separator or spacer. Since the entire battery can be solidified, there is no risk of leakage, dramatically improving safety.

[0118] <separator> The secondary battery preferably has a separator. Examples of the separator include: Paper, nonwoven fabric, glass fiber, ceramics, or nylon (polyamide), vinylon (polyamide) vinyl alcohol fiber), polyester, acrylic, polyolefin, polyurethane The separator can be made of synthetic fibers or the like. It is preferable to process the electrode into a shape and place it so as to wrap either the positive electrode or the negative electrode.

[0119] The separator may have a multi-layer structure. For example, the separator may be made of a material such as polypropylene or polyethylene. The material film is made of ceramic material, fluorine material, polyamide material, or any of these. The ceramic material can be coated with a mixture of oxides, etc. Aluminum particles, silicon oxide particles, etc. can be used. For example, PVDF, polytetrafluoroethylene, etc. can be used. Polyamide Materials used include nylon, aramid (meta-aramid, para-aramid), etc. You can be there.

[0120] Coating with ceramic materials improves oxidation resistance, making it possible to use separators during high-voltage charging and discharging. This suppresses the deterioration of the battery and improves the reliability of the secondary battery. Coating the separator and electrodes makes them adhere more easily, improving output characteristics. Coating polyamide materials, especially aramid, improves heat resistance, making them suitable for secondary batteries. Safety can be improved.

[0121] For example, a mixture of aluminum oxide and aramid is coated on both sides of a polypropylene film. Alternatively, aluminum oxide may be applied to the surface of the polypropylene film that comes into contact with the positive electrode. The surface that comes into contact with the negative electrode may be coated with a mixed material of rubber and aramid, and a fluorine-based material may be coated on the surface that comes into contact with the negative electrode. .

[0122] By using a multilayer separator, the safety of the secondary battery can be maintained even if the overall thickness of the separator is thin. Since the capacity per unit volume of the secondary battery can be increased,

[0123] <Outer package> As the outer package of the secondary battery, for example, a metal material such as aluminum or a resin material can be used. Also, a film-shaped outer package can be used. As the film, for example, a film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, polyamide is provided with a metal thin film excellent in flexibility such as aluminum, stainless steel, copper, nickel, etc. on the film made of the above materials, and further, an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided on the metal thin film as the outer surface of the outer package. A three-layer structure film can be used.

[0124] <Charging and discharging method> The charging and discharging of the secondary battery can be performed, for example, as follows.

[0125] <<CC charging>> First, CC charging will be described as one of the charging methods. CC charging is a charging method in which a constant current is passed through the secondary battery throughout the charging period and the charging is stopped when a predetermined voltage is reached. Assume that the secondary battery has an equivalent circuit of internal resistance R and secondary battery capacity C as shown in Fig. 5(A). In this case, the secondary battery voltage V B is the sum of the voltage V R applied to the internal resistance R and the voltage V applied to the secondary battery capacity C B That is, V R = V + V C In other words, V B = V R + V C is satisfied.

[0126] While CC charging is being performed, as shown in Fig. 5(A), the switch is turned on and a constant current I flows through the secondary battery. During this period, since the current I is constant, according to Ohm's law of V R = R×I, the voltage V applied to the internal resistance R R is also constant. On the other hand, for the secondary battery capacity C, voltage V C increases with the passage of time. Therefore, the secondary battery voltage V B increases with the passage of time .

[0127] And when the secondary battery voltage V B reaches a predetermined voltage, for example, 4.3V, charging is stopped . When CC charging is stopped, as shown in Fig. 5(B), the switch turns off and the current I = 0. Therefore, the voltage V R across the internal resistance R becomes 0V, and the secondary battery voltage V B is V B = V C . Therefore, in the charging stopped state, compared with just before the end of CC charging, the voltage drop across the internal resistance R disappears, so the secondary battery voltage V B decreases.

[0128] Examples of the time changes of the secondary battery voltage V B and the charging current during CC charging and in the CC charging stopped state are shown in Fig. 5(C). The secondary battery voltage V which was increasing during CC charging B is shown to decrease slightly after CC charging is stopped.

[0129] <<CCCV Charging>> Next, CCCV charging, which is a charging method different from the above, will be described. CCCV charging is first charging to a predetermined voltage by CC charging, and then charging by CV (constant voltage) charging until the current flowing becomes small, specifically, until it reaches the termination current value.

[0130] While CC charging is being performed, as shown in Fig. 6(A), the switch of the constant current power supply is on. The constant voltage power supply is switched off, and a constant current I flows through the secondary battery. During this time, the current I Since is constant, V R According to Ohm's law, the voltage V applied to the internal resistance R is R too On the other hand, the voltage V applied to the secondary battery capacity C is constant. C increases over time. Therefore, the secondary battery voltage V B is V B =V R +V C As a result, over time Rise.

[0131] and the secondary battery voltage V B When the voltage reaches a certain value, for example 4.3V, the CC charge is stopped. Switch to CV charging. During CV charging, the constant voltage voltage is The power supply switch is turned on, the constant current power supply switch is turned off, and the secondary battery voltage V B is constant On the other hand, the voltage V applied to the secondary battery capacity C C V increases over time. B =V R +V C Therefore, the voltage V across the internal resistance R R becomes smaller over time. Voltage V across internal resistance R R As becomes smaller, V R By Ohm's law, = R × I, The current I flowing through the secondary battery also becomes smaller.

[0132] When the current I flowing through the secondary battery reaches a predetermined value, for example, a current equivalent to 0.01C, When CCCV charging is stopped, all switches are turned off as shown in Figure 6(C). The switch is turned off and the current I becomes 0. Therefore, the voltage V applied to the internal resistance R R is 0V Become VB =V C becomes. However, due to the voltage V across the internal resistance R during CV charging R being sufficiently small, even if the voltage drop across the internal resistance R disappears, the secondary battery voltage V B hardly drops.

[0133] Examples of the time variations of the secondary battery voltage V during CCCV charging and in the state where CCCV charging is stopped are shown in Fig. 6(D). Even when CCCV charging is stopped, the state where the secondary battery B voltage V hardly drops is shown. battery voltage V B hardly drops is shown.

[0134] <<CC Discharge>> Next, CC discharge, which is one of the discharge methods, will be described. CC discharge is a discharge method in which a constant current flows from the secondary battery throughout the discharge period, and the discharge is stopped when the secondary battery voltage V reaches a predetermined voltage, for example, 2.5V. B becomes. is reached.

[0135] Examples of the time variations of the secondary battery voltage V, the discharge current, during CC discharge are shown in Fig. 7 B to show. As the discharge progresses, the state where the secondary battery voltage V B drops is shown.

[0136] Next, the discharge rate and the charge rate will be described. The discharge rate is the relative ratio of the current during discharge to the battery capacity, and is expressed in units of C. For a battery with a rated capacity of X (Ah), the current corresponding to 1C is X (A). When discharging with a current of 2X (A), it is said that discharging is performed at 2 C, and when discharging with a current of X / 5 (A), it is said that discharging is performed at 0.2C as such. Also, the charge rate is the same way. When charging with a current of 2X (A), it is at 2C when charging. If it is charged at a current of X / 5(A), it is said to be charged at 0.2C. cormorant.

[0137] Note that this embodiment mode may be combined as appropriate with other embodiment modes and / or examples shown in this specification. It can be adjusted.

[0138] (Embodiment 3) In this embodiment, the shape of the secondary battery having the negative electrode 100 described in the previous embodiment is The material used in the secondary battery described in this embodiment is the same as that in the previous embodiment. The description can be taken into consideration.

[0139] [Coin-type secondary battery] First, an example of a coin-type secondary battery will be described. 8(B) is a cross-sectional view of the secondary battery shown in FIG.

[0140] The coin-type secondary battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal. The can 302 is insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 30 provided in contact with the positive electrode current collector 305. The negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode current collector 308 which is set in contact with the negative electrode current collector 308. The negative electrode active material layer 309 is formed by the bonding.

[0141] The positive electrode 304 and the negative electrode 307 used in the coin-type secondary battery 300 are each effective. The active material layer may be formed on only one side.

[0142] The positive electrode can 301 and the negative electrode can 302 are made of nickel and aluminum, which are corrosion-resistant to the electrolyte. Metals such as aluminum and titanium, or alloys of these and other metals (e.g., stainless steel) In addition, nickel or aluminum can be used to prevent corrosion by the electrolyte. The positive electrode can 301 is preferably coated with a positive electrode 304, and the negative electrode can 302 is preferably coated with a negative electrode 305. 07 and electrically connect to each other.

[0143] The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte, and the resulting structure is shown in FIG. ) the positive electrode can 301 is placed downward, and the positive electrode 304, separator 310, negative electrode 307, The positive electrode can 301 and the negative electrode can 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are secured together with a gasket 303 interposed therebetween. Then, the laminate is pressed to manufacture a coin-type secondary battery 300.

[0144] By using the negative electrode active material described in the previous embodiment for the negative electrode 307, it is possible to achieve high capacity and cycle life. The coin-type secondary battery 300 can have excellent battery characteristics.

[0145] Here, the flow of current during charging of the secondary battery will be explained using FIG. 8(C). When a secondary battery is considered as a closed circuit, the movement of lithium ions and the flow of current are in the same direction. In secondary batteries that use lithium, the anode and cathode are connected by charging and discharging. The cathode (electrode) is switched, and the oxidation reaction and reduction reaction are switched. The electrode with a higher reaction potential is called the positive electrode, and the electrode with a lower reaction potential is called the negative electrode. In this case, even during charging, discharging, or when a reverse pulse current is applied, Even when an electric current flows through the positive electrode, it is called the "positive electrode" or "+ electrode (plus electrode)" and the negative electrode is called the "negative electrode" or "-electrode (minus electrode)". When the terms anode (positive electrode) and cathode (negative electrode) are used, the difference between charging and discharging is Therefore, the anode and cathode are often used interchangeably. The term "anode" (negative electrode) is not used in this specification. When using the terms "positive electrode" or "cathode," specify whether it is charging or discharging, and It will also be noted whether it corresponds to a positive pole (positive electrode) or a negative pole (negative electrode).

[0146] A charger is connected to the two terminals shown in FIG. 8(C), and the secondary battery 300 is charged. As the charging of the secondary battery 300 progresses, the potential difference between the electrodes increases.

[0147] [Cylindrical secondary battery] Next, an example of a cylindrical secondary battery will be described with reference to FIG. 9. Cylindrical secondary battery 600 As shown in FIGS. 9(A) and 9(B), the battery has a positive electrode cap (battery lid) 601 on the top surface and a side surface The positive electrode cap and the battery can (external can) 602 are disposed on the bottom surface. The container 602 is insulated from the container 602 by a gasket (insulating packing) 610.

[0148] Fig. 9(B) is a schematic diagram showing the cross section of a cylindrical secondary battery. Inside the can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are placed with a separator 605 sandwiched between them. The battery element is wound around a center pin (not shown). The battery can 602 is closed at one end and open at the other end. The material is nickel, aluminum, titanium, or other metals that are corrosion-resistant to the electrolyte, or Alloys of these and other metals (e.g., stainless steel) can be used. In addition, to prevent corrosion by the electrolyte, the battery can 602 is coated with nickel, aluminum, etc. It is preferable that the positive electrode, the negative electrode, and the separator are wound inside the battery can 602. The battery element is sandwiched between a pair of opposing insulating plates 608 and 609. A non-aqueous electrolyte (not shown) is poured into the battery can 602 in which the battery element is provided. The non-aqueous electrolyte may be the same as that used in coin-type secondary batteries.

[0149] The positive and negative electrodes used in cylindrical storage batteries are wound, so active material is formed on both sides of the current collector. A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604, and a negative A negative electrode terminal (negative electrode current collecting lead) 607 is connected to the positive electrode 603. The positive electrode terminal 607 can be made of a metal material such as aluminum. 603 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is a PTC (Positive Temperature Coefficient) element. The positive electrode cap 601 is electrically connected to the positive electrode cap 601 via a positive electrode coefficient 611. The safety valve mechanism 612 releases the positive electrode cap 601 when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 cuts off the electrical connection between the positive electrode 604 and the positive electrode 604. It is a thermal resistor whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current. It prevents abnormal heat generation. The PTC element is made of barium titanate (BaTiO3) Semiconductor ceramics and the like can be used.

[0150] 9(C), a plurality of secondary batteries 600 are mounted on conductive plates 613 and 614. The secondary batteries 600 may be sandwiched between the secondary batteries 600 to form a module 615. They may be connected in series, or may be connected in parallel and then connected in series. By configuring a module 615 having a plurality of secondary batteries 600, It can extract a large amount of power.

[0151] FIG. 9(D) is a top view of the module 615. For clarity of illustration, the conductive plate 613 is As shown in FIG. 9(D), the module 615 is a module that connects a plurality of secondary batteries 600 to each other. The conductive plate 616 may be provided on the conductive wire 616. Furthermore, a temperature control device 617 may be provided between the plurality of secondary batteries 600. When the secondary battery 600 is overheated, the temperature control device 617 cools the secondary battery 600. If the temperature controller 617 is too cold, it can be heated. The performance of the module 615 is less affected by the outside temperature. The body is preferably insulating and non-flammable.

[0152] By using the negative electrode active material described in the above embodiment for the negative electrode 606, high capacity and cycle The cylindrical secondary battery 600 can be made to have excellent battery characteristics.

[0153] [Solid battery] Next, an example of a solid-state battery will be described. The negative electrode according to one embodiment of the present invention is applied to a solid-state battery. Fig. 10 is a diagram showing the positive electrode, solid electrolyte, and negative electrode of a solid-state battery. The secondary battery 700 shown in FIG. 10 has a positive electrode 710, a solid electrolyte layer 720, and a negative electrode 730. do.

[0154] The positive electrode 710 includes a positive electrode current collector 713 and a positive electrode active material layer 714. The positive electrode active material layer 714 has a positive electrode active material 711 and a solid electrolyte 721. It may contain an electrical activator and a binder.

[0155] The solid electrolyte layer 720 includes a solid electrolyte 721. The solid electrolyte layer 720 includes a positive electrode 710. and the negative electrode 730, and does not have either the positive electrode active material 711 or the negative electrode active material 731. This is a challenging area.

[0156] The negative electrode 730 includes a negative electrode current collector 733 and a negative electrode active material layer 734. 4 has a negative electrode active material 731 and a solid electrolyte 721.

[0157] The negative electrode of one embodiment of the present invention can be used as the negative electrode 730 of the secondary battery 700 shown in FIG. Specifically, the secondary battery 700 can use LTPO, LATP as the solid electrolyte 721. Lithium conductive ceramics such as 731 are used, and silicon is used as the negative electrode active material. The configuration can be as follows.

[0158] Note that this embodiment mode may be combined as appropriate with other embodiment modes and / or examples shown in this specification. It can be adjusted.

[0159] (Fourth embodiment) In this embodiment, an example in which a secondary battery according to one embodiment of the present invention is mounted in an electronic device will be described. Reveal.

[0160] <Tablet-type device> First, Fig. 11(A) and Fig. 11(B) show an example of a foldable tablet terminal. The tablet terminal 9600 shown in FIGS. 11(A) and 11(B) includes a housing 96 30a, a housing 9630b, a movable part 9640 connecting the housings 9630a and 9630b, Display unit 9631, switches 9625 to 9627, fastener 9629, operation switch The display portion 9631 is made of a flexible panel, The tablet terminal can have a wider display area. 11(A) shows the tablet terminal 9600 in an open state, and FIG. 11(B) shows the tablet terminal 9600 in a closed state. This shows the state.

[0161] The tablet terminal 9600 also includes a housing 9630a and a housing 9630b. The power storage unit 9635 is connected to the housing 9630a through a movable part 9640. It is provided across the body 9630b.

[0162] The entire or part of the display area 9631 can be used as a touch panel area. By touching the displayed operation keys 9638, data can be input. For example, A keyboard button is displayed on the display unit 9631 on the housing 9630a side, and The display portion 9631 may be used to display characters, information, images, and the like.

[0163] In addition, a keyboard is displayed on the display unit 9631 on the housing 9630b side, and The display unit 9631 on the side may be used to display characters, information, images, etc. 631 to display the keyboard display switch button on the touch panel, and By touching the keyboard with a finger or a stylus, keyboard buttons are displayed on the display unit 9631. It is also possible to configure it so that this is possible.

[0164] In addition, the switches 9625, 9626, and 9627 are equipped with tablet terminals. Not only is it an interface for operating the 9600, but it also switches between various functions. For example, the switches 9625 to 9626 may be an interface that can At least one of the devices 627 is a switch for switching on and off the power of the tablet terminal 9600. For example, the switches 9625 to 9627 may function as At least one function to switch the display orientation, such as portrait or landscape, or monochrome display The switches 9625 to 9628 may have a function of switching between color displays. At least one of the switches 9627 may have a function of adjusting the brightness of the display portion 9631 . The brightness of the display portion 9631 is detected by a light sensor built into the tablet terminal 9600. It can be configured to be optimized according to the amount of external light emitted during use. The mobile terminal not only has optical sensors, but also sensors that detect tilt, such as gyros and acceleration sensors. Any other detection device may be incorporated.

[0165] FIG. 11(B) shows the tablet terminal 9600 in a folded state. The portable terminal 9600 includes a housing 9630, a solar cell 9633, and a DC-DC converter 9636. In addition, a charge / discharge control circuit 9634 including a power storage unit 9635 is provided. Such a secondary battery is used.

[0166] As mentioned above, the tablet terminal 9600 can be folded in half, so when not in use, the case The housing 9630a and the housing 9630b can be folded so that they overlap each other. By doing so, the display portion 9631 can be protected, and therefore the durability of the tablet terminal 9600 can be improved. Furthermore, the power storage unit 9635 using the secondary battery of one embodiment of the present invention can have a high capacity. It has good cycle characteristics and can be used for a long period of time. A terminal 9600 can be provided.

[0167] In addition, the tablet terminal 9600 shown in FIG. 11(A) and FIG. 11(B) It has the function to display various information (still images, videos, text images, etc.), calendar, date Or a function to display the time etc. on the display, or to touch input or edit the information displayed on the display Touch input function, function to control processing by various software (programs), etc.

[0168] The tablet terminal 9600 is equipped with a solar cell 9633 on its surface, which generates power. The solar cell 96 can supply the power to the panel, the display unit, the video signal processing unit, etc. 33 can be provided on one or both sides of the housing 9630, and can efficiently charge the power storage unit 9635. The power storage unit 9635 can be configured to use a lithium ion battery. The use of such a device has the advantage of enabling miniaturization.

[0169] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 11B are A block diagram is shown in FIG. 11(C) and will be explained. In FIG. 11(C), a solar cell 9633, a power storage unit 96 35, DC-DC converter 9636, converter 9637, switch SW1 to switch SW3, display unit 9631, power storage unit 9635, DC-DC converter 96 36, converter 9637, and switches SW1 to SW3 are shown in FIG. This corresponds to the charge / discharge control circuit 9634 .

[0170] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted into a voltage to charge the storage battery 9635. The converter 9636 increases or decreases the voltage. When power is used from the battery 9633, the switch SW1 is turned on, and the converter 963 7, the voltage is increased or decreased to the voltage required for the display unit 9631. When not displaying in 1, turn switch SW1 off and switch SW2 on. The power storage unit 9635 may be charged.

[0171] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. Storage by other power generation means such as piezoelectric elements and thermoelectric conversion elements (Peltier elements) For example, the power supply 9635 may be configured to transmit and receive power wirelessly (contactlessly). It is also possible to combine it with a contactless power transmission module that charges the battery, or other charging means. You may do so.

[0172] <Home appliances> Another example of electronic equipment is shown in FIG. 12. In FIG. 12, a display device 8000 is a display device according to the present invention. 8 is an example of a home appliance using a secondary battery 8004 according to one embodiment. 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, a speaker, and The secondary battery 8004 according to one embodiment of the present invention includes: The display device 8000 is provided inside a housing 8001. The display device 8000 is supplied with power from a commercial power source. It is also possible to use the power stored in the secondary battery 8004. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the present invention can be used. The display device 8000 can be used by using the secondary battery 8004 as an uninterruptible power supply. become.

[0173] The display unit 8002 is a display device having a light emitting element such as a liquid crystal display device or an organic EL element in each pixel. Optical devices, electrophoretic displays, DMD (Digital Micromirror Devices) ice), PDP (Plasma Display Panel), FED (Field A semiconductor display device such as a reflective LED (emission display) can be used.

[0174] In addition to TV broadcast reception, display devices are also used for personal computers and advertising displays. This includes all display devices for displaying information, such as:

[0175] In FIG. 12, a stationary lighting device 8100 includes a secondary battery 8 according to one embodiment of the present invention. 8103. Specifically, the lighting device 8100 includes a housing 8101, 12, the secondary battery 8103 is disposed in the housing 8. 101 and a light source 8102 are installed inside a ceiling 8104. 8, the secondary battery 8103 may be provided inside the housing 8101. The device 8100 can be supplied with power from a commercial power source or can be powered by a secondary battery 8103. The stored power can also be used. Therefore, in the event of a power outage, the power supply from the commercial power source can be reduced. Even when power is not available, the secondary battery 8103 according to one embodiment of the present invention can be used as an uninterruptible power supply. This allows the lighting device 8100 to be used.

[0176] In addition, FIG. 12 illustrates a lighting device 8100 of a fixed type provided on a ceiling 8104. However, in the secondary battery according to one embodiment of the present invention, the side wall 8105, the floor 8106, and the like are not included in the ceiling 8104. It can be used for a fixed lighting device provided in a window 8107 or a desk. It can also be used in upper lighting devices.

[0177] The light source 8102 can be an artificial light source that artificially obtains light using electricity. Specifically, this applies to incandescent lamps, discharge lamps such as fluorescent lamps, and light-emitting devices such as LEDs and organic EL elements. An example of the artificial light source is a light element.

[0178] In FIG. 12, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is 8 is an example of an electronic device using a secondary battery 8203 of one embodiment of the present invention. The indoor unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. In the example shown, the secondary battery 8203 is provided in the indoor unit 8200. The secondary battery 8203 may be provided in the outdoor unit 8204. Both the outdoor units 8204 may be provided with a secondary battery 8203. The battery can be supplied with power from a commercial power source or stored in a secondary battery 8203. In particular, both the indoor unit 8200 and the outdoor unit 8204 are equipped with secondary batteries 8 If 203 is installed, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8203 of one embodiment of the present invention as an uninterruptible power supply, Conditioner can be used.

[0179] In addition, Figure 12 shows a separate type air conditioner consisting of an indoor unit and an outdoor unit. However, it is an integrated air conditioner that has the functions of both an indoor unit and an outdoor unit in a single housing. The secondary battery according to one embodiment of the present invention can also be used for the conditioner.

[0180] In FIG. 12, an electric refrigerator-freezer 8300 includes a secondary battery 8304 according to one embodiment of the present invention. Specifically, an electric refrigerator-freezer 8300 includes a housing 8301, It has a refrigerator door 8302, a freezer door 8303, a secondary battery 8304, etc. A secondary battery 8304 is provided inside the housing 8301. The power can be supplied from a commercial power source or can be stored in a secondary battery 8304. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. Even in this case, by using the secondary battery 8304 of one embodiment of the present invention as an uninterruptible power supply, 8300 refrigerators and freezers will be available for use.

[0181] Among the above-mentioned electronic devices, high-frequency heating devices such as microwave ovens and electric rice cookers The sub-devices require high power for a short period of time, so the power that cannot be supplied by the commercial power supply is supplemented. By using a secondary battery according to one embodiment of the present invention as an auxiliary power source for supporting This can prevent the commercial power breaker from tripping when using the

[0182] In addition, during times when electronic devices are not in use, the total amount of power that can be supplied by commercial power suppliers is also During the time period when the ratio of the amount of electricity actually used (called the electricity usage rate) is low, By storing power in the secondary battery, it is possible to prevent power usage rates from increasing outside the above time periods. For example, in the case of the electric refrigerator-freezer 8300, when the temperature is low, the refrigerator compartment door 83 02, during the night when the freezer door 8303 is not opened or closed, power is supplied to the secondary battery 8304. Then, as the temperature rises, the refrigerator door 8302 and the freezer door 8303 open and close. During the daytime, when the vehicle is in operation, the secondary battery 8304 is used as an auxiliary power source, thereby reducing the power consumption during the daytime. The rate can be kept low.

[0183] According to one embodiment of the present invention, the cycle characteristics of a secondary battery can be improved, and the reliability can be improved. Furthermore, according to one aspect of the present invention, a high-capacity secondary battery can be obtained. This improves the characteristics of the secondary battery, thereby making the secondary battery itself smaller and lighter. Therefore, the secondary battery according to one embodiment of the present invention can be used in the electronic devices described in this embodiment. By incorporating the technology into the electronic device, it is possible to create an electronic device with a longer lifespan and lighter weight.

[0184] <Mobile object> Next, an example in which the secondary battery according to one embodiment of the present invention is mounted on a mobile object such as a vehicle will be described.

[0185] When secondary batteries are installed in a vehicle, hybrid vehicles (HEVs), electric vehicles (EVs), or will help realize next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs). Cut.

[0186] FIG. 13 illustrates an example of a mobile object using a secondary battery according to one embodiment of the present invention. The automobile 8400 shown in A) is an electric automobile that uses an electric motor as a power source for running. Or, it is a vehicle that uses an electric motor and an engine as a power source for driving. By using one embodiment of the present invention, the cruising range can be The car 8400 also has a secondary battery. The battery is mounted on the floor of the vehicle using the secondary battery module shown in Fig. 9(C) and Fig. 9(D). The secondary battery not only drives the electric motor 8406, Supplying power to light emitting devices such as headlights 8401 and room lights (not shown) can be done.

[0187] In addition, the secondary battery is used for the displays of the car 8400, such as the speedometer and tachometer. The secondary battery can supply power to the navigation system of the automobile 8400. The power supply can be used to power semiconductor devices such as gating systems.

[0188] The automobile 8500 shown in FIG. 13(B) has a plug-in secondary battery. It can be charged by receiving power from an external charging facility using a method such as contactless power supply. FIG. 13(B) shows a diagram of a charging device 8021 mounted on a ground and a charging system 8022 mounted on a vehicle 8500. The secondary battery 8024 is shown being charged via a cable 8022. For charging methods and connector specifications, please refer to the specifications of CHAdeMO (registered trademark) and Combo. The charging device 8021 may be a charging station installed in a commercial facility. For example, plug-in technology can be used to The secondary battery 8024 mounted on the automobile 8500 can be charged by the power supply of Charging is performed by converting AC power to DC power via a converter such as an AC / DC converter. It is possible to do so.

[0189] Although not shown, a power receiving device is mounted on a moving object, and power is transmitted contactlessly from a power transmitting device on the ground. In this case, the power transmission device is attached to the road or exterior wall. By incorporating this, charging can be done not only when the vehicle is stopped but also while the vehicle is moving. The power supply method may be used to transmit and receive power between mobile units. A solar cell may be provided on the exterior of the vehicle to charge the secondary battery while the vehicle is stopped or running. For contactless power supply, an electromagnetic induction method or a magnetic field resonance method can be used.

[0190] FIG. 13C shows an example of a two-wheeled vehicle using the secondary battery of one embodiment of the present invention. The scooter 8600 shown in FIG. 3(C) includes a secondary battery 8602, side mirrors 8601, and a directional indicator. The secondary battery 8602 supplies electricity to the direction indicator light 8603. can be done.

[0191] In addition, the scooter 8600 shown in FIG. 13(C) has a secondary battery 86 in the storage under the seat 8604. The secondary battery 8602 can be stored in the under-seat storage 8604, which is small. The secondary battery 8602 can be stored in the under-seat storage 8604. When charging, the secondary battery 8602 is brought indoors, charged, and then stored away before driving. Just pay it.

[0192] According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved, and the capacity of the secondary battery is increased. Therefore, the secondary battery itself can be made smaller and lighter. If the vehicle itself can be made smaller and lighter, it will contribute to reducing the weight of the vehicle, thereby improving the cruising range. In addition, the secondary battery installed in the mobile object can be used as a power supply source for other objects. In this case, for example, it is possible to avoid using commercial power sources during peak power demand periods. If we can avoid using commercial power sources during peak power demand periods, we can save energy and This can contribute to reducing carbon dioxide emissions. This allows secondary batteries to be used for a long period of time, reducing the amount of rare metals used, including cobalt. can be reduced.

[0193] Note that this embodiment mode may be combined as appropriate with other embodiment modes and / or examples shown in this specification. It can be adjusted. [Example]

[0194] In this example, a negative electrode active material according to one embodiment of the present invention was prepared and analyzed. The results will be explained.

[0195] <Sample production> The procedure for preparing the negative electrode active material that was analyzed will be described. Sample SP1 was prepared by adding silicon to LTPO (first mixture). In addition, sample SP2 was prepared by adding silicon to LATP (second mixture). Furthermore, sample SP3 was prepared by coating sample SP2 with RGO.

[0196] <<Sample SP1>> First, the fabrication procedure of sample SP1 will be described. As explained in step S01 of 1, lithium carbonate (Li2CO3), titanium oxide (T The raw materials are ammonium hydrogen phosphate (NH4H2PO4), and the test Each raw material was weighed so that the total amount was LiTi2(PO4)3.

[0197] Next, in step S02, the starting materials were mixed using a ball mill. The mixing conditions were as follows: wet mixing was performed using dehydrated acetone and 3 mm diameter zirconia balls. Mixing and crushing were carried out using a grinder at a rotation speed of 300 rpm for 2 hours.

[0198] Thereafter, the zirconia balls were separated from the mixture using a sieve with 1 mm openings. At this time, any contaminants adhering to the edges of the sieve, gaps in the mesh, zirconia balls, etc. In order to separate the adhering mixture, dehydrated acetone was injected to separate the adhering mixture.

[0199] Then, in order to remove the dehydrated acetone contained in the mixture obtained by separation, the mixture was heated at 60°C. The dried acetone was evaporated by placing it on a hot plate.

[0200] Next, in step S03, the mixture from which the dehydrated acetone was evaporated was placed in an alumina crucible. The mixture was heated in a muffle furnace under nitrogen atmosphere at 400°C for 10 hours. Furthermore, the process decomposes the starting material, ammonium hydrogen phosphate.

[0201] Next, in step S04, the fired product prepared in step S03 is crushed in a mortar. The crushed fired material was then crushed more finely using a ball mill. The crushing was carried out under the same conditions as in step S02, using dehydrated acetone as a wet method. The mixture was mixed using a zirconia ball at a rotation speed of 300 rpm for 2 hours.

[0202] Then, in the same manner as in step S02 above, the zirconia boron is sieved using a sieve with a mesh size of 1 mm. The crushed material is separated from the fuel, and the dehydrated acetone contained in the separated crushed material is removed. The dehydrated acetone was evaporated on a hot plate at 0°C.

[0203] Next, in step S05, the crushed material from which the dehydrated acetone has been evaporated is placed in an alumina crucible. The mixture was then sintered in a muffle furnace under nitrogen atmosphere at 900°C for 12 hours. .

[0204] After the main firing, the fired product was crushed in a mortar as in step S06. The crushed fired material was then passed through a sieve and finely crushed in a ball mill. The ball mill crushing was carried out using dehydrated acetone as a wet method and zirconia balls. The reaction was carried out at a rotation speed of 300 rpm for 6 hours.

[0205] Then, the zirconia balls and the crushed material were separated using a 20 μm sieve. In order to remove the dehydrated acetone contained in the crushed material, it was placed on a hot plate at 60°C and dehydrated. The acetone was evaporated.

[0206] In step S11, the LTPO produced in step S06 and the nanosilicon (Sig 1 g of each of 1 g of PEG-100 (manufactured by Aldrich) and 1 g of PEG-100 were prepared and mixed using a ball mill. Specifically, the mixing conditions were as follows: wet mixing was performed using dehydrated acetone, and zirconia balls were used. Mixing and crushing were carried out using a grinder at a rotation speed of 300 rpm for 2 hours.

[0207] Thereafter, in the same manner as in step S06, the zirconia balls are sieved using a 20 μm sieve. The crushed material is separated from the crushed material, and the mixture is heated at 60℃ to remove the dehydrated acetone contained in the separated mixture. The dried acetone was evaporated by placing it on a hot plate.

[0208] Next, in step S12, the mixture from which acetone has been removed is tableted using a tablet press. Specifically, the mixture was packed into a pellet die with a diameter of 15 mm and subjected to a pressure of 14.7 MPa. Pressure was applied for 5 minutes to produce a molded product.

[0209] Next, in step S13, the molded product is placed in an alumina crucible and heated in a muffle furnace. The heating was carried out under the conditions of a nitrogen atmosphere, 900°C, and 5 hours.

[0210] Finally, the fired product prepared above was crushed in a mortar and further crushed into finer particles using a ball mill. In the ball mill crushing, dehydrated acetone was used as a wet method, and the particles were crushed to 3 mm. The crushing was carried out for 2 hours at a rotation speed of 300 rpm using zirconia balls of φ. The mixture of nanosilicon and LTPO (sample SP1) was sieved through a 1 mm mesh sieve. was produced.

[0211] <<Sample SP2>> Next, a manufacturing procedure of sample SP2 will be described. As described in the preparation of LATP, lithium carbonate (Li2CO3), titanium oxide (T iO2), ammonium hydrogen phosphate (NH4H2PO4), aluminum oxide (Al2O 3) is used as the raw material, and the first sample to be prepared is LiTi 1.7 Al 0.3 (PO4)3 Each raw material was weighed so that

[0212] The following fabrication procedures were based on those of sample SP1. Sample SP2 was prepared using the same procedure as sample SP1.

[0213] <<Sample SP3>> Next, the procedure for producing sample SP3 will be described. As described above, sample SP3 Sample SP2, which is a mixture of nanosilicon and LATP (second mixture), was coated with RGO. This is a filmed sample.

[0214] First, as described in step S21 of the first embodiment, the second mixture (sample SP 2) was prepared in an amount of 0.75 g. It was also spray-dried using a spray dryer. 0.01526 g of GO manufactured by Nishina Materials Co., Ltd. was prepared. The mass of this GO was The mass of the sample SP2 to be prepared is set so that the proportion of GO contained in the sample SP2 is 2 wt%. do.

[0215] Next, in step S22, water is added to GO, and then the GO is mixed with water using a mixer. The addition of water and stirring were repeated 9 times. The conditions are shown in the table below. Also, as shown in the table below, the stirring conditions were the same for all of the 1st to 9th times. The mixture was stirred at 2000 rpm for 5 minutes.

[0216] [Table 1]

[0217] Next, in step S23, the stirred GO is mixed with the second mixture prepared in step S21. The mixture was added to the mixture and kneaded using a mixer at 2000 rpm for 5 minutes. It was decided.

[0218] In step S24, the kneaded mixture prepared in step S23 is placed in a ventilation drying oven. The mixture was then dried at 50°C for 12 hours to remove water.

[0219] Thereafter, in step S25, the mixture prepared in step S24 is pulverized in a mortar. The mixture was crushed and passed through a 300 μm sieve.

[0220] Next, in step S26, the mixture prepared in step S25 is mixed with ethanol, aspartame, and Corbic acid was reduced using lithium hydroxide hydrate (LiOH·H2O). First, add 0.0506 g of ascorbic acid and lithium hydroxide hexahydrate to 15 ml of ethanol. The mixture was added to the solution and heated at 60°C for 3 hours. Next, ascorbic acid and lithium hydroxide were washed away with ethanol, and then The mixture was washed with seton and then recovered, and after recovery, the mixture was crushed in a mortar.

[0221] Thereafter, in steps S27 and S28, the obtained mixture is poured into a glass tube. The sample was dried in a vacuum oven at 250°C for 10 hours. This allows for the removal of water and / or organic solvents while simultaneously thermally reducing the GO contained in the mixture. It is possible.

[0222] Then, in step S29, the mixture prepared in steps S27 and S28 is The mixture was crushed in a mortar and pestle, and then passed through a 20 μm mesh sieve to recover the mixture. The analysis was carried out as sample SP3.

[0223] <SEM observation results of negative electrode active material> Figure 14 shows the SEM (Scanning Electron Microscope) image of sample SP2. The results of SEM-EDX (Energy Dispersive X-ray Diffraction) observations were Figure 14(A) shows the results of elemental analysis by ray spectroscopy. 14(B) to (E) are SEM images of sample SP2, and each of them is a Kα1 ray. Silicon (Si), oxygen (O), phosphorus (P), and titanium (Ti) obtained by SEM-EDX From Fig. 14(A), it can be seen that the size of the particles is generally between 10 nm and 100 nm. It was found that the primary particles, silicon and LATP, aggregated together to form secondary particles. 14(B) to (E), sample SP2 is composed of silicon and LATP. It can be seen that the particles are dispersed almost uniformly.

[0224] <XRD analysis of negative electrode active material> For the negative electrode active materials sample SP1 and sample SP2 prepared above, CuK The powder was analyzed by X-ray diffraction (XRD) using α1 radiation. The XRD device used was a Bruker D8 ADVANCE. is an out-of-plane method, and the 2θ range is from 15° to 90° in 0.01 increments. Measured.

[0225] 15 and 16 show the powder XR for sample SP1 and sample SP2, respectively. The measurement results shown in Fig. 15 and Fig. 16 are plotted on the horizontal axis as 2θ(d The vertical axis is the intensity (arb units). For comparison, Figure 15 shows the results of Si, LiTi2(PO4)3, TiO2(rutile), and S The XRD pattern of iO2 (cristobalite) is also shown in Figure 16. In addition to Si, TiO2 (rutile), and SiO2 (cristobalite), Li instead of LiTi2(PO4)3 1.3 Al 0.3 Ti 1.7 (PO4)3 XR The D pattern is also shown. 1.3 Al 0.3 Ti 1.7 (PO4)3, TiO2(rutile), SiO2(cristobali The XRD patterns of each of the ICSD (Inorganic Crystal The XRD pattern was obtained from the Structure Database. , the step width of 2θ is 0.01°, and the wavelength λ1 is 1.540562×10 -10 m The wavelength λ2 was set not to be used.

[0226] In the XRD pattern of sample SP1 shown in Figure 15, 2θ = 28.2 ± 0.1° (28 .1° or more and 28.3° or less), 2θ=47.3±0.1° (46.2° or more and 47.4° or less) bottom), and a diffraction peak at 2θ = 56.0 ± 0.1° (55.9° to 56.1°). The positions where these diffraction peaks appear are the same as those of the diffraction peaks in the XRD pattern of Si. It can be seen that the positions where the peaks appear are almost identical. Similarly, the XRD pattern of SP2 showed a 2θ=28.2±0.1° (28.1° or more, 28° 0.3° or less), 2θ=47.3±0.1° (47.2° or more and 47.4° or less), and 2θ =56.0±0.1° (55.9° to 56.1°) This also roughly coincides with the position where the diffraction peaks appear in the XRD pattern of Si. You can see that.

[0227] In addition, in the XRD pattern of sample SP1 shown in Figure 15, 2θ = 20.9 ± 0.1° (20.8° or more and 21.0° or less), 2θ=24.5±0.1° (24.4° or more and 24. Diffraction peaks appear at positions (below 6°), and these positions correspond to LiTi2(PO4)3 The positions of the diffraction peaks in the XRD pattern of the sample almost coincide with those of the sample. The XRD pattern of SP1 shows 2θ=24.1±0.1° (between 24.0° and 24.2°). The XRD patterns of Si and LiTi2(PO4)3 could not be identified. In addition, in the XRD pattern of LiTi2(PO4)3, Diffraction peaks appear at 2θ=32.4±0.1° (32.3° to 32.5°) At positions such as 2θ=33.2±0.1° (32.1° or more and 33.3° or less), the sample In the XRD pattern of SP1, no diffraction peaks appear (or the diffraction peaks are weak). This indicates that sample SP1 has a low LTPO content and a high impurity content. is considered to be high.

[0228] On the other hand, in the XRD pattern of sample SP2 shown in Figure 16, 2θ = 20.9 ± 0.1° (20.8° or more and 21.0° or less), 2θ=24.5±0.1° (24.4° or more and 24. 2θ=32.4±0.1° (32.3° or more and 32.5° or less) ), 2θ=33.2±0.1° (33.1° or more and 33.3° or less), etc. In other words, the XRD pattern of sample SP2 shows Si and Li 1.3 Al 0.3 Ti 1.7 XRD pattern of (PO4)3 with few unidentifiable diffraction peaks Therefore, sample SP2 is considered to have a high LATP content and a low impurity content. .

[0229] 15 and 16, the XRD patterns of sample SP1 and sample SP2 are The sintered material is TiO2 (rutile) and SiO2 (cristobalite). Since there are few positions that can be identified as diffraction peaks in each XRD pattern, sample SP Samples 1 and SP2 did not decompose into TiO2 and SiO2, respectively. can be inferred.

[0230] In addition, the XRD patterns obtained above were analyzed using TOPAS ver.3 (Bruke Rietveld analysis was performed using crystal structure analysis software manufactured by r. The results are shown in Figure 1. In sample SP1, the crystallite size of nanosilicon was 61 nm, and that of LTPO was 1. The crystal size was calculated to be 30 nm. In addition, in FIG. 16, in sample SP2, The crystallite size of silicon was calculated to be 60 nm, and the crystallite size of LATP was calculated to be 68 nm. The results show that the crystal sizes of nanosilicon and LATP are almost the same. It is assumed that this is the case.

[0231] <Test cell fabrication and measurement> The negative electrode active materials (samples SP1 to SP3) prepared above were used to test CR20 32 types (diameter 20mm height 3.2mm) of coin-type (Li half cell) test cells was produced.

[0232] The negative electrode was made of one of Samples SP1 to SP3 (hereinafter, SP), acetylene black (AB), and polyimide (PI, more precisely, polyimide A slurry of SP:AB:PI = 80:5:15 (weight ratio) mixed with AB (precursor of AB) and PI The above was applied to a nickel-plated copper foil as a current collector.

[0233] Specifically, first, NMP (N-methyl-2-pyrrolidone) was used as a solvent, and the sample was Mix any one of samples SP1 to SP3 with acetylene black in a mixer. Next, the polyimide precursor and NMP were further added and mixed in a mixer to form a slurry. Then, the slurry was applied to a current collector using a blade method. The blade speed was set to 10 mm / sec. Finally, the polyimide precursor was imidized. To achieve this, the slurry applied to the current collector was heated at 400°C for 5 hours in a nitrogen atmosphere. The negative electrode was fabricated by carrying out the above steps.

[0234] In order to prepare negative electrodes with different loading amounts, the blade method in the above preparation example was used. The gap between the electrode and the current collector was set to two conditions: 50 μm and 100 μm. The loading amount of Puru SP1 on the negative electrode was 0.67 mg / cm under each condition. 2 , 1.3 1 mg / cm 2 In addition, the amount of support on the negative electrode using sample SP2 was 0.77mg / cm 2 , 1.37 mg / cm 2 Furthermore, sample SP3 The amount of carbon supported on the negative electrode used was 0.63 mg / cm under each condition. 2 , 1.18 mg / cm 2 This is what happened.

[0235] The counter electrode was made of lithium metal, and the separator was made of polypropylene.

[0236] The electrolyte used in the electrolytic solution is 1 mol / L lithium hexafluorophosphate (LiPF6). The electrolyte contains ethylene carbonate (EC) and diethyl carbonate (DEC). A mixture of C:DEC=3:7 (volume ratio) was used.

[0237] In this example, sample SP1 was used, and the loading amount was 0.67 mg / cm 2 The negative electrode is The test cell used is referred to as cell CS1[1], and sample SP1 was used, with a loading of 1. 31 mg / cm 2 The test cell using the negative electrode is referred to as cell CS1[2]. Sample SP2 was used, with a loading of 0.77 mg / cm 2 Test cell using a negative electrode is described as cell CS2 [1], and sample SP2 is used, with a loading of 1.37 mg / cm 2 The test cell using the negative electrode is referred to as cell CS2[2]. The loading was 0.63 mg / cm 2 The test cell with the negative electrode of cell CS3[1 ] and sample SP3 was used, with a loading of 1.18 mg / cm 2 Using a negative electrode that is The test cell is referred to as cell CS3[2]. ], those of cell CS2[1], cell CS2[2], cell CS3[1], cell CS3[2] The results of measuring the cycle characteristics of each battery will be explained below.

[0238] Figure 17 shows the cells CS1[1], CS1[2], CS2[1], and CS2[2]. ], cell CS3[1], cell CS3[2], and the cycle characteristics of cell CS4. The graph shows the number of cycles on the horizontal axis and the discharge capacity (mAh / g) on the vertical axis. Cell CS4 uses nanosilicon as the negative electrode with a loading of 0.83 mg / cm. 2 year This is a test cell formed on a current collector using the above method.

[0239] The measurement conditions for the test cell are as follows. The charge / discharge method is 0.1C for the first charge / discharge only. Constant current-constant voltage charge and constant current discharge are performed at a rate of 0.2C from the second time onwards. The constant current-constant voltage charge and constant current discharge were performed at 1.5V. The lower limit voltage was set to 0.01 V, and the measurement temperature was 25°C. The rate is calculated based on a loading of 4190mAh / g for each cell. I put it out.

[0240] From the cycle characteristics results in Figure 17, the cell with a high loading capacity is better than the cell CS1[1] with a low loading capacity. It can be seen that cell CS1[2] has a lower overall discharge capacity. The cell CS2[2] with a higher loading capacity is more efficiently discharged overall than the cell CS2[1] with a lower loading capacity. This is because the negative electrode active material is made of LTPO with silicon added, and LATP In the case of a negative electrode active material in which silicon is added to the above, the electrode layer becomes thicker as the amount of silicon loaded increases. This is thought to be due to the increased electrical resistance in the thickness direction.

[0241] In addition, for cell CS4, up to about 10 cycles, the However, after 10 cycles, the discharge capacity drops sharply. This is because the nanocrystalline silicon contained in the negative electrode active material changes depending on the number of cycles. This is thought to be because the silicon repeatedly expands and contracts, causing the nanosilicon to peel off from the electrode current collector. can be obtained.

[0242] Another reason for the sudden drop in discharge capacity is thought to be the effect of electrolyte decomposition. When nanosilicon is used as the negative electrode, the surface of the nanosilicon in contact with the electrolyte Because the product is large, the electrolyte in contact with the nanosilicon is decomposed by a chemical reaction. Therefore, a reaction product between the decomposition liquid and the nanosilicon is formed on the surface of the nanosilicon. The larger the reaction product formed, the smaller the contact area between the nanosilicon and the electrolyte. As a result, the number of lithium atoms that can be inserted and removed from the nanosilicon decreases. The discharge capacity of the cell CS4 with nanosilicon as the anode increases with repeated cycling. It is thought to have become lower.

[0243] From the results of cells CS3[1] and CS3[2], it can be seen that the discharge capacity does not increase even if the amount of support increases. It can be seen that the voltage is not as low as that of cells CS1[2] and CS2[2]. By further adding RGO to the negative electrode active material made by adding silicon to ATP, This is thought to be due to an increase in the number of conduction paths for ions or electrons within the material.

[0244] Next, the rate characteristics will be explained. 10 is a graph showing the discharge capacity versus the discharge rate for each case. FIG. 18(B) shows the results of each circuit in the cases of cell CS3[2] and cell CS5. 1 is a graph illustrating the discharge capacity ratio versus the discharge rate.

[0245] Cell CS5 used nanosilicon as the negative electrode with a loading of 0.73 mg / cm 2 Collected as This is a test cell formed on a conductive body.

[0246] In addition, Figure 18 shows the measurement results of the rate characteristics of cells CS3[2] and CS5. The graph shows the discharge capacity (mAh / g) for each of the first to sixth charges. The rates of cells CS3[2] and CS5 are 1500mA / g per charge, respectively. Specifically, the charging rate for each charge was set to 0.1C, and the first to sixth charges were calculated as follows: The discharge rates were 0.1C, 0.2C, 0.5C, 1C, 2C, and 0.1C, respectively. In other words, the discharge rate is increased from the first to fifth times, and the sixth time is the same as the first time. It is equal to the discharge rate.

[0247] As shown in FIG. 18(A)(B), in the first discharge, the cells CS5 and CS3[ The discharge capacities of [2] are 3772.35mAh / g and 2118.26mAh / g, respectively. It was.

[0248] In addition, with cell CS5, the discharge capacity decreased significantly each time the discharge rate was increased. In addition, in the sixth discharge, which is the same discharge rate as the first discharge, the discharge capacity ratio is 7 times higher than the first discharge. It has decreased by more than 0% (more than 2700mAh / g).

[0249] On the other hand, in cell CS3[2], the discharge capacity decreased as the discharge rate increased. However, it can be seen that the decrease in discharge capacity is smaller than that of cell CS5. In the second discharge, the discharge capacity was about 30% (about 680mAh / g) from the first. Although the discharge capacity decreases, the change in discharge capacity from the second to sixth discharges is approximately 10% or less. It is below.

[0250] From the above results, we can conclude that cell CS3 [2], which is a cell made by mixing nanosilicon and RGO in LATP, By constructing a secondary battery using the mixture as the negative electrode active material, the secondary battery can be cycled. The discharge capacity does not deteriorate much with the number of times it is used, and the discharge capacity ratio remains almost the same even when the discharge rate increases. It can have properties that do not deteriorate.

[0251] This embodiment can be appropriately combined with other embodiment modes shown in this specification. [Explanation of symbols]

[0252] R: Internal resistance, C: Secondary battery capacity, SW1: Switch, SW2: Switch, SW3: Switch 100: negative electrode, 101: negative electrode current collector, 102: negative electrode active material layer, 103: particles, 10 4: solid electrolyte, 105: 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, 30 7: negative electrode, 308: negative electrode current collector, 309: negative electrode active material layer, 310: separator, 600: Secondary battery, 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: insulation Plate, 610: gasket, 611: PTC element, 612: safety valve mechanism, 613: conductive plate, 614: Conductive plate, 615: Module, 616: Conductive wire, 617: Temperature control device, 700: Secondary battery, 710: Positive electrode, 711: Positive electrode active material, 713: Positive electrode current collector, 714: Positive electrode active material solid layer, 720: solid electrolyte layer, 721: solid electrolyte, 730: negative electrode, 731: negative electrode active material , 733: negative electrode current collector, 734: negative electrode active material layer, 8000: display device, 8001: housing, 8002: Display unit, 8003: Speaker unit, 8004: Secondary battery, 8021: Charging device, 8022: Cable, 8024: Secondary battery, 8100: Lighting device, 8101: Housing, 81 02: Light source, 8103: Secondary battery, 8104: Ceiling, 8105: Side wall, 8106: Floor, 8 107: window, 8200: indoor unit, 8201: housing, 8202: air outlet, 8203: secondary battery Pond, 8204: Outdoor unit, 8300: Electric refrigerator / freezer, 8301: Housing, 8302: Refrigerator Doors for use, 8303: Freezer doors, 8304: Secondary batteries, 8400: Automobiles, 8401: Heads Light, 8500: Automobile, 8600: Scooter, 8601: Side mirror, 8602 : Secondary battery, 8603: Turn signal light, 8604: Under-seat storage, 9600: Tablet type terminal End, 9625: Switch, 9626: Switch, 9627: Switch, 9628: Operation switch Switch, 9629: fastener, 9630: housing, 9630a: housing, 9630b: housing, 9 631: Display unit, 9633: Solar cell, 9634: Charge and discharge control circuit, 9635: Power storage unit, 9636: DCDC converter, 9637: converter, 9638: operation key, 9640 :Movable part

Claims

1. an electrolytic solution and a negative electrode active material layer, the negative electrode active material layer includes negative electrode active material particles, a solid electrolyte, and a graphene compound, the negative electrode active material particles contain silicon, the surfaces of the negative electrode active material particles have a reaction product between the silicon and the decomposition solution of the electrolyte, the solid electrolyte comprises lithium, titanium, phosphorus, and oxygen; The graphene compound has reduced graphene oxide, the negative electrode active material particles and the solid electrolyte form secondary particles, The secondary particles have voids, In the SEM observation image of the secondary particles, silicon, oxygen, phosphorus, and titanium are uniformly dispersed. Secondary battery.

2. an electrolytic solution and a negative electrode active material layer, the negative electrode active material layer includes negative electrode active material particles, a solid electrolyte, and a graphene compound, the negative electrode active material particles contain silicon, the surfaces of the negative electrode active material particles have a reaction product between the silicon and the decomposition solution of the electrolyte, the solid electrolyte comprises lithium, titanium, phosphorus, and oxygen; The graphene compound has graphene oxide, the negative electrode active material particles and the solid electrolyte form secondary particles, The secondary particles have voids, In the SEM observation image of the secondary particles, silicon, oxygen, phosphorus, and titanium are uniformly dispersed. Secondary battery.

3. In claim 1 or claim 2, The primary particle size of the negative electrode active material particles is 10 nm or more and 100 nm or less. Secondary battery.

4. an electrolytic solution and a negative electrode active material layer, the negative electrode active material layer includes nanosilicon, a solid electrolyte, and a graphene compound, the surface of the nanosilicon has a reaction product between the nanosilicon and the decomposition solution of the electrolyte; the solid electrolyte comprises lithium, titanium, phosphorus, and oxygen; The graphene compound has reduced graphene oxide, the nanosilicon and the solid electrolyte form secondary particles, The secondary particles have voids, In the SEM observation image of the secondary particles, silicon, oxygen, phosphorus, and titanium are uniformly dispersed. Secondary battery.

5. an electrolytic solution and a negative electrode active material layer, the negative electrode active material layer includes nanosilicon, a solid electrolyte, and a graphene compound, the surface of the nanosilicon has a reaction product between the nanosilicon and the decomposition solution of the electrolyte; the solid electrolyte comprises lithium, titanium, phosphorus, and oxygen; The graphene compound has graphene oxide, the nanosilicon and the solid electrolyte form secondary particles, The secondary particles have voids, In the SEM observation image of the secondary particles, silicon, oxygen, phosphorus, and titanium are uniformly dispersed. Secondary battery.

6. In any one of claims 1 to 3, A plurality of diffraction peaks are observed by powder XRD measurement of the secondary particles, The plurality of diffraction peaks include a peak that can be identified as silicon, a peak that can be identified as the solid electrolyte, and a peak at 2θ=24.1±0.1°. Secondary battery.

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