JP6575109B2 - Lithium ion conductor, electrode, battery, manufacturing method thereof, and electronic device - Google Patents

Description

  The present technology relates to a lithium ion conductor, an electrode, a battery, a manufacturing method thereof, and an electronic device.

  An inorganic solid electrolyte is a material that is excellent in safety and has a low environmental impact, and is expected to be applied to an all-solid battery. A lithium ion conductive solid electrolyte currently considered to be applicable to batteries is lithium phosphate titanate.

For example, Patent Document 1 proposes a lithium phosphate titanate whose average composition is represented by the following formula.
Li _{1 + x} M1 _x Ti _2-x (PO ₄ ) ₃
Wherein M1 is from the group consisting of aluminum (Al), scandium (Sc), indium (In), iron (Fe), chromium (Cr), gallium (Ga), yttrium (Y), and lanthanum (La). Represents at least one selected, the value of x is in the range of 0 ≦ x ≦ 2.0.)

JP 2009-181807 A

  However, since lithium phosphate titanate has a high sintering temperature, there is a possibility that battery characteristics are deteriorated in the sintering process of lithium phosphate titanate.

  An object of the present technology is to provide a lithium ion conductor that can be sintered at a low temperature, an electrode, a battery, a manufacturing method thereof, and an electronic apparatus.

To solve the problems described above, the first technique consists of a least one of S iO _2, B ₂ O ₃ and P ₂ O _5, and Li ₂ O, the content of Li ₂ O 20 mol It is a lithium ion conductor that is not less than 75% and not more than 75 mol%.

  The second technique is an electrode including the lithium ion conductor and an active material.

  A third technique is a battery that includes a positive electrode, a negative electrode, and an electrolyte, and at least one of the negative electrode, the positive electrode, and the electrolyte includes the lithium ion conductor.

  A fourth technique is an electronic device that includes the battery and receives power supply from the battery.

The fifth technique includes laminating a positive electrode precursor, a solid electrolyte precursor, and a negative electrode precursor to form a laminated body, and firing the laminated body at 600 ° C. or lower. The positive electrode precursor, the solid electrolyte precursor, and at least one of the negative electrode _{precursor, S iO 2, B 2 O} 3 and P ₂ and one or more of O _5, wherein the lithium ion conductor consisting of Li ₂ O, 20mol% is the Li ₂ O content This is a method for producing a battery of 75 mol% or less.

  As described above, according to the present technology, a lithium ion conductor that can be sintered at a low temperature can be provided.

FIG. 1 is a cross-sectional view illustrating a configuration example of a battery according to the second embodiment of the present technology. FIG. 2A is a cross-sectional view illustrating a configuration example of a battery according to a modification of the second embodiment of the present technology. FIG. 2B is a cross-sectional view illustrating a configuration example of a battery according to another modification of the second embodiment of the present technology. FIG. 3 is a block diagram illustrating a configuration example of an electronic device according to the third embodiment of the present technology. FIG. 4A is a graph showing a Cole-Cole plot of the solid electrolyte layer of Example 1-2. FIG. 4B is a graph showing a Cole-Cole plot of the solid electrolyte layer of Example 1-3. 5A and 5B are graphs showing the temperature dependence of the lithium ion conductivity of the solid electrolyte layer of Example 2-1. FIG. 6A is a graph showing a measurement result of an X-ray diffraction spectrum of a Li—Si—B—O-based solid electrolyte powder before firing. FIG. 6B is a graph showing the measurement results of the X-ray diffraction spectrum of the Li—Si—B—O-based solid electrolyte powder after firing. FIG. 7A is a graph showing a measurement result of an X-ray diffraction spectrum of LiCoO ₂ powder. FIG. 7B is a graph showing the measurement results of the X-ray diffraction spectrum of the fired positive electrode mixture powder (mixed powder of LiCoO ₂ powder and Li—Si—B—O-based solid electrolyte powder). FIG. 8A is a graph showing the measurement results of the X-ray diffraction spectrum of the positive electrode mixture powder (mixed powder of Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ powder and LiMn ₂ O ₄ powder) before firing. FIG. 8B is a graph showing the measurement result of the X-ray diffraction spectrum of the positive electrode mixture powder (Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ powder and LiMn ₂ O ₄ powder mixed powder) after firing. FIG. 9A is a graph showing the results of thermogravimetric analysis of the negative electrode of Example 4-1. FIG. 9B is a graph showing the results of thermomechanical analysis of the negative electrode of Example 4-1. FIG. 10A is a graph showing the results of thermogravimetric analysis of the negative electrode of Comparative Example 4-1. FIG. 10B is a graph showing the results of thermomechanical analysis of the negative electrode of Comparative Example 4-1. FIG. 11A is an SEM image of the negative electrode green sheet before firing. FIG. 11B is an SEM image of the negative electrode green sheet after firing. FIG. 11C is a graph showing a charge / discharge curve of the all-solid-state battery of Example 5-1. FIG. 12A is an SEM image of the positive green sheet before firing. FIG. 12B is an SEM image of the positive electrode green sheet after firing. FIG. 12C is a graph showing a charge / discharge curve of the all-solid-state battery of Example 6-1.

Embodiments of the present technology will be described in the following order.
1. First embodiment (example of lithium ion conductor)
1.1 Configuration of Lithium Ion Conductor 1.2 Method for Producing Lithium Ion Conductor 1.3 Effect 1.4 Modification 2 Second Embodiment (Example of Battery)
2.1 Battery Configuration 2.2 Battery Manufacturing Method 2.3 Effects 2.4 Modifications Third Embodiment (Example of Electronic Device)
3.1 Configuration of electronic device 3.2 Modification

<1 First Embodiment>
[1.1 Structure of lithium ion conductor]
The lithium ion conductor according to the first embodiment of the present technology is a powder, and one or more of Ge (germanium), Si (silicon), B (boron), and P (phosphorus), and Li (lithium) And O (oxygen). Specifically, at least one of GeO ₂ , SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O are included. The form of the lithium ion conductor is not limited to powder, and may be a thin film or a block.

  The lithium ion conductor according to the first embodiment is suitable for use in an electrochemical device. The electrochemical device may be basically any device, and specifically, for example, various batteries using Li or the like, a capacitor, a gas sensor, a Li ion filter, or the like. The battery is, for example, a primary battery, a secondary battery, an air battery, a fuel cell, or the like. The secondary battery is, for example, a lithium ion battery, and an all solid lithium ion battery can be realized by using the lithium ion conductor according to the first embodiment as a solid electrolyte. However, the lithium ion conductor according to the first embodiment can be used for both an all-solid battery and a liquid battery.

  When the lithium ion conductor according to the first embodiment is applied to a battery, it can be used as, for example, a solid electrolyte, a binder, or a coating agent of the battery. Note that the lithium ion conductor according to the first embodiment can be used as a material having two or more functions of a solid electrolyte, a binder, and a coating agent.

  Specifically, for example, the solid electrolyte layer may be formed using the lithium ion conductor according to the first embodiment, or the lithium ion conductor according to the first embodiment may be formed as a solid electrolyte and / or a binder. You may make it contain in an electrode or an active material layer as an agent.

  Further, using the lithium ion conductor according to the first embodiment, a ceramic green sheet (hereinafter simply referred to as “green sheet”) or pressure as a solid electrolyte layer precursor, an electrode layer precursor or an active material layer precursor. Powder may be formed, and a sintered body as a solid electrolyte layer, an electrode, or an active material layer may be formed.

Moreover, you may use the lithium ion conductor which concerns on 1st Embodiment as a surface coating agent in order to coat | cover at least one part of the surface of electrode active material particle. In this case, the reaction between the electrolytic solution and the electrode active material can be suppressed. For example, when used as a surface coating agent for positive electrode active material particles such as LCO (LiCoO ₂ ) and NCM (Li [NiMnCo] O ₂ ), oxygen release from the positive electrode active material particles can be suppressed. it can.

  In the sulfur-based all solid state battery, the lithium ion conductor according to the first embodiment may be used as a surface coating agent for the electrode active material particles in order to suppress the reaction between the electrode active material and the sulfur-based solid electrolyte.

  Further, the lithium ion conductor according to the first embodiment may be used as an additive for adding to the battery separator, or as a coating agent for coating the surface of the battery separator. In this case, the safety of the battery can be improved.

  The lithium ion conductor according to the first embodiment is, for example, amorphous (amorphous), crystalline, or a mixture of amorphous and crystalline. Here, the crystalline includes not only a single crystal but also a polycrystal in which a large number of crystal grains are aggregated. Crystalline means a crystallographic state such as a single crystal or a polycrystal such as a peak observed in X-ray diffraction or electron beam diffraction. Amorphous means a state that is amorphous in terms of crystallography, such as halo observed in X-ray diffraction or electron beam diffraction. A mixture of amorphous and crystalline means a state in which amorphous and crystalline are mixed crystallographically, such as peaks and halos observed in X-ray diffraction and electron beam diffraction. .

  The sintering temperature of the lithium ion conductor according to the first embodiment is preferably 600 ° C. or lower, more preferably 300 ° C. or higher and 600 ° C. or lower, and further preferably 300 ° C. or higher and 500 ° C. or lower. It can suppress that a lithium ion conductor and an electrode active material react in a baking process (sintering process) as the sintering temperature is 600 degrees C or less, and by-products, such as a nonconductor, are formed. Accordingly, it is possible to suppress a decrease in battery characteristics. Moreover, since the selection range of the kind of electrode active material is expanded, the freedom degree of battery design can be improved. When the sintering temperature is 500 ° C. or lower, a carbon material can be used as the negative electrode active material. Therefore, the energy density of the battery can be improved. In addition, since a carbon material can be used as the conductive agent, a favorable electron conduction path can be formed in the electrode layer or the electrode active material layer, and the conductivity of the electrode layer or the electrode active material layer can be improved. On the other hand, when the sintering temperature is 300 ° C. or higher, an organic binder such as an acrylic resin contained in the electrode precursor and / or the solid electrolyte precursor can be burned out in the firing step (sintering step). .

The content of Li ₂ O is 20 mol% or more and 75 mol% or less, preferably more than 25 mol% and 75 mol% or less, more preferably 30 mol% or more and 75 mol% or less, still more preferably 40 mol% or more and 75 mol% or less, particularly preferably 50 mol%. % Or more and 75 mol% or less. If the lithium ion conductor containing GeO _2, the content of the GeO ₂ is preferably less 80 mol% exceed 0 mol%. If the lithium ion conductor comprises SiO _2, the content of the SiO ₂ is preferably at most 70 mol% exceed 0 mol%. If the lithium ion conductor comprises a B ₂ O _3, the content of the B ₂ O ₃ is preferably not more than 60 mol% exceed 0 mol%. If the lithium ion conductor comprises a P ₂ O _5, the content of the P ₂ O ₅ is preferably less 50 mol% exceed 0 mol%. The content of each oxide is the content of each oxide in a lithium ion conductor in, specifically, one of _{GeO 2, SiO 2, B 2} O 3 and P ₂ O ₅ The ratio of the content (mol) of each oxide to the total amount (mol) with Li ₂ O is shown as a percentage (mol%). The content of each oxide can be measured using inductively coupled plasma emission spectroscopy (ICP-AES) or the like.

  The lithium ion conductor according to the first embodiment may further contain an additional element as necessary. Examples of the additive element include Na (sodium), Mg (magnesium), Al (aluminum), K (potassium), Ca (calcium), Ti (titanium), V (vanadium), Cr, Mn (manganese), and Fe. , Co (cobalt), Ni (nickel), Cu (copper), Zn (zinc), Ga, Se (selenium), Rb (rubidium), S (sulfur), Y, Zr (zirconium), Nb (niobium), Mo (molybdenum), Ag (silver), In (indium), Sn (tin), Sb (antimony), Cs (cesium), Ba (vanadium), Hf (hafnium), Ta (tantalum), W (tungsten), One or more selected from the group consisting of Pb (lead), Bi (bismuth), Au (gold), La, Nd (neodymium), and Eu (europium) can be mentioned. The lithium ion conductor according to the first embodiment may contain one or more selected from the group consisting of these additive elements as an oxide.

[1-2 Lithium ion conductor production method]
Hereinafter, an example of the manufacturing method of the lithium ion conductor which concerns on 1st Embodiment of this technique is demonstrated.

First, Li ₂ O is mixed as a raw material with at least one of GeO ₂ , SiO ₂ , B ₂ O ₃ and P ₂ O ₅ . The blending amounts of these GeO ₂ , SiO ₂ , B ₂ O ₃ , P ₂ O ₅ and Li ₂ O are, for example, the same as the content of these materials in the above-described lithium ion conductor. In addition, you may further mix the said additional element or its oxide as a raw material as needed.

  Next, a lithium ion conductor is produced by vitrifying the raw material. As a method for vitrifying the raw material, for example, a method in which the raw material is melted to a melt and allowed to cool, a method in which the melt is pressed with a metal plate, a method in which the melt is dropped into mercury, a strip furnace, a splat quench, a roll method ( In addition to single and twin), mechanical milling method, sol-gel method, vapor deposition method, sputtering method, laser ablation method, PLD (pulse laser deposition) method, plasma method and the like can be mentioned.

  Next, the lithium ion conductor is pulverized. Examples of the powdering method include a mechanochemical method. As described above, the target lithium ion conductor powder is obtained.

[1.3 Effect]
The powder of the lithium ion conductor according to the first embodiment includes at least one of GeO ₂ , SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O, and the content of Li ₂ O Is 20 mol% or more and 75 mol% or less. For this reason, the powder of the lithium ion conductor according to the first embodiment can be sintered at a low temperature. Therefore, when producing an electrode using the lithium ion conductor which concerns on 1st Embodiment, reaction with an electrode active material and a lithium ion conductor can be suppressed, and the fall of a battery characteristic can be suppressed. Moreover, since the selection range of the type of electrode active material is expanded, the degree of freedom in battery design is increased. In addition, since the firing temperature (sintering temperature) in the battery manufacturing process can be lowered, the battery manufacturing cost can be reduced.

  The lithium ion conductor according to the first embodiment can be used as an inorganic solid electrolyte. Inorganic solid electrolytes are superior to organic solid electrolytes in terms of potential window, Li ion transport number, safety (nonflammability), and the like.

[1.4 Modification]
The lithium ion conductor may contain two or more, three or more, or all four of Ge, Si, B, and P, Li, and O. Specifically, two or more, three or more, or all four of GeO ₂ , SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O may be included.

<2 Second Embodiment>
In the second embodiment, a battery including the sintered body of the lithium ion conductor according to the first embodiment described above as a solid electrolyte in a positive electrode, a negative electrode, and a solid electrolyte layer will be described.

[2.1 Battery configuration]
The battery according to the second embodiment of the present technology is a so-called bulk type all-solid battery, and includes a positive electrode 11, a negative electrode 12, and a solid electrolyte layer 13, as shown in FIG. And the negative electrode 12. This battery is a secondary battery obtained by repeatedly receiving and transferring Li, which is an electrode reactant, and may be a lithium ion secondary battery in which the capacity of the negative electrode is obtained by occlusion and release of lithium ions, It may be a lithium metal secondary battery in which the capacity of the negative electrode is obtained by precipitation dissolution of lithium metal.

(Positive electrode)
The positive electrode 11 is a positive electrode active material layer containing one or more positive electrode active materials and a solid electrolyte. The solid electrolyte may have a function as a binder. The positive electrode 11 may further include a conductive agent as necessary. The positive electrode 11 is, for example, a fired body of a green sheet (hereinafter referred to as “positive electrode green sheet”) as a positive electrode precursor.

  The positive electrode active material includes, for example, a positive electrode material capable of occluding and releasing lithium ions that are electrode reactants. The positive electrode material is preferably a lithium-containing compound or the like from the viewpoint of obtaining a high energy density, but is not limited thereto. This lithium-containing compound is, for example, a composite oxide (lithium transition metal composite oxide) containing lithium and a transition metal element as constituent elements, or a phosphate compound (lithium transition metal) containing lithium and a transition metal element as constituent elements. Phosphate compounds). Among them, the transition metal element is preferably one or more of Co, Ni, Mn, and Fe. This is because a higher voltage can be obtained.

The lithium transition metal composite oxide is represented by, for example, Li _x M1O ₂ or Li _y M2O ₄ . More specifically, for example, the lithium transition metal composite oxide is LiCoO ₂ , LiNiO ₂ , LiVO ₂ , LiCrO _2, or LiMn ₂ O ₄ . Further, the lithium transition metal phosphate compound is represented by, for example, Li _z M3PO ₄ . More specifically, for example, the lithium transition metal phosphate compound is LiFePO ₄ or LiCoPO ₄ . However, M1 to M3 are one kind or two or more kinds of transition metal elements, and the values of x to z are arbitrary.

  In addition, the positive electrode active material may be, for example, an oxide, disulfide, chalcogenide, or conductive polymer. Examples of the oxide include titanium oxide, vanadium oxide, and manganese dioxide. Examples of the disulfide include titanium disulfide and molybdenum sulfide. An example of the chalcogenide is niobium selenide. Examples of the conductive polymer include sulfur, polyaniline, and polythiophene.

  The positive electrode active material is a powder of positive electrode active material particles. The surface of the positive electrode active material particles may be coated with a coating agent. Here, the coating is not limited to the entire surface of the positive electrode active material particles, and may be a part of the surface of the positive electrode active material particles. The coating agent is at least one of a solid electrolyte and a conductive agent, for example. By covering the surfaces of the positive electrode active material particles with a coating agent, the interface resistance between the positive electrode active material particles and the solid electrolyte can be reduced. In addition, since the collapse of the structure of the positive electrode active material particles can be suppressed, the sweep potential width can be widened so that more lithium can be used for the reaction, and the cycle characteristics can be improved.

  The solid electrolyte is a sintered body of the lithium ion conductor according to the first embodiment described above. The sintered body of the lithium ion conductor is, for example, amorphous, crystalline, or a mixture of amorphous and crystalline. The solid electrolyte as the coating agent for the positive electrode active material particles may also be a sintered body of the lithium ion conductor according to the first embodiment described above.

The conductive agent includes, for example, a carbon material, a metal, a metal oxide, a conductive polymer, or the like alone or in combination. As the carbon material, for example, graphite, carbon fiber, carbon black, carbon nanotube and the like can be used alone or in combination of two or more. As the carbon fiber, for example, vapor growth carbon fiber (VGCF) can be used. As carbon black, acetylene black, Ketjen black, etc. can be used, for example. As the carbon nanotube, for example, a multi-wall carbon nanotube (MWCNT) such as a single wall carbon nanotube (SWCNT) or a double wall carbon nanotube (DWCNT) can be used. As the metal, for example, Ni powder can be used. For example, SnO ₂ can be used as the metal oxide. As the conductive polymer, for example, substituted or unsubstituted polyaniline, polypyrrole, polythiophene, and one or two (co) polymers selected from these can be used. Note that the conductive agent may be any material having conductivity, and is not limited to the above example.

(Negative electrode)
The negative electrode 12 is a negative electrode active material layer containing one type or two or more types of negative electrode active materials and a solid electrolyte. The solid electrolyte may have a function as a binder. The negative electrode 12 may further contain a conductive agent as necessary. The negative electrode 12 is, for example, a fired body of a green sheet (hereinafter referred to as “negative electrode green sheet”) as a negative electrode precursor.

  The negative electrode active material includes, for example, a negative electrode material capable of occluding and releasing lithium ions that are electrode reactants. The negative electrode material is preferably a carbon material or a metal-based material from the viewpoint of obtaining a high energy density, but is not limited thereto.

  Examples of the carbon material include graphitizable carbon, non-graphitizable carbon, graphite, mesocarbon microbeads (MCMB), and highly oriented graphite (HOPG).

The metal-based material is a material containing, for example, a metal element or a metalloid element capable of forming an alloy with lithium as a constituent element. More specifically, the metal-based material is, for example, Si, Sn, Al, In, Mg, B, Ga, Ge, Pb, Bi, Cd (cadmium), Ag, Zn, Hf, Zr, Y, Pd ( One or two or more of a simple substance such as palladium) or Pt (platinum), an alloy, or a compound. However, the simple substance is not limited to 100% purity, and may contain a small amount of impurities. Specific examples of the metal material include Si, Sn, SiB ₄ , TiSi ₂ , SiC, Si ₃ N ₄ , SiO _v (0 <v ≦ 2), LiSiO, SnO _w (0 <w ≦ 2), SnSiO _3. , LiSnO, Mg ₂ Sn and the like.

The metal-based material may be a lithium-containing compound or lithium metal (lithium simple substance). The lithium-containing compound is a composite oxide (lithium transition metal composite oxide) containing lithium and a transition metal element as constituent elements. Examples of this composite oxide include Li ₄ Ti ₅ O ₁₂ .

  The negative electrode active material is a powder of negative electrode active material particles. The surface of the negative electrode active material particles may be coated with a coating agent. Here, the coating is not limited to the entire surface of the negative electrode active material particles, and may be a part of the surface of the negative electrode active material particles. The coating agent is at least one of a solid electrolyte and a conductive agent, for example. By covering the surface of the negative electrode active material particles with a coating agent, the interface resistance between the negative electrode active material particles and the solid electrolyte can be reduced. In addition, since the collapse of the structure of the negative electrode active material particles can be suppressed, the sweep potential width can be widened so that a large amount of lithium can be used for the reaction, and the cycle characteristics can be improved.

  The solid electrolyte is a sintered body of the lithium ion conductor according to the first embodiment described above. The sintered body of the lithium ion conductor is, for example, amorphous, crystalline, or a mixture of amorphous and crystalline. The solid electrolyte as the coating agent for the negative electrode active material particles may also be a sintered body of the lithium ion conductor according to the first embodiment described above.

  The conductive agent is the same as the conductive agent in the positive electrode 11 described above.

(Solid electrolyte layer)
The solid electrolyte layer 13 includes the sintered body of the lithium ion conductor according to the first embodiment described above. The sintered body of the lithium ion conductor is, for example, amorphous, crystalline, or a mixture of amorphous and crystalline. The solid electrolyte layer 13 is, for example, a fired body of a green sheet (hereinafter referred to as “solid electrolyte green sheet”) as a solid electrolyte layer precursor.

(Battery operation)
In this battery, for example, at the time of charging, lithium ions released from the positive electrode 11 are taken into the negative electrode 12 through the solid electrolyte layer 13, and at the time of discharging, lithium ions released from the negative electrode 12 are taken into the solid electrolyte layer 13. Is taken into the positive electrode 11.

[2.2 Battery Manufacturing Method]
Next, an example of a method for manufacturing a battery according to the second embodiment of the present technology will be described. This manufacturing method includes a step of forming a positive electrode precursor, a negative electrode precursor, and a solid electrolyte layer precursor, and a step of laminating and firing these precursors. In this battery manufacturing method, a case where the positive electrode precursor, the negative electrode precursor, and the solid electrolyte layer precursor all include the lithium ion conductor according to the first embodiment will be described as an example.

(Formation process of positive electrode precursor)
A positive electrode green sheet as a positive electrode precursor is formed as follows. First, a positive electrode active material, a lithium ion conductor (solid electrolyte) according to the first embodiment, an organic binder, and a conductive agent as necessary are mixed to form a positive electrode mixture as a raw material powder. After preparing the powder, the positive electrode mixture powder is dispersed in an organic solvent or the like to obtain a positive electrode slurry as a positive electrode green sheet forming composition. In addition, in order to improve the dispersibility of positive mix powder, dispersion | distribution may be performed in several times.

  As the organic binder, for example, an organic binder such as an acrylic resin can be used. The solvent is not particularly limited as long as it can disperse the positive electrode mixture powder, but is preferably one that burns away in a temperature range lower than the firing temperature of the green sheet. Examples of the solvent include lower alcohols having 4 or less carbon atoms such as methanol, ethanol, isopropanol, n-butanol, sec-butanol, t-butanol, ethylene glycol, propylene glycol (1,3-propanediol), 1, Aliphatic glycols such as 3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, ketones such as methyl ethyl ketone, dimethylethylamine Amines such as alicyclic alcohols such as terpineol can be used alone or in admixture of two or more, but the invention is not particularly limited thereto. Examples of the dispersion method include stirring treatment, ultrasonic dispersion treatment, bead dispersion treatment, kneading treatment, and homogenizer treatment.

  Next, if necessary, the positive electrode slurry may be filtered with a filter to remove foreign substances in the positive electrode slurry. Next, if necessary, vacuum deaeration may be performed on the positive electrode slurry to remove internal bubbles.

  Next, for example, the positive electrode slurry layer is formed by uniformly applying or printing the positive electrode slurry on the surface of the support substrate. As the support substrate, for example, a polymer resin film such as polyethylene terephthalate (PET) can be used. As a coating or printing method, it is preferable to use a simple and suitable method for mass production. Examples of coating methods include die coating, micro gravure coating, wire bar coating, direct gravure coating, reverse roll coating, comma coating, knife coating, spray coating, curtain coating, dipping, and spin. A coating method or the like can be used, but is not particularly limited thereto. As a printing method, for example, a relief printing method, an offset printing method, a gravure printing method, an intaglio printing method, a rubber plate printing method, a screen printing method, and the like can be used, but the invention is not particularly limited thereto.

  In order to make it easier to peel the positive electrode green sheet from the surface of the supporting substrate in a subsequent step, it is preferable to perform a peeling treatment on the surface of the supporting substrate in advance. As a peeling process, the method of apply | coating or printing in advance on the surface of a support base material is mentioned, for example. Examples of the composition that imparts releasability include paints containing a binder as a main component and added with wax, fluorine, or the like, or silicone resins.

  Next, a positive electrode green sheet is formed on the surface of the support substrate by drying the positive electrode slurry layer. Examples of the drying method include natural drying, blow drying with hot air, heating drying with infrared rays or far infrared rays, vacuum drying, and the like. These drying methods may be used alone or in combination of two or more.

(Formation process of negative electrode precursor)
A negative electrode green sheet as a negative electrode precursor is formed as follows. First, a negative electrode active material, a lithium ion conductor (solid electrolyte) according to the first embodiment, an organic binder, and, if necessary, a conductive agent are mixed to form a negative electrode mixture as a raw material powder. After preparing the powder, the negative electrode mixture powder is dispersed in an organic solvent or the like to obtain a negative electrode slurry as a negative electrode green sheet forming composition. Except for using this negative electrode slurry, a negative electrode green sheet is obtained in the same manner as in the “positive electrode precursor forming step” described above.

(Solid electrolyte precursor formation process)
A solid electrolyte green sheet as a solid electrolyte layer precursor is formed as follows. First, the lithium ion conductor (solid electrolyte) according to the first embodiment and an organic binder are mixed to prepare an electrolyte mixture powder as a raw material powder. Disperse in a solvent or the like to obtain an electrolyte mixture slurry as a solid electrolyte green sheet forming composition. A solid electrolyte green sheet is obtained in the same manner as in the “positive electrode precursor forming step” except that this electrolyte mixture slurry is used.

(Precursor lamination and firing step)
Using the positive electrode green sheet, the negative electrode green sheet, and the solid electrolyte green sheet obtained as described above, a battery is manufactured as follows. First, a positive electrode green sheet and a negative electrode green sheet are laminated to sandwich a solid electrolyte green sheet. Then, while heating a laminated body, a laminated body is pressed so that a pressure may be applied to the thickness direction of a laminated body at least. Thereby, the organic binder contained in each green sheet constituting the laminate is melted, and the green sheets constituting the laminate are brought into close contact with each other. Specific methods for pressing the laminate while heating include, for example, a hot press method, a warm isostatic press (WIP), and the like.

  Next, the laminate is cut into a predetermined size and shape as necessary. Next, by firing the laminate, the lithium ion conductor contained in each green sheet constituting the laminate is sintered and the organic binder is burned out.

  The firing temperature of the laminate is not less than the sintering temperature of the lithium ion conductor, preferably not less than the sintering temperature of the lithium ion conductor and not more than 600 ° C., more preferably not less than the sintering temperature of the lithium ion conductor. Here, the sintering temperature of a lithium ion conductor means the sintering temperature of the lithium ion conductor when the lithium ion conductor contained in the laminate is one kind. On the other hand, when there are two or more types of lithium ion conductors included in the laminate, it means the maximum of the sintering temperatures of those lithium ion conductors.

  When the firing temperature of the laminate is equal to or higher than the sintering temperature of the lithium ion conductor, the lithium ion conductor proceeds, so that the lithium ion conductivity of the positive electrode, the negative electrode, and the solid electrolyte layer can be improved. Moreover, the intensity | strength of a positive electrode, a negative electrode, and a solid electrolyte layer can be raised. The reason why the firing temperature of the laminate is 600 ° C. or lower or 500 ° C. or lower is the same as the reason for setting the sintering temperature of the lithium ion conductor described in the first embodiment to 600 ° C. or lower or 500 ° C. or lower.

  In the case where the lithium ion conductor contained in the laminate is amorphous before the firing step, the lithium ion conductor may be crystalline or a mixture of amorphous and crystalline in the firing step. Moreover, when the lithium ion conductor contained in the laminate before the firing step is a mixture of amorphous and crystalline, the lithium ion conductor may be crystalline in the firing step. Thus, the target battery is obtained.

[2.3 Effects]
In the second embodiment of the present technology, the solid electrolyte contained in the positive electrode green sheet, the negative electrode green sheet, and the solid electrolyte green sheet is the lithium ion conductor according to the first embodiment, that is, lithium ion conduction that can be sintered at a low temperature. Is the body. Therefore, the firing temperature of the positive electrode green sheet, the negative electrode green sheet, and the solid electrolyte green sheet can be lowered. Thereby, the damage of the positive electrode active material and the negative electrode active material in the baking process of a laminated body can be suppressed, and the fall of a battery characteristic can be suppressed. In addition, the selection range of the positive electrode active material and the negative electrode active material is widened, and the degree of freedom in battery design is improved.

  A positive electrode green sheet, a negative electrode green sheet, and a solid electrolytic green sheet can be collectively fired at a low temperature to produce an all-solid battery. Therefore, the interface resistance between the positive electrode 11 and the solid electrolyte layer 13 and the interface resistance between the negative electrode 12 and the solid electrolyte layer 13 are reduced while suppressing damage to the positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13 due to firing. Can do.

  Since the lithium ion conductor according to the first embodiment is sintered in the positive electrode 11 and the negative electrode 12, the film strength of the positive electrode 11 and the negative electrode 12 is high. Therefore, even when the layer thickness of the positive electrode 11 and the negative electrode 12 is increased, the battery performance can be maintained.

  By producing an all-solid-state battery using the green sheet process, members such as exterior materials that do not contribute to the battery capacity are eliminated, or the battery capacity is increased compared to general cylindrical, square, or stack type lithium ion batteries. Members such as exterior materials that do not contribute can be reduced. Therefore, the occupation ratio of the positive electrode active material and the negative electrode active material with respect to the entire battery or battery pack can be increased, and the battery capacity (energy density) can be improved.

  Since a solid electrolyte is used as the electrolyte, safety is improved. For this reason, a battery structure, a control circuit, etc. can be simplified. Therefore, the volume energy density and weight energy density of the battery are improved.

[2.4 Modification]
In the above-described second embodiment, the example in which the positive electrode and the negative electrode are each composed of only the positive electrode active material layer and the negative electrode active material layer has been described. However, the configurations of the positive electrode and the negative electrode are not limited thereto. For example, as shown in FIG. 2A, the positive electrode 21 may include a positive electrode current collector 21A and a positive electrode active material layer 21B provided on one surface of the positive electrode current collector 21A. The negative electrode 22 may include a negative electrode current collector 22A and a negative electrode active material layer 22B provided on one surface of the negative electrode current collector 22A. In this case, the positive electrode 21 and the negative electrode 22 are laminated via the solid electrolyte layer 13 so that the positive electrode active material layer 21B and the negative electrode active material layer 22B face each other. In addition, the same code | symbol is attached | subjected to the location similar to the above-mentioned 2nd Embodiment, and description is abbreviate | omitted.

  The positive electrode current collector 21A includes, for example, a metal such as Al, Ni, and stainless steel. The shape of the positive electrode current collector 21A is, for example, a foil shape, a plate shape, or a mesh shape. The positive electrode active material layer 21B is the same as the positive electrode (positive electrode active material layer) 11 in the second embodiment.

  The negative electrode current collector 22A includes, for example, a metal such as Cu or stainless steel. The shape of the anode current collector 22A is, for example, a foil shape, a plate shape, or a mesh shape. The negative electrode active material layer 22B is the same as the negative electrode (negative electrode active material layer) 12 in the second embodiment.

  Note that one of the positive electrode 21 and the negative electrode 22 may include a current collector and an active material layer, and the other may include only an active material layer.

  As shown in FIG. 2B, the battery includes a laminated body including a positive electrode 31, a negative electrode 32 provided on both surfaces of the positive electrode 31, and a solid electrolyte layer 13 provided between the positive electrode 31 and the negative electrode 32. It is good. The battery may further include an exterior material 33 at both ends of the laminate. The solid electrolyte layer 13 may cover the laminate surface. In this case, the solid electrolyte layer 13 is provided so as to cover one end face of the negative electrode 32, and the solid electrolyte layer 13 on the surface of the laminate and the solid electrolyte layer 13 provided between the positive electrode 31 and the negative electrode 32 are provided. It may be connected. The solid electrolyte layer 13 may be provided so as to cover the other end face of the positive electrode 31, and the solid electrolyte layer 13 provided on both surfaces of the positive electrode 31 may be connected. In addition, the same code | symbol is attached | subjected to the location similar to the above-mentioned modification, and description is abbreviate | omitted.

  The positive electrode 31 includes a positive electrode current collector 21A and a positive electrode active material layer 21B provided on both surfaces of the positive electrode current collector 21A. The negative electrode 32 includes a negative electrode current collector 22A and a negative electrode active material layer 22B provided on one surface of the negative electrode current collector 22A. The packaging material 33 is made of a resin material such as an acrylic resin.

  In the above-described second embodiment, the example in which the present technology is applied to the battery using lithium as the electrode reactant is described, but the present technology is not limited to this example. For example, the present technology may be applied to a battery using another alkali metal such as Na or K, an alkaline earth metal such as Mg or Ca, or another metal such as Al or Ag as an electrode reactant.

  In the second embodiment described above, the case where the positive electrode precursor, the negative electrode precursor, and the solid electrolyte layer precursor are green sheets has been described as an example. However, the positive electrode precursor, the negative electrode precursor, and the solid electrolyte layer precursor are pressurized. Powder may be sufficient. Of the positive electrode precursor, the negative electrode precursor, and the solid electrolyte layer precursor, one or two layers of precursors may be green sheets, and the rest may be green compacts. The green compact as the positive electrode precursor is produced by pressure-molding the positive electrode mixture powder with a press or the like. The green compact as the negative electrode precursor is produced by pressure-molding the negative electrode mixture powder with a press or the like. The green compact as the solid electrolyte layer precursor is produced by pressure-molding the electrolyte mixture powder with a press or the like. Note that the positive electrode mixture powder, the negative electrode mixture powder, and the electrolyte mixture powder may not contain an organic binder.

  In the second embodiment, the example in which the positive electrode precursor, the solid electrolyte layer precursor, and the negative electrode precursor are stacked and then fired has been described. However, the positive electrode precursor, the solid electrolyte layer precursor, and the negative electrode precursor are fired. Then, after forming a fired body (sintered body), these fired bodies may be laminated to form a laminated body. In this case, the laminate may not be fired after pressing the laminate, or the laminate may be fired after pressing the laminate as necessary.

  Of the positive electrode precursor, the solid electrolyte layer precursor, and the negative electrode precursor, one or two layers of precursors are pre-fired to obtain a fired body (sintered body), and the remaining layers are the unfired precursors. Alternatively, the fired body and the precursor may be laminated to form a laminated body. In this case, it is preferable to fire the laminate after pressing the laminate.

  Two layers of the positive electrode precursor, the solid electrolyte layer precursor, and the negative electrode precursor may be laminated and fired in advance, and the remaining unfired layer may be laminated on this laminate to form a laminate. . In this case, it is preferable to fire the laminate after pressing the laminate.

  Two precursors of the positive electrode precursor, the solid electrolyte layer precursor and the negative electrode precursor are laminated and fired in advance, and the remaining one precursor is separately fired to obtain a fired body, which are then laminated. A laminate may be formed. In this case, the laminate may not be fired after pressing the laminate, or the laminate may be fired after pressing the laminate as necessary.

  In the above-described second embodiment, the case where the positive electrode precursor and the negative electrode precursor are respectively formed by the positive electrode green sheet and the negative electrode green sheet has been described as an example. However, at least one of the positive electrode precursor and the negative electrode precursor is as follows. May be formed. That is, the positive electrode slurry may be formed by applying or printing the positive electrode slurry on one surface of the solid electrolyte layer precursor or the solid electrolyte layer and then drying the positive electrode slurry. Moreover, after apply | coating or printing a negative electrode slurry to the other surface of a solid electrolyte layer precursor or a solid electrolyte layer, you may make it dry and form a negative electrode precursor.

  In the second embodiment described above, the positive electrode, the negative electrode, and the solid electrolyte layer have all been described as an example of a configuration including the sintered body of the lithium ion conductor according to the first embodiment as a solid electrolyte. The present technology is not limited to this configuration. For example, at least one of the positive electrode, the negative electrode, and the solid electrolyte layer may include a sintered body of the lithium ion conductor according to the first embodiment as a solid electrolyte. More specifically, for example, one or two of the positive electrode, the negative electrode, and the solid electrolyte layer include the sintered body of the lithium ion conductor according to the first embodiment as the solid electrolyte, and the other remaining layers. However, a lithium ion conductor other than the lithium ion conductor according to the first embodiment may be included as a solid electrolyte.

  In the second embodiment described above, the positive electrode precursor, the negative electrode precursor, and the solid electrolyte layer precursor are all described as an example including the lithium ion conductor according to the first embodiment. The technology is not limited to this configuration. For example, at least one of the positive electrode precursor, the negative electrode precursor, and the solid electrolyte layer precursor may include the lithium ion conductor according to the first embodiment. More specifically, for example, one or two of the positive electrode precursor, the negative electrode precursor, and the solid electrolyte layer precursor include the lithium ion conductor according to the first embodiment, and the other remaining layers are A lithium ion conductor other than the lithium ion conductor according to the first embodiment may be included.

The lithium ion conductor other than the lithium ion conductor according to the first embodiment is not particularly limited as long as it can conduct lithium ions, and may be either an inorganic or polymer lithium ion conductor. May be. Examples of the inorganic lithium ion conductor include Li ₂ S—P ₂ S ₅ , Li ₂ S—SiS ₂ —Li ₃ PO ₄ , Li ₇ P ₃ S ₁₁ , Li _3.25 Ge _0.25 P _0.75 S, Li _10. Sulfides such as GeP ₂ S ₁₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , Li _6.75 La ₃ Zr _1.75 Nb _0.25 O ₁₂ , Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li _{1 + x} Al _x Ti _2-x ( Examples thereof include oxides such as PO ₄ ) ₃ and La _{2 / 3-x} Li _3x TiO ₃ . Examples of the polymer lithium ion conductor include polyethylene oxide (PEO).

  In the above-described second embodiment, the case where both the positive electrode and the negative electrode are electrodes including a solid electrolyte has been described as an example. However, at least one of the positive electrode and the negative electrode may be an electrode not including a solid electrolyte. . In this case, the electrode not including the solid electrolyte may be produced by a vapor phase growth method such as a vapor deposition method or a sputtering method.

  In the second embodiment described above, the step of firing after pressing the laminated body has been described as an example, but a step of firing while pressing the laminated body may be employed.

  A stacked battery may be configured by stacking a plurality of the batteries according to the second embodiment described above.

<3 Third Embodiment>
In the third embodiment, an electronic device including the secondary battery according to the second embodiment or a modification thereof will be described.

[3.1 Configuration of electronic equipment]
Hereinafter, with reference to FIG. 3, an example of the configuration of the electronic apparatus 400 according to the third embodiment of the present technology will be described. The electronic device 400 includes an electronic circuit 401 of the electronic device body and a battery pack 300. The battery pack 300 is electrically connected to the electronic circuit 401 via the positive terminal 331a and the negative terminal 331b. For example, the electronic device 400 has a configuration in which the battery pack 300 is detachable by a user. The configuration of the electronic device 400 is not limited to this, and the battery pack 300 is built in the electronic device 400 so that the user cannot remove the battery pack 300 from the electronic device 400. May be.

  When the battery pack 300 is charged, the positive terminal 331a and the negative terminal 331b of the battery pack 300 are connected to the positive terminal and the negative terminal of a charger (not shown), respectively. On the other hand, when the battery pack 300 is discharged (when the electronic apparatus 400 is used), the positive terminal 331a and the negative terminal 331b of the battery pack 300 are connected to the positive terminal and the negative terminal of the electronic circuit 401, respectively.

  Examples of the electronic device 400 include a notebook personal computer, a tablet computer, a mobile phone (for example, a smartphone), a portable information terminal (Personal Digital Assistants: PDA), an imaging device (for example, a digital still camera, a digital video camera, etc.), Audio devices (for example, portable audio players), game devices, cordless phones, electronic books, electronic dictionaries, radios, headphones, navigation systems, memory cards, pacemakers, hearing aids, lighting devices, toys, medical devices, robots, etc. However, it is not limited to this.

(Electronic circuit)
The electronic circuit 401 includes, for example, a CPU (Central Processing Unit), a peripheral logic unit, an interface unit, a storage unit, and the like, and controls the entire electronic device 400.

(Battery pack)
The battery pack 300 includes an assembled battery 301 and a charge / discharge circuit 302. The assembled battery 301 is configured by connecting a plurality of secondary batteries 301a in series and / or in parallel. The plurality of secondary batteries 301a are connected, for example, in n parallel m series (n and m are positive integers). FIG. 3 shows an example in which six secondary batteries 301a are connected in two parallel three series (2P3S). A plurality of secondary batteries 301a may constitute a stacked secondary battery. As the secondary battery 301a, the battery according to the second embodiment or its modification is used.

  At the time of charging, the charging / discharging circuit 302 controls charging of the assembled battery 301. On the other hand, at the time of discharging (that is, when the electronic device 400 is used), the charging / discharging circuit 302 controls the discharging of the electronic device 400.

[3.2 Modification]
In the above-described third embodiment, the case where the electronic device 400 includes the assembled battery 301 including a plurality of secondary batteries 301 a has been described as an example. It is good also as a structure provided only with the secondary battery 301a.

  In the above-described third embodiment, the example in which the secondary battery according to the second embodiment or the modification thereof is applied to an electronic device has been described. However, the secondary battery according to the second embodiment or the modification thereof is It can also be applied to devices other than electronic devices. For example, electric power sources for electric vehicles (including hybrid vehicles), railway vehicles, golf carts, electric carts, road conditioners, traffic lights, etc., power supplies for auxiliary use, and power storage power sources for buildings and power generation facilities such as houses Or can be used to supply power to them. The secondary battery according to the second embodiment or its modification can also be used as a power storage device in a so-called smart grid. Such a power storage device can not only supply power but also store power by receiving power from another power source. As other power sources, for example, thermal power generation, nuclear power generation, hydroelectric power generation, solar cells, wind power generation, geothermal power generation, fuel cells (including biofuel cells) and the like can be used.

  Hereinafter, the present technology will be specifically described by way of examples. However, the present technology is not limited only to these examples.

Examples of the present technology will be described in the following order.
i Evaluation of ionic conductivity (1)
ii Evaluation of ionic conductivity (2)
iii Side reactions during firing
iv Carbon burnout during firing v Charge / discharge characteristics of all solid state battery (1)
vi Charge / Discharge Characteristics of All Solid-state Battery (2)

<Evaluation of ionic conductivity (1)>
( Reference Example 1-1)
First, Li ₂ O and GeO ₂ were mixed at a molar fraction of Li ₂ O: GeO ₂ = 23.3 mol%: 76.7 mol%, and heated and melted in the atmosphere. Next, this melt was quenched with a twin roller and then pulverized with a ball mill to obtain an amorphous Li—Ge—O-based solid electrolyte powder as a solid electrolyte. Next, the obtained Li—Ge—O-based solid electrolyte powder was pellet-molded into a disk shape having a diameter of 10 mm and a thickness of about 1 mm, and fired at 550 ° C. for 1 hour in a nitrogen atmosphere. Then, the target solid electrolyte layer was obtained by grind | polishing both surfaces of a pellet.

(Example 1-2)
A solid electrolyte layer was obtained in the same manner as in Reference Example 1-1 except that Li ₂ O and SiO ₂ were mixed at a molar fraction of Li ₂ O: SiO ₂ = 35.5 mol%: 64.5 mol%. Got.

(Example 1-3)
Li ₂ O and B ₂ O ₃ Li ₂ and in the mole fraction _{O: B 2 O 3 = 42.7mol} %: except that the mixed so that 57.3Mol% in the same manner as in Reference Example 1-1 A solid electrolyte layer was obtained.

(Example 1-4)
A solid electrolyte layer was obtained in the same manner as in Reference Example 1-1 except that Li ₂ O and P ₂ O ₅ were mixed at a molar fraction of Li ₂ O: P ₂ O ₅ = 50 mol%: 50 mol%. Got.

(Example 1-5)
A solid electrolyte layer was obtained in the same manner as in Reference Example 1-1 except that Li ₂ O and P ₂ O ₅ were mixed at a molar fraction of Li ₂ O: P ₂ O ₅ = 60 mol%: 40 mol%. Got.

(SEM observation)
Above Example 1 2 ～1-5, in the manufacturing process of the solid electrolyte layer of Example 1-1, the pellets before and after firing were SEM (Scanning Electron Microscope) observation. As a result, it was confirmed that the solid electrolyte powder was sintered at a low temperature of 550 ° C.

(Ionic conductivity)
After depositing gold (Au) as electrodes on both surfaces of the solid electrolyte layer as an evaluation sample, AC impedance measurement was performed at a temperature of 25 ° C. to create a Cole-Cole plot. FIGS. 4A and 4B show Cole-Cole plots of the solid electrolyte layers of Examples 1-2 and 1-3, respectively. Next, lithium ion conductivity was determined from this Cole-Cole plot. The results are shown in Table 1. In addition, ion conductivity was evaluated by the length of the diameter of the semicircle of the graph of the Cole-Cole plot. Solartron 1260/1287 manufactured by Solartron was used as the measuring device, and the measurement frequency was 1 MHz to 1 Hz.

From the above evaluation results, a solid electrolyte (lithium ion conductor) that can be sintered at low temperature is obtained by combining Li ₂ O with one of GeO ₂ , SiO ₂ , B ₂ O ₃ and P ₂ O _5. I understand that

<Ii Evaluation of Ionic Conductivity (2)>
(Example 2-1)
First, Li ₂ O, SiO _2, and B ₂ O ₃ are mixed at a molar fraction of Li ₂ O: SiO ₂ : B ₂ O ₃ = 70.83 mol%: 16.67 mol%: 12.5 mol%. And heated and melted in the atmosphere. Next, this melt was quenched with a twin roller and then pulverized with a ball mill to obtain amorphous Li—Si—B—O-based solid electrolyte powder as a solid electrolyte. Next, the obtained Li—Si—B—O-based solid electrolyte powder was pelletized into a disk shape having a diameter of 10 mm and a thickness of about 1 mm, and fired at 380 ° C. for 1 hour in a nitrogen atmosphere. Then, the target solid electrolyte layer was obtained by grind | polishing both surfaces of a pellet.

(SEM observation)
In the manufacturing process of the solid electrolyte layer of Example 2-1 described above, the pellets before and after firing were observed by SEM. As a result, it was confirmed that the solid electrolyte powder was sintered at a low temperature of 380 ° C.

(Ionic conductivity)
Except by alternating current impedance measurement at a temperature ranging from -30 ° C. to 80 ° C. Example 1 2 ～1-5, in the same manner as in Reference Example 1-1, a lithium ion solid electrolyte layer of Examples 2-1 The conductivity was determined. The results are shown in FIGS. 5A and 5B.

From the above evaluation results, it is understood that a solid electrolyte (lithium ion conductor) that can be sintered at low temperature can be obtained by combining Li ₂ O, SiO _2, and B ₂ O ₃ .

<Iii Side reaction during firing>
(X-ray diffraction)
In this example, a SmartLab (3 kw) manufactured by Rigaku Corporation was used for measurement of the X-ray diffraction pattern. Note that CuKα was used as the radiation source.

(Example 3-1)
First, Li ₂ O, SiO _2, and B ₂ O ₃ are mixed in a molar fraction of Li ₂ O: SiO ₂ : B ₂ O ₃ = 54 mol%: 11 mol%: 35 mol%, and Melted by heating. Next, this melt was quenched with a twin roller and then pulverized with a ball mill to obtain amorphous Li—Si—B—O-based solid electrolyte powder as a solid electrolyte. Next, the obtained Li—Si—B—O-based solid electrolyte powder was pelleted into a disk shape having a diameter of 10 mm and a thickness of about 1 mm, and fired at 430 ° C. for 1 hour in a nitrogen atmosphere. The measurement result of the X-ray diffraction pattern before and after firing the pellet is shown in FIG. 6A (before firing) and FIG. 6B (after firing). The pellets before and after firing were observed by SEM, and it was confirmed that the Li—Si—B—O-based solid electrolyte powder was sintered at the firing temperature.

  In FIG. 6A, a broad peak (halo) is observed. On the other hand, a clearer peak is observed in FIG. 6B than in FIG. 6A. From this result, it is understood that the crystallization of the solid electrolyte has progressed by sintering.

(Example 3-2)
First, LiCoO ₂ powder as a positive electrode active material was prepared. The measurement result of the X-ray diffraction pattern of this LiCoO ₂ is shown in FIG. 7A. Next, a Li—Si—B—O-based solid electrolyte powder was obtained in the same manner as in Example 3-1. Next, LiCoO ₂ powder as a positive electrode active material and Li—Si—B—O-based solid electrolyte powder were mixed to prepare a positive electrode mixture powder, and then this positive electrode mixture powder was about 10 mm in diameter and about thickness. The pellet was molded into a 1 mm disk shape and fired at 430 ° C. for 1 hour in a nitrogen atmosphere. The measurement result of the X-ray diffraction pattern after sintering the pellet is shown in FIG. 7B. The pellets before and after firing were observed by SEM, and it was confirmed that the Li—Si—B—O-based solid electrolyte powder was sintered at the firing temperature.

  The X-ray diffraction peak shown in FIG. 7B is the sum of the X-ray diffraction peaks of FIG. 6B and FIG. 7A. From this result, it is understood that when a Li—Si—B—O-based solid electrolyte powder is used as the solid electrolyte, the solid electrolyte powder can be sintered without reacting the positive electrode active material with the solid electrolyte.

(Comparative Example 3-1)
First, Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ powder was prepared as a solid electrolyte. Moreover, LiMn ₂ O ₄ powder was prepared as a positive electrode active material. Next, Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ and LiMn ₂ O ₄ are mixed to prepare a positive electrode mixture powder, and then the positive electrode mixture powder is pelletized into a disk shape having a diameter of 10 mm and a thickness of about 1 mm. Molded and fired at 830 ° C. for 2 hours in an argon atmosphere. The measurement results of the X-ray diffraction patterns before and after sintering the pellet are shown in FIG. 8A (before firing) and FIG. 8B (after firing). Note that the pellets before and after firing were observed by SEM, and it was confirmed that Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ powder was sintered at the firing temperature.

In FIG. 8A, X-ray diffraction peaks caused by Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ and LiMn ₂ O ₄ are observed. On the other hand, in FIG. 8B, an X-ray diffraction peak partially attributed to LiMn (PO 4) 3 is observed. From this result, it is understood that when Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ is used as the solid electrolyte, the solid electrolyte and the positive electrode active material are reacted in the firing step. Therefore, it can be seen that byproducts such as nonconductors are formed in the firing step, and the original characteristics of the solid electrolyte and / or the positive electrode active material may not be obtained.

<Iv Carbon burnt during firing>
(Example 4-1)
First, in the same manner as in Example 1-3, a Li—B—O-based solid electrolyte powder was obtained as a solid electrolyte. Next, this Li—B—O-based solid electrolyte powder and a carbon powder as a negative electrode active material were mixed to prepare a negative electrode mixture powder, and then this negative electrode mixture powder was 10 mm in diameter and about 1 mm in thickness. A negative electrode precursor was obtained by pellet-molding into a disk shape.

(Comparative Example 4-1)
First, Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ was prepared as a solid electrolyte. Next, this Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ and carbon powder as a negative electrode active material were mixed to prepare a negative electrode mixture powder, and then this negative electrode mixture powder was 10 mm in diameter and about 1 mm in thickness. A negative electrode precursor was obtained by pellet-molding into a disk shape.

(TGA and TMA measurement)
Thermogravimetric analysis (Thermo Gravimetry Analysis: TGA) and thermomechanical analysis (Thermomechanical Analysis: TMA) of the negative electrode precursors of Example 4-1 and Comparative Example 4-1 obtained as described above were performed in a nitrogen atmosphere. It was. The analysis results of the negative electrode precursor of Example 4-1 are shown in FIGS. 9A and 9B. Moreover, the analysis result of the negative electrode precursor of Comparative Example 4-1 is shown in FIGS. 10A and 10B. Note that the weight of the negative electrode shown on the vertical axis in FIGS. 9A and 10A represents the change in weight of the negative electrode with respect to the initial weight of the negative electrode at a temperature of 0 ° C. as a percentage. Moreover, the length of the negative electrode shown on the vertical axis in FIGS. 9B and 10B represents the amount of change in the length of the negative electrode with respect to the initial length of the negative electrode at a temperature of 0 ° C. as a percentage.

  From FIG. 9A, it can be seen that in Example 4-1, the TGA curve decreases from around 550 ° C. as the temperature rises, so that carbon begins to burn out from around 550 ° C. Further, from FIG. 9B, it can be seen that the sintering temperature is about 450 ° C. because the TMA curve rapidly decreases around 450 ° C.

  From FIG. 10A, it can be seen that in Comparative Example 3-1, the TGA curve decreases from around 700 ° C. as the temperature rises, so that carbon begins to burn out from around 700 ° C. This carbon burnout is because carbon reacts with oxygen in the atmosphere or reacts with oxygen contained in the solid electrolyte to form carbon dioxide. Further, from FIG. 10B, it can be seen that the sintering temperature is about 750 ° C. because the TMA curve rapidly decreases around 750 ° C.

From the above results, it is understood that when a Li—B—O based solid electrolyte is used as the solid electrolyte, carbon can be used as the negative electrode active material because the sintering temperature of the solid electrolyte is low. It can be seen that when Li _1.3 Al _0.3 Ti _1.7 (PO) ₃ is used as the solid electrolyte, it is difficult to use carbon as the negative electrode active material because the firing temperature of the solid electrolyte is high.

<Charge / discharge characteristics of all-solid-state battery (1)>
(Example 5-1)
[Preparation process of solid electrolyte layer precursor]
First, 90 parts by mass of a Li—Si—B—O-based solid electrolyte powder and 10 parts by mass of an acrylic resin as a binder are mixed to prepare a solid electrolyte mixture powder. The powder of the agent was dispersed in terpineol as an organic solvent to obtain a paste-like solid electrolyte slurry. Note that the same Li-Si-B-O-based solid electrolyte powder as in Example 3-1 was used.

  Next, the obtained solid electrolyte slurry was applied on a polymer resin film and dried at 100 ° C., thereby forming a green sheet on the polymer resin film. Next, the green sheet was punched into a disk shape together with the polymer film, and then the green sheet was peeled from the polymer resin film. Thereby, the solid electrolyte green sheet as a solid electrolyte layer precursor was obtained.

[Preparation process of negative electrode precursor]
First, 45 parts by mass of graphite powder as a negative electrode active material, 45 parts by mass of Li-Si-B-O-based solid electrolyte powder as a solid electrolyte, and 10 parts by mass of acrylic resin powder as a binder are mixed. After preparing the powder of the mixture, the powder of the negative electrode mixture was dispersed in terpineol as an organic solvent to obtain a paste-like negative electrode slurry. Note that the same Li-Si-B-O-based solid electrolyte powder as in Example 3-1 was used.

  Next, the obtained negative electrode slurry was applied on a polymer resin film and dried at 100 ° C., thereby forming a green sheet on the polymer resin film. Next, the green sheet was punched into a disk shape together with the polymer film, and then the green sheet was peeled from the polymer resin film. Thereby, a negative electrode green sheet as a negative electrode precursor was obtained.

[Precursor lamination and firing process]
First, a solid electrolyte green sheet and a negative electrode green sheet were laminated, and the laminate was pressed by a warm isostatic press. Next, it was baked at 430 ° C. for 1 hour in a nitrogen atmosphere. Thereby, the laminated body which consists of a solid electrolyte layer and a negative electrode was obtained. 11A and 11B show SEM images of the negative electrode green sheet before and after firing. From FIG. 11A and FIG. 11B, it can be seen that the Li—B—O-based solid electrolyte powder is sintered by low-temperature firing at 430 ° C.

  Next, a copper foil was affixed to the negative electrode side of the surface of the laminate, and a lithium metal foil was affixed to the surface of the solid electrolyte layer as a counter electrode, and then the laminate was pressurized by a hydraulic press. Thus, the intended all solid state battery (all solid state lithium ion secondary battery) was obtained.

(Charge / discharge characteristics)
The evaluation sample was charged / discharged under the following measurement conditions to obtain a charge / discharge curve. The result is shown in FIG. 11C.
Environmental temperature: 25 ° C
Charging / discharging range: 0.03V to 2.0V
Charge / discharge rate: 0.1C

  From FIG. 11C, it turns out that a high charging / discharging capacity | capacitance is obtained in the all-solid-state battery of Example 5-1.

<Charge / discharge characteristics of all-solid-state battery (2)>
(Example 6-1)
[Production process of solid electrolyte layer precursor and negative electrode precursor]
In the same manner as in Example 5-1, a solid electrolyte green sheet as a solid electrolyte layer precursor and a positive electrode green sheet as a negative electrode precursor were obtained.

[Preparation process of positive electrode precursor]
First, 45 parts by mass of LiCO ₂ powder as a positive electrode active material, 45 parts by mass of Li—Si—B—O-based solid electrolyte powder as a solid electrolyte, and 10 parts by mass of acrylic resin powder as a binder, After preparing the positive electrode mixture powder, the positive electrode mixture powder was dispersed in terpineol as an organic solvent to obtain a paste-like positive electrode slurry. Note that the same Li-Si-B-O-based solid electrolyte powder as in Example 3-1 was used.

  Next, the obtained positive electrode slurry was applied on a polymer resin film and dried at 100 ° C., thereby forming a green sheet on the polymer resin film. Next, the green sheet was punched into a disk shape together with the polymer film, and then the green sheet was peeled from the polymer resin film. Thereby, the positive electrode green sheet as a positive electrode precursor was obtained.

[Precursor lamination and firing process]
First, a positive electrode green sheet and a negative electrode green sheet were laminated so as to sandwich the solid electrolyte green sheet, and the laminate was pressed by a warm isostatic press. Next, it was baked at 430 ° C. for 1 hour in a nitrogen atmosphere. Thereby, the laminated body which consists of a positive electrode, a negative electrode, and a solid electrolyte layer was obtained. 12A and 12B show SEM images of the positive electrode green sheet before and after firing. From FIG. 12A and FIG. 12B, it can be seen that the Li—B—O-based solid electrolyte powder is sintered by low-temperature firing at 430 ° C.

  Next, while sticking copper foil on the negative electrode side surface among the surfaces of a laminated body, after sticking aluminum foil on the positive electrode side surface, the laminated body was pressurized with the hydraulic press. Thus, the intended all solid state battery (all solid state lithium ion secondary battery) was obtained.

(Charge / discharge characteristics)
The evaluation sample was charged / discharged under the following measurement conditions to obtain a charge / discharge curve. The result is shown in FIG. 12C.
Environmental temperature: 25 ° C
Charge / discharge range: 2.5V to 4.2V
Charge / discharge rate: 0.1C

  From FIG. 12C, it turns out that a favorable charging / discharging characteristic is acquired in the all-solid-state battery of Example 6-1.

  As mentioned above, although embodiment of this art, its modification, and an example were explained concretely, this art is not limited to the above-mentioned embodiment, its modification, and an example. Various modifications based on technical ideas are possible.

  For example, the configurations, methods, processes, shapes, materials, numerical values, and the like given in the above-described embodiment and its modified examples and examples are merely examples, and different configurations, methods, processes, and shapes are necessary as necessary. , Materials and numerical values may be used.

  In addition, the above-described embodiment and its modified examples, and the configurations, methods, processes, shapes, materials, numerical values, and the like of the examples can be combined with each other without departing from the gist of the present technology.

The present technology can also employ the following configurations.
(1)
One or more of GeO ₂ , SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O,
The Li ₂ O Li ion conductor content is less than 20 mol% 75 mol% of.
(2)
If the lithium ion conductor comprises the GeO _2, the content of the GeO ₂ is not more than 80 mol%,
If the lithium ion conductor including the SiO _2, the content of the SiO ₂ is less 70 mol%,
If the lithium ion conductor including the B ₂ O _3, the content of the B ₂ O ₃ is not more than 60 mol%,
If the lithium ion conductor comprises the P ₂ O _5, lithium ion conductor according to the content of the P ₂ O ₅ is not more than 50mol% (1).
(3)
The lithium ion conductor according to (1) or (2), wherein the content of Li ₂ O is more than 25 mol% and 75 mol% or less.
(4)
The lithium ion conductor according to any one of (1) to (3), wherein a sintering temperature of the lithium ion conductor is 600 ° C. or lower.
(5)
The lithium ion conductor according to any one of (1) to (3), wherein a sintering temperature of the lithium ion conductor is 300 ° C. or higher and 500 ° C. or lower.
(6)
The lithium ion conductor according to any one of (1) to (5), comprising two or more of GeO ₂ , SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O.
(7)
(1) to the lithium ion conductor according to any one of (6),
An electrode containing an active material.
(8)
The electrode according to (7), wherein the active material contains a carbon material.
(9)
The lithium ion conductor is an electrode according to (7) or (8), which is sintered.
(10)
The electrode according to any one of (7) to (9), wherein the lithium ion conductor is amorphous.
(11)
The electrode according to any one of (7) to (9), wherein the lithium ion conductor is in a mixed state of amorphous and crystalline.
(12)
A positive electrode, a negative electrode, and an electrolyte;
A battery in which at least one of the negative electrode, the positive electrode, and the electrolyte includes the lithium ion conductor according to any one of (1) to (6).
(13)
(12) including the battery according to
An electronic device that receives power from the battery.
(14)
Laminating a positive electrode precursor, a solid electrolyte precursor and a negative electrode precursor to form a laminate,
Firing the laminate at 600 ° C. or lower,
At least one of the positive electrode precursor, the solid electrolyte precursor, and the negative electrode precursor includes one or more of GeO ₂ , SiO ₂ , B ₂ O _3, and P ₂ O ₅ , and Li ₂ O;
The Li ₂ O production method of a battery content is less 20 mol% or more 75 mol% of.

11, 21, 31 Positive electrode 12, 22, 32 Negative electrode 13 Solid electrolyte layer 21A Positive electrode current collector 21B Positive electrode active material layer 22A Negative electrode current collector 22B Negative electrode active material layer 300 Battery pack 301 Battery pack 301a Secondary battery 302 Charge / discharge circuit 400 Electronic equipment 401 Electronic circuit

Claims (12)

It consists of one or more of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O,
The Li ₂ O Li ion conductor content is less than 20 mol% 75 mol% of. If the lithium ion conductor including the SiO _2, the content of the SiO ₂ is less 70 mol%,
If the lithium ion conductor including the B ₂ O _3, the content of the B ₂ O ₃ is not more than 60 mol%,
If the lithium ion conductor comprises the P ₂ O _5, Li-ion conductor according to claim 1, wherein the content of the P ₂ O ₅ is less than 50 mol%. _2. The lithium ion conductor according to claim 1, wherein the content of Li ₂ O is more than 25 mol% and 75 mol% or less. The lithium ion conductor according to claim 1, comprising at least _{two of} SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O. A lithium ion conductor according to claim 1;
An electrode containing an active material. The electrode according to claim 5 , wherein the active material contains a carbon material. The electrode according to claim 5 , wherein the lithium ion conductor is sintered. The electrode according to claim 5 , wherein the lithium ion conductor is amorphous. The electrode according to claim 5 , wherein the lithium ion conductor is in a mixed state of amorphous and crystalline. A positive electrode, a negative electrode, and an electrolyte;
The battery in which at least one of the negative electrode, the positive electrode, and the electrolyte includes the lithium ion conductor according to claim 1. A battery according to claim 10 ,
An electronic device that receives power from the battery. Laminating a positive electrode precursor, a solid electrolyte precursor and a negative electrode precursor to form a laminate,
Firing the laminate at 600 ° C. or lower,
A lithium ion conductor in which at least one of the positive electrode precursor, the solid electrolyte precursor, and the negative electrode precursor is composed of one or more of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ and Li ₂ O is used. Including
The Li ₂ O production method of a battery content is less 20 mol% or more 75 mol% of.