JP2018101466A - Battery and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium battery which is improved in reliability and charge/discharge efficiency by suppressing the occurrence of lithium segregation on a negative electrode owing to the repetition of charge and discharge operations.SOLUTION: A battery according to the present invention comprises: a negative electrode 40 including lithium; an electrolyte layer 10; and a lithium ion-conducting layer 30 including gold between the negative electrode 40 and the electrolyte layer 10.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a battery and an electronic device.

  Conventionally, an all-solid battery using a solid electrolyte instead of an organic electrolyte as an electrolyte has been known. For example, Patent Document 1 proposes an all-solid lithium battery in which a lithium ion conductive solid electrolyte containing no transition metal is interposed between a metal lithium negative electrode and a sulfide-based lithium ion conductive solid electrolyte. ing.

JP 2004-206942 A

  However, the all-solid-state lithium battery described in Patent Literature 1 has a problem that local precipitation of lithium metal (segregation of lithium) easily occurs in the negative electrode by repeating charge and discharge. Specifically, in a solid electrolyte having high lithium ion conductivity, there is a path through which lithium ions easily move, and it has been difficult to improve the uniformity of lithium ion conductivity. Therefore, by repeating charge and discharge, the movement of lithium ions tends to be biased in the path, and lithium segregation is likely to occur. When segregation of lithium occurs, physical stress is generated at the interface between the negative electrode and the solid electrolyte, which may cause problems such as peeling and destruction. Moreover, segregation of lithium occurred through repeated charge and discharge, and irregularities were generated at the interface, resulting in a decrease in charge and discharge efficiency.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example] A battery according to this application example includes an electrode including lithium, an electrolyte layer, and a lithium ion conductive layer including gold between the electrode and the electrolyte layer.

  According to this application example, even when charging and discharging are repeated, generation of lithium segregation in the electrode (negative electrode) can be suppressed. Specifically, since the lithium ion conductive layer contains gold, the lithium ion conductivity is lowered, but there are many places where the conductivity is high or low by inserting a lithium ion conductive layer (composite layer). From a relatively non-uniform state, it becomes a relatively uniform state with some conductivity. Therefore, by providing a lithium ion conductive layer having uniform conductivity between the electrode and the electrolyte layer, the movement path of lithium ions is less likely to be biased during charging and discharging, and the occurrence of segregation of lithium can be suppressed. Accordingly, it is possible to reduce the occurrence of peeling or destruction at the interface between the electrode (negative electrode) and the electrolyte layer due to the segregation of lithium, thereby improving the reliability and providing a battery with improved charge / discharge efficiency. be able to.

  In the battery described in the above application example, the electrolyte layer is preferably a composite including an active material and an electrolyte.

  According to this, compared with the case where the active material and the electrolyte are laminated as layers, the contact area between the active material and the electrolyte is increased, the internal resistance is reduced, and the lithium ion conductivity is improved.

  In the battery according to the application example described above, the electrolyte preferably includes a crystalline first electrolyte and a second electrolyte that cover the surface of the active material.

  According to this, lithium ion conductivity can be further improved by using a crystalline first electrolyte in the electrolyte layer. Therefore, a battery having excellent charge / discharge characteristics can be provided.

In the battery according to the application example described above, the second electrolyte preferably includes a compound represented by the following formula (1).
Li _{2 + x} C _1-x B _x O ₃ (1)
However, 0.01 <x <0.5 is satisfied.

  According to this, generation of dendrites due to lithium segregation is suppressed, and an electrolyte layer having a dense structure is formed. Therefore, lithium ion conductivity can be further improved. In addition, for example, it is less susceptible to moisture than a solid electrolyte such as SiO, and long-term stability can be improved.

  The battery described in the application example preferably includes an alloy containing lithium, gold, and oxygen between the lithium ion conductive layer and the electrode.

  According to this, the homogeneity of lithium movement is further improved by the alloy containing lithium, gold, and oxygen. Therefore, the occurrence of segregation of lithium in the electrode (negative electrode) can be further suppressed, and unevenness derived from the segregation of lithium can be further prevented from occurring in the electrode.

  [Application Example] An electronic apparatus according to this application example includes the battery described in the above application example.

  According to this application example, it is possible to provide an electronic device including a battery in which generation of lithium segregation is suppressed and reliability and charge / discharge efficiency are improved as a power supply source.

1 is a schematic perspective view showing a configuration of a lithium battery as a battery according to Embodiment 1. FIG. The schematic sectional drawing which shows the structure of a lithium battery. The process flowchart which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. The graph which shows the evaluation result of the lithium battery which concerns on an Example and a comparative example. The graph which shows the charging / discharging efficiency of a lithium battery. FIG. 5 is a schematic cross-sectional view showing a structure of a lithium battery as a battery according to Embodiment 3. The process flowchart which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. The schematic diagram which shows the manufacturing method of a lithium battery. Schematic which shows the structure of the wearable apparatus which concerns on Embodiment 4. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is made different from the actual scale so that each layer and each member can be recognized.

(Embodiment 1)
<Battery>
First, the battery according to the present embodiment will be described with reference to FIG. In the present embodiment, a lithium battery will be described as an example of the battery. FIG. 1 is a schematic perspective view showing a configuration of a lithium battery as a battery according to Embodiment 1. FIG.

  As shown in FIG. 1, the lithium battery 100 of this embodiment includes a negative electrode 40 as an electrode containing lithium, an electrolyte layer 10, and a lithium ion conductive layer 30 containing gold between the negative electrode 40 and the electrolyte layer 10. It is equipped with. The electrolyte layer 10 is a composite that includes the active material 2 b and the electrolyte 3. The active material 2 b and the electrolyte 3 form a positive electrode 9 in the electrolyte layer 10. In addition, the electrolyte layer 10 includes a separator layer 20. The separator layer 20 is provided between the positive electrode 9 and the lithium ion conductive layer 30.

  A first current collector 41 is provided in contact with one surface 10 a of the electrolyte layer 10. That is, the lithium battery 100 is a laminated body in which the first current collector 41, the positive electrode 9, the separator layer 20, the lithium ion conductive layer 30, and the negative electrode 40 are laminated in order. In the positive electrode 9, the surface in contact with the separator layer 20 is defined as one surface 9 a. In the separator layer 20, a surface facing the surface 9 a of the positive electrode 9 and in contact with the lithium ion conductive layer 30 is defined as a surface 20 a. The surface in contact with the negative electrode 40 in the lithium ion conductive layer 30 is defined as one surface 30a. Note that a second current collector (not shown) may be provided as appropriate to the lithium ion conductive layer 30 through the negative electrode 40, and the lithium battery 100 is in contact with at least one of the positive electrode 9 and the negative electrode 40. What is necessary is just to have an electric body. Here, the “layer” in this specification refers to a material in which a material such as an active material or an electrolyte is formed with a certain thickness.

  The first current collector 41 and the second current collector are preferably used as long as they are formation materials that do not cause an electrochemical reaction with the electrolyte layer 10 and the negative electrode 40 and have electron conductivity. it can. As a material for forming the first current collector 41 and the second current collector, for example, copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), One metal selected from the group consisting of zinc (Zn), aluminum (Al), germanium (Ge), indium (In), gold (Au), platinum (Pt), silver (Ag), and palladium (Pd) (Metal alone), alloys containing at least one metal element selected from the above group, ITO (Tin-doped Indium Oxide), ATO (Antimony-doped Tin Oxide), FTO (Fluorine-doped Tin Oxide), etc. And metal nitrides such as titanium nitride (TiN), zirconium nitride (ZrN), and tantalum nitride (TaN).

  The forms of the first current collector 41 and the second current collector are not only a thin film of the above-mentioned forming material having electron conductivity, but also a metal foil, a plate, a paste obtained by kneading fine conductor powder together with a binder, etc. Appropriate ones can be selected according to. The first current collector 41 and the second current collector may be formed after the electrolyte layer 10, the negative electrode 40, or the like is formed, or before they are formed.

Examples of the negative electrode active material (formation material) included in the negative electrode 40 include niobium pentoxide (Nb ₂ O ₅ ), vanadium pentoxide (V ₂ O ₅ ), titanium oxide (TiO ₂ ), and indium oxide (In ₂ O _3). ), Zinc oxide (ZnO), tin oxide (SnO ₂ ), nickel oxide (NiO), indium oxide (ITO) to which tin (Sn) is added, zinc oxide (AZO) to which Al is added, gallium (Ga) Added zinc oxide (GZO), antimony (Sb) added tin oxide (ATO), fluorine (F) added tin oxide (FTO), TiO ₂ anatase phase, Li ₄ Ti ₅ O ₁₂ , lithium composite oxide such as Li ₂ Ti ₃ O _7, lithium (Li), silicon (Si), Sn, silicon - manganese alloy (Si-Mn), silicon - cobalt alloy (Si-Co), silicon - two Kell alloy (Si-Ni), In, metals and alloys, such as Au, a carbon material, lithium ions, and the like inserted material between layers of the carbon material.

  The thickness of the negative electrode 40 is preferably about 50 nm to about 100 μm, but can be arbitrarily designed according to desired battery capacity and material characteristics.

  The lithium battery 100 has a disk shape, for example, and has an outer size of about 10 mm in diameter and a thickness of about 150 μm. In addition to being small and thin, charging and discharging are possible and a large output energy can be obtained, so that it can be suitably used as a power supply source (power source) for a portable information terminal or the like. The shape of the lithium battery 100 is not limited to a disk shape, and may be a polygonal disk shape, for example. Such a thin lithium battery 100 may be used alone, or a plurality of lithium batteries 100 may be stacked. In the case of stacking, in the lithium battery 100, the first current collector 41 and the second current collector are not necessarily indispensable configurations, and may be configured to include one current collector.

  Next, the structure of the electrolyte layer 10 and the lithium ion conductive layer 30 included in the lithium battery 100 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing the structure of the lithium battery.

<Electrolyte layer>
As described above, the electrolyte layer 10 includes the positive electrode 9 and the separator layer 20. The positive electrode 9 includes an active material 2 b and an electrolyte 3. The active material 2b is in the form of particles, and a plurality of active material 2b particles gather to form the active material part 2.

[Active material part]
The active material part 2 is an aggregate of the particulate active material 2b and has a plurality of holes. The plurality of holes communicate with each other in a mesh shape inside the active material portion 2. Therefore, the contact between the active materials 2b is ensured. The electrolyte 3 is provided so as to fill a plurality of holes in the active material portion 2 and further cover the entire active material portion 2. That is, the active material portion 2 and the electrolyte 3 are composited to form a composite (positive electrode 9). Therefore, compared with the case where the active material part 2 does not have a plurality of holes or the case where the electrolyte 3 is not provided up to the holes, the contact area between the active material 2b and the electrolyte 3 is increased. As a result, the interface resistance is reduced, and good charge transfer is possible at the interface between the active material portion 2 and the electrolyte 3.

  As in the lithium battery 100 of the present embodiment, when the first current collector 41 is used on the positive electrode side, a commonly known lithium composite metal compound is used as a material for forming the active material 2b (positive electrode active material). Can be used. FIG. 2 schematically shows the active material 2b, and the actual particle size and size are not necessarily the same.

  The lithium composite metal compound used for the positive electrode active material refers to a compound that contains lithium and that contains two or more metal elements as a whole, and in which the presence of oxo acid ions is not recognized. .

Examples of the lithium composite metal compound include a composite metal compound containing Li and containing at least one element selected from vanadium (V), chromium (Cr), manganese (Mn), Fe, Co, Ni, and Cu. It is done. Such composite metal compound is not particularly limited, _{specifically, LiCoO 2, LiNiO 2, LiMn} 2 O 4, Li 2 Mn 2 O 3, LiCr 0.5 Mn 0.5 O 2, LiFePO 4, Li 2 FeP _{2 O 7, LiMnPO 4, LiFeBO} 3, Li 3 V 2 (PO 4) 3, Li 2 CuO 2, LiFeF 3, Li 2 FeSiO 4, Li 2 MnSiO 4, NMC (Li a (Ni x Mn y Co 1- _{xy) O 2), NCA (} Li (Ni x Co y Al 1-xy) O 2) , and the like. In this embodiment, a solid solution in which some atoms in the crystals of these lithium composite metal compounds are substituted with other transition metals, typical metals, alkali metals, alkali rare earths, lanthanoids, chalcogenides, halogens, etc. is also lithium. These solid solutions can be used as a positive electrode active material.

  By using a lithium composite metal compound as the active material 2b as the material for forming the active material part 2, electrons are transferred between the particles of the active material 2b, and lithium ions are transferred between the active material 2b and the electrolyte 3. Is done. Thereby, the function as the active material part 2 (electrolyte layer 10) can be exhibited satisfactorily.

  The active material part 2 preferably has a bulk density of 50% or more and 90% or less, and more preferably 50% or more and 70% or less. When the active material part 2 has such a bulk density, the surface area in the pores of the active material part 2 is expanded, and the contact area between the active material part 2 and the electrolyte 3 is easily increased. As a result, the capacity of the lithium battery 100 can be increased more easily than in the past.

When the above bulk density is β (%), the apparent volume including the pores of the active material part 2 is v, the mass of the active material part 2 is w, and the density of the particles of the active material 2b is ρ, the following formula (x ) Holds. Thereby, a bulk density can be calculated | required.
β = {w / (v · ρ)} × 100 (x)

  In order to set the bulk density of the active material portion 2 in the above range, the average particle diameter (median diameter) of the active material 2b is preferably set to 0.3 μm or more and 10 μm or less. More preferably, it is 0.5 μm or more and 5 μm or less. The average particle diameter of the active material 2b is, for example, that the active material 2b is dispersed in n-octyl alcohol so as to have a concentration in the range of 0.1% by mass or more and 10% by mass or less. It can be measured by determining the median diameter using a truck UPA-EX250 (Nikkiso Co., Ltd.).

  The bulk density of the active material part 2 can also be controlled by using a pore expanding material in the step of forming the active material part 2.

  The resistivity of the active material part 2 is preferably 700 Ωcm or less. Since the active material part 2 has such a resistivity, a sufficient output can be obtained in the lithium battery 100. The resistivity can be obtained by attaching a copper foil as an electrode to the surface of the active material portion 2 and performing DC polarization measurement.

In the active material part 2, since the plurality of holes communicate with each other in a network shape, the solid part of the active material part 2 also forms a network structure. For example, LiCoO ₂ that is a positive electrode active material is known to have anisotropy in the electronic conductivity of crystals. Therefore, in a configuration in which the holes extend in a specific direction, such as the holes formed by machining, the electron conductivity may be lowered depending on the direction of electron conductivity in the crystal. . In contrast, in the present embodiment, since the active material portion 2 has a network structure, an electrochemically active continuous surface is formed regardless of the anisotropy of the electron conductivity or ion conductivity of the crystal. Can do. Therefore, good electron conduction can be ensured regardless of the type of forming material used.

  In the active material part 2, it is preferable to reduce the amount of the binder (binder) that joins the active materials 2 b and the pore former for adjusting the bulk density of the active material part 2 as much as possible. . If the binder and pore former remain in the active material part 2 (electrolyte layer 10), the electrical characteristics may be adversely affected. Therefore, it is necessary to carefully remove the post-process and remove it. Specifically, in the present embodiment, the mass reduction rate when the electrolyte layer 10 is heated at 400 ° C. for 30 minutes is set to 5 mass% or less. The mass reduction rate is more preferably 3% by mass or less, still more preferably 1% by mass or less, and more preferably no mass reduction is observed or within a measurement error range. When the electrolyte layer 10 has such a mass reduction rate, the amount of a solvent to be evaporated, adsorbed water, an organic substance that is burned or oxidized and vaporized under a predetermined heating condition is reduced. Thereby, the electrical characteristics (charge / discharge characteristics) of the lithium battery 100 can be further improved.

[Electrolytes]
The electrolyte 3 includes a crystalline first electrolyte 3a and a second electrolyte 3c that cover the surface of the active material 2b (active material portion 2). In other words, the electrolyte 3 includes the coating 3b of the first electrolyte 3a formed on the surface including the inside of the hole of the active material portion 2, and the second electrolyte 3c. The coating 3b is provided on the surface including the inside of the hole of the active material part 2, and is interposed between the active material part 2 (active material 2b) and the second electrolyte 3c. That is, the coating 3 b is provided on the surface of the active material portion 2, and the second electrolyte 3 c is provided on the surface of the coating 3 b including the inside of the hole of the active material portion 2, thereby forming the electrolyte 3.

As a material for forming the first electrolyte 3a and the second electrolyte 3c (solid electrolyte), for _{example, SiO 2 -P 2 O 5 -Li} 2 O, SiO 2 -P 2 O 5 -LiCl, Li 2 O-LiCl-B ₂ O ₃ , Li _3.4 V _0.6 Si _0.4 O ₄ , Li ₁₄ ZnGe ₄ O ₁₆ , Li _3.6 V _0.4 Ge _0.6 O ₄ , Li _1.3 Ti _1.7 Al _0.3 (PO ₄ ) ₃ , Li _2.88 PO _3.73 N _0.14 , LiNbO ₃ Li _0.35 La _0.55 TiO ₃ , Li ₇ La ₃ Zr ₂ O ₁₂ , Li _6.75 La ₃ Zr _1.75 Nb _0.25 O ₁₂ , Li ₂ S—SiS ₂ , Li ₂ S—SiS ₂ —LiI, Li ₂ S—P _{2 S 5, Li 2 S-SiS} 2 -P 2 S 5, LiPON, LiI, LiI-CaI 2, LiI-CaO, LiAlCl 4, LiAlF 4, LiI-Al 2 O 3, LiF-Al 2 O 3, LiBr- Al ₂ O ₃ , Li ₂ O—TiO ₂ , La ₂ O ₃ —Li ₂ O—TiO ₂ , Li ₃ N, Li ₃ NI ₂ , Li ₃ N—LiI—LiOH, Li ₃ N—LiCl, Li ₆ NBr ₃ , LiSO ₄ , Li ₄ SiO ₄ , Li _{3 PO 4 -Li 4 SiO 4, Li} 4 GeO 4 -Li 3 VO 4, Li 4 SiO 4 -Li 3 VO 4, Li 4 GeO 4 -Zn 2 GeO 2, Li 4 SiO 4 -LiMoO 4, LiSiO 4 -Li ₄ ZrO ₄ , Li _B H ₄ , Li _7-x PS _6-x Cl _x , Li ₁₀ GeP ₂ S ₁₂ , Li ₂ CO ₃ , Li ₃ BO ₃ , Li _{2 + x} C _1-x B _x O ₃ , Li _{1 + x + y} Al _x (Ti, Ge) _2−x Si _y P _3−y O ₁₂ and other oxides, sulfides, halides, nitrides, hydrides, or partially substituted crystals thereof, Examples thereof include amorphous and partially crystallized glass. Further, solid solutions in which some atoms of these compounds are substituted with other transition metals, typical metals, alkali metals, alkali rare earths, lanthanoids, chalcogenides, halogens, or the like may be used.

Here, it is preferable that the forming material (solid electrolyte) of the second electrolyte 3c includes a compound represented by the following formula (1) among the solid electrolytes described above.
Li _{2 + x} C _1-x B _x O ₃ (1)
However, 0.01 <x <0.5 is satisfied.

Specific examples of the compound satisfying the formula (1) include Li _2.2 C _0.8 B _0.2 O ₃ . By using the above-described forming material for the second electrolyte 3c, dendrites due to lithium segregation are suppressed and a complex structure (positive electrode 9) is formed. Thereby, lithium ion conductivity can be further improved. In addition, it can be made less susceptible to moisture than a SiO-based solid electrolyte, and long-term stability can be improved.

Further, the forming material (solid electrolyte) of the first electrolyte 3a is preferably crystalline. Although it does not specifically limit as a crystalline solid electrolyte, For example, the lithium complex metal compound containing the lanthanum and zirconium represented by following formula (2) is mentioned.
Li _7-x La ₃ (Zr _2-x , M _x ) O ₁₂ (2)
M is at least one of Nb (niobium), Sc (scandium), Ti, V, Y (yttrium), Hf (hafnium), Ta (tantalum), Al, Si, Ga, Ge, Sn, and Sb. Represents a seed, and x represents a real number of 0 or more and less than 2.

M in Formula (2) is more preferably at least one of Nb, Ta, and Sb. Examples of such a solid electrolyte include Li _6.75 La ₃ (Zr _1.75 , Nb _0.25 ) O ₁₂ . The lithium ion conductivity of the electrolyte layer 10 can be further improved by using the above-described forming material for the first electrolyte 3a (coating 3b).

  Here, if a crystalline solid electrolyte is used as a material for forming the coating 3b (first electrolyte 3a) and the composite (positive electrode 9) of the active material portion 2, the coating 3b, and the second electrolyte 3c is formed, the electrolyte layer 10 is formed. The lithium ion conductivity can be further improved.

  As an index of lithium ion conductivity of the solid electrolyte used for the electrolyte 3, ion conductivity can be employed. The ionic conductivity of the solid electrolyte is the bulk conductivity as the conductivity of the solid electrolyte itself, the grain boundary conductivity as the conductivity between the particles of the crystal when the solid electrolyte is crystalline, The total ionic conductivity, which is the sum of In addition, the index of grain boundary resistance in the solid electrolyte is grain boundary conductivity. If the grain boundary conductivity increases, the grain boundary resistance is reduced.

The total ionic conductivity of the solid electrolyte is preferably 5.0 × 10 ⁻⁵ S (Siemens) / cm or more. When the solid electrolyte has such total ionic conductivity, it becomes easy for lithium ions contained in the electrolyte 3 at a position away from the surface of the active material part 2 to reach the surface of the active material part 2. Thereby, the lithium ions can also contribute to the battery reaction in the active material part 2, and the capacity of the lithium battery 100 can be increased.

  The total ionic conductivity of the solid electrolyte can be measured using a tablet prepared from the solid electrolyte powder. Specifically, the solid electrolyte powder is formed into a tablet shape at 624 MPa and sintered at 700 ° C. for 8 hours in an air atmosphere. Next, a platinum electrode having a diameter of 0.5 cm and a thickness of 100 nm is formed by sputtering to obtain a tablet for measurement. The total ionic conductivity can be obtained by the AC impedance method using this tablet. For example, an impedance analyzer SI1260 (Solartron) can be used as the measuring device.

  In the present embodiment, two types of solid electrolytes of the first electrolyte 3a and the second electrolyte 3c are used as the electrolyte 3, and the coating 3b is formed on the surface of the active material portion 2, but the present invention is not limited to this. For example, the electrolyte 3 may be formed by using the second electrolyte 3c alone without forming the coating 3b of the first electrolyte 3a on the surface of the active material portion 2.

[Separator layer]
As described above, the separator layer 20 is provided between the positive electrode 9 and the lithium ion conductive layer 30. The separator layer 20 includes the second electrolyte 3c and does not include the first electrolyte 3a and the active material 2b. Since the separator layer 20 that does not include the active material 2b is interposed between the positive electrode 9 and the negative electrode 40, the positive electrode 9 and the negative electrode 40 are not easily electrically connected, and the occurrence of a short circuit is suppressed. The separator layer 20 is preferably in an amorphous state having no interface having lithium ion conductivity.

  The thickness of the separator layer 20 is preferably 0.1 μm or more and 100 μm or less, and more preferably 0.2 μm or more and 10 μm or less. By setting the thickness of the separator layer 20 within the above range, the internal resistance of the separator layer 20 can be reduced, and the occurrence of a short circuit between the positive electrode 9 and the negative electrode 40 can be suppressed.

  In addition, an uneven structure such as a trench, a grating, or a pillar may be provided on one surface 20a of the separator layer 20 (a surface in contact with the lithium ion conductive layer 30) by combining various molding methods and processing methods as necessary.

<Lithium ion conductive layer>
As described above, the lithium ion conductive layer 30 contains gold and is provided between the negative electrode 40 and the electrolyte layer 10 (separator layer 20). Gold has low lithium ion conductivity compared to a solid electrolyte, but has excellent lithium ion conductivity homogeneity. Therefore, the lithium ion conductive layer 30 containing gold has a function of alleviating unevenness of lithium ion conduction (movement). Since the lithium battery 100 includes the lithium ion conductive layer 30 between the negative electrode 40 and the electrolyte layer 10, the movement path of lithium ions is less likely to be biased during charge and discharge. Therefore, even if charging / discharging is repeated, generation | occurrence | production of lithium segregation can be suppressed.

  The thickness of the lithium ion conductive layer 30 is not less than 50 nm and not more than 100 nm. When the thickness of the lithium ion conductive layer 30 is in the above range, generation of lithium segregation can be suppressed and the internal resistance in the lithium ion conductive layer 30 can be reduced.

  An alloy containing lithium, gold, and oxygen is generated between the lithium ion conductive layer 30 and the negative electrode 40, that is, at the interface (one surface 30 a) where the lithium ion conductive layer 30 contacts the negative electrode 40. Similar to the lithium ion conductive layer 30, the alloy has a function of mitigating the deviation of the lithium ion movement path during charging and discharging. Therefore, the occurrence of lithium segregation can be further suppressed.

  Here, as a material for forming the lithium ion conductive layer 30, in addition to gold, a metal that forms an alloy with lithium may be used. The metal that forms an alloy with lithium is not particularly limited as long as it has lithium ion conductivity, does not significantly impair lithium ion conductivity, and does not produce a by-product due to charging / discharging of the lithium battery 100. Further, an organic material may be used as long as it does not lose lithium ion conductivity by reacting with lithium.

<First current collector>
One surface 10a of the electrolyte layer 10 is in contact with the first current collector 41 as described above. Since the active material portion 2 is exposed on the one surface 10a, the active material portion 2 and the first current collector 41 are provided in contact with each other, and both are electrically connected. The electrolyte 3 is provided up to the hole of the active material part 2 and is in contact with the surface of the active material part 2 other than the part in contact with the first current collector 41. In the electrolyte layer 10 having such a configuration, the contact area between the active material part 2 and the electrolyte 3 is larger than the contact area between the first current collector 41 and the active material part 2. As a result, the interface between the active material portion 2 and the electrolyte 3 is unlikely to become a bottleneck for charge transfer, and therefore, it is easy to ensure good charge transfer as the electrolyte layer 10. Is possible.

<Battery manufacturing method>
A method for manufacturing the lithium battery 100 of the present embodiment will be described with reference to FIGS. 3, 4A, 4B, 4C, 4D, 4E, and 4F. FIG. 3 is a process flow diagram illustrating a method for manufacturing a lithium battery. 4A to 4F are schematic views showing a method for manufacturing a lithium battery. In addition, the process flow shown in FIG. 3 is an example, Comprising: It is not limited to this.

  As shown in FIG. 3, the manufacturing method of the lithium battery 100 includes steps S1 to S10 described below.

In step S1, a porous molded body including the active material 2b is formed. In the present embodiment, the above-described lithium composite metal compound LiCoO ₂ is used as a material for forming the active material 2b. First, LiCoO ₂ (Sigma Aldrich) particles are classified in n-butanol using a wet centrifuge LC-1000 type (Krettek) to obtain an active material 2b having an average particle diameter of about 5 μm. . As a result of measuring the melting point of the active material 2b using a thermogravimetric / calorimeter simultaneous measurement apparatus STA8000 (Perkin Elmer), it was approximately 1130 ° C.

Next, the active material 2b is compression molded using the molding die 81. Specifically, as shown in FIG. 4A, the active material 2b is pressurized for 2 minutes at a pressure of 50 MPa using a molding die 81 (a die with an exhaust port having an inner diameter of 10 mm). At this time, the active material 2b may be mixed with a binder or a pore former to perform compression molding. However, it is preferable to use a binder and a pore former that are easily decomposed or volatilized in the subsequent baking. Thereby, a disk-shaped porous compact (diameter 10 mm, effective diameter 8 mm, thickness 150 μm) is obtained from LiCoO ₂ (active material 2b).

  In step S2, the molded body is fired to form the active material portion 2. As shown in FIG. 4B, the molded body of the active material 2b is placed on the substrate 82, and subjected to a heat treatment at 900 ° C. for 8 hours to obtain the active material portion 2. The temperature of heat processing is 850 degreeC or more, for example, Comprising: Temperature below melting | fusing point of the active material 2b is preferable. The particles of the active material 2b are sintered by this heat treatment, and the shape of the molded body is easily maintained. In addition, the active materials 2b come into contact with each other and are combined to form an electron movement path.

  Thereby, the active material 2b is sintered together, and the integrated active material part 2 is obtained. By setting the temperature of the heat treatment to 850 ° C. or higher, sintering proceeds sufficiently and electron conductivity in the crystal of the active material 2b is ensured. By setting the temperature of the heat treatment to be lower than the melting point of the active material 2b, lithium ions in the crystal of the active material 2b are prevented from excessively volatilizing, and lithium ion conductivity is maintained. Thereby, it is possible to ensure the electric capacity of the electrolyte layer 10. The temperature of the heat treatment is more preferably 875 ° C. or higher and 1000 ° C. or lower. Thereby, in the lithium battery 100 using the electrolyte layer 10, an appropriate output and capacity can be provided.

  The heat treatment time is preferably, for example, 5 minutes or longer and 36 hours or shorter. More preferably, it is 4 hours or more and 14 hours or less. The active material part 2 which has a some hole is obtained by the above process.

  A material for forming the substrate 82 on which the molded body is placed is not particularly limited, but it is preferable to use a material that hardly reacts with the active material 2b, the first electrolyte 3a, and the second electrolyte 3c.

In step S3, a solution 3bX containing a precursor of the first electrolyte 3a (hereinafter, also simply referred to as “precursor solution 3bX”) is prepared. In the present embodiment, Li _6.75 La ₃ (Zr _1.75 , Nb _0.25 ) O ₁₂ (hereinafter also referred to as “LLZNb”) is used as the first electrolyte 3 a.

  Specifically, for example, a toluene / propionic acid solution of lithium acetate at a concentration of 1.0 mol / kg, 10.125 g, a toluene / 2-butoxyethanol solution of lanthanum 2-ethylhexanoate at a concentration of 0.4 mol / kg, 5.250 g. , 3.719 g of propionic acid solution of zirconium acrylate at a concentration of 0.4 mol / kg and 0.250 g of 2-butoxyethanol solution of niobium pentaethoxide at a concentration of 1.0 mol / kg were weighed on a 90 ° C. hot plate. Mix by heating for 30 minutes. Thereafter, it is gradually cooled to room temperature to obtain an LLZNb precursor solution (precursor solution 3bX).

  Here, in the LLZNb precursor solution, lithium may be volatilized and reduced by heating or baking in a subsequent process. Therefore, taking into account the reduced amount of lithium, a lithium source (toluene / propionic acid solution of lithium acetate at a concentration of 1 mol / kg) so that the molar ratio is 1.2 times the original theoretical composition of LLZNb. May be blended.

In addition, as a precursor solution containing solid electrolyte like LLZNb, at least 1 sort (s) of the following (a), (b), (c), (d) can be used. Among these, (b) is a precursor for forming a solid electrolyte by using a sol-gel method. In the present embodiment, the following composition (d) is used.
(A) A composition containing a metal atom contained in a solid electrolyte in a proportion according to the composition formula of the solid electrolyte and having a salt that becomes a solid electrolyte by oxidation.
(B) The composition which has a metal alkoxide compound which contains the metal atom which a solid electrolyte has in the ratio according to the composition formula of a solid electrolyte.
(C) A dispersion in which fine particles of a solid electrolyte or fine particle sol containing metal atoms of the solid electrolyte in a proportion according to the composition formula of the solid electrolyte are dispersed in a solvent.
(D) A composition comprising a metal atom contained in a solid electrolyte in a proportion according to the composition formula of the solid electrolyte, and a salt that becomes a solid electrolyte by oxidation and a metal alkoxide compound.

  In step S4, the precursor solution 3bX and the active material part 2 are brought into contact with each other, and the precursor solution 3bX is applied to the surface of the active material part 2. Specifically, as shown in FIG. 4C, the precursor solution 3bX is applied to the surface including the inside of the hole of the active material portion 2 using the dispenser 83 on the substrate 82.

  As a method of applying the precursor solution 3bX, in addition to the dropping by the dispenser 83, for example, means such as dipping, spraying, penetration by capillary action, spin coating, etc. can be used. Good. Since the precursor solution 3bX has fluidity, it can easily reach the pores of the active material portion 2. At this time, the precursor solution 3bX is applied so as to spread over the entire surface including the inside of the pores of the active material portion 2.

  In step S5, the first electrolyte 3a is deposited on the surface including the inside of the pores of the active material portion 2 to form a coating 3b of the first electrolyte 3a. First, the precursor solution 3bX applied to the active material part 2 is dried. As a drying method, at least one of commonly known methods such as heating, decompression, and air blowing can be employed.

  Next, the active material part 2 to which the precursor solution 3bX has been applied and dried is heated at a first temperature. The first temperature is preferably 500 ° C. or higher and 900 ° C. or lower. By setting the first temperature to 500 ° C. or higher at which organic substances can be removed, organic substances as components, impurities, and contaminants contained in the active material part 2 (active material 2b) and the precursor solution 3bX are reduced by thermal decomposition. Is done. In addition, by setting the upper limit of the heating temperature to 900 ° C. or less, the solid electrolyte is prevented from being deteriorated and the generation of impurities is suppressed. The first temperature is more preferably 510 ° C. or higher and 880 ° C. or lower, and further preferably 520 ° C. or higher and 860 ° C. or lower. In the present embodiment, the first temperature is 540 ° C. By heating at a temperature in the above range, generation of impurities can be suppressed and thermal decomposition of organic matter can be promoted. The heating time at the first temperature is not particularly limited, and can be, for example, 0.5 hours or more and 24 hours or less.

  The heating at the first temperature is performed under the condition where dry air containing carbon dioxide is pressurized to atmospheric pressure or higher. At this time, the concentration of carbon dioxide is preferably 200 ppm or more. More preferably, it is 300 ppm or more, More preferably, it is 400 ppm. Moreover, it is preferable that the density | concentration of the water | moisture content contained as dry air shall be 130 ppm or less. In the dry air, the oxygen concentration is preferably 1000 ppm or less, more preferably 130 ppm or less. By setting the atmosphere during heating to the above-described conditions, precipitation of LLZNb (first electrolyte 3a) can be promoted, and generation of impurities such as lithium carbonate can be suppressed.

  The operations from the step S4 to the heating at the first temperature in the step S5 are repeatedly performed until the bulk density of the active material part 2 and the precipitated LLZNb is about 50%. By repeating the application and heating of the precursor solution 3bX, a dense LLZNb coating 3b can be formed on the surface including the inside of the active material portion 2.

  Separately, the precursor solution 3bX was heated at 900 ° C. in pressurized dry air for 8 hours to produce a solid material of LLZNb, and the melting point was measured in the same manner as the active material 2b. As a result, it was about 1100 ° C.

  Next, as shown in FIG. 4D, heating is performed on the substrate 82 at a second temperature higher than the first temperature described above. The second temperature is preferably 700 ° C. or higher and 950 ° C. or lower. More preferably, they are 720 degreeC or more and 930 degrees C or less, More preferably, they are 740 degreeC or more and 910 degrees C or less. In the present embodiment, the second temperature is 800 ° C. Thereby, baking of the active material part 2 and the film 3b advances, and electrical characteristics, such as lithium ion conductivity, are ensured.

  The heating at the second temperature is preferably performed in the same atmosphere as the heating at the first temperature. Note that the partial pressure of carbon dioxide is lower than that under atmospheric pressure in accordance with the second temperature. Therefore, it is preferable to adjust the concentration of carbon dioxide corresponding to the second temperature. A preferable carbon dioxide concentration is 400 ppm or more when the second temperature is 700 ° C., 300 ppm or more when the second temperature is 800 ° C., and 200 ppm or more when the second temperature is 900 ° C.

  By adjusting the atmosphere in the heating at the second temperature, the remaining organic substances and generated impurities can be reduced as in the heating at the first temperature. Furthermore, it is preferable to adjust the oxygen concentration in the dry air as in the case of heating at the first temperature. A preferable oxygen concentration is 1000 ppm or less, and more preferably 130 ppm or less. The heating time at the second temperature is not particularly limited, and can be, for example, 1 hour or more and 36 hours or less. In the present embodiment, the heating time at the second temperature is 8 hours.

In step S6, the molded pellet 5 is formed using the particulate second electrolyte 3c. In the present embodiment, Li _2.2 C _0.8 B _0.2 O ₃ (hereinafter also referred to as “LCBO”) is used as the second electrolyte 3c. First, LCBO particles (powder) are prepared. Specifically, for example, Li ₂ CO ₃ and Li ₃ BO ₃ are mixed at a mass mixing ratio of 4: 1, and a molding die 81 is used for 2 minutes at a pressure of 30 MPa to obtain a tablet shape. Then, it puts into a high temperature furnace and bakes at 650 degreeC for 4 hours, and produces the solid substance of LCBO. The solid is pulverized using a dry mill or the like to obtain LCBO particles (particles of the second electrolyte 3c) as a powder. Here, the melting point of the produced LCBO particles was approximately 685 ° C. as a result of measurement in the same manner as in the active material 2b. In addition, the manufacturing method of the particulate 2nd electrolyte 3c is not limited to the method mentioned above, A well-known method is employable.

  Next, compression molding is performed on the particulate second electrolyte 3 c to form a molded pellet 5. Using the mold 81, the particulate second electrolyte 3c is pressurized at a pressure of 30 MPa for 2 minutes. Thereby, the shaping | molding pellet 5 is obtained from the particulate 2nd electrolyte 3c.

  In step S7, the active material portion 2 and the molded pellet 5 are heated while being in contact with each other, and the second electrolyte 3c is melted and cooled, thereby including the active material 2b, the first electrolyte 3a, and the second electrolyte 3c. A positive electrode 9 is formed. First, as shown in FIG. 4E, the molded pellet 5 is placed on the upper surface (ceiling surface) of the active material portion 2 placed on the substrate 82. The mass of the molded pellet 5 is preferably set to a mass that is sufficient to fill the hole in the active material portion 2 on which the coating 3b is formed. In this state, the entire system including the molded pellet 5 alone or the molded pellet 5, the active material part 2, and the substrate 82 is heated.

  The heating temperature at this time is set to be equal to or higher than the melting point of the second electrolyte 3c (LCBO). By this heating, the second electrolyte 3c is melted to become a melt (liquid) and spreads on the surface including the inside of the hole of the active material portion 2 on which the coating 3b is formed. Thereby, the melt (liquid material) of the second electrolyte 3 c is applied to the inside of the hole of the active material portion 2.

  The heating temperature is not limited to the above numerical value as long as it is higher than the melting point of the second electrolyte 3c and lower than the melting point of the first electrolyte 3a, and can be arbitrarily set. In this embodiment, the heating temperature is 700 ° C.

  The above heating operation is preferably performed under dry air having a moisture concentration of 130 ppm or less. By performing in such an atmosphere, generation | occurrence | production of impurities etc. can be suppressed. Furthermore, the carbon dioxide concentration in the dry air is preferably 400 ppm or more. By adjusting the carbon dioxide concentration, thermal decomposition of the electrolyte 3 (particularly, the second electrolyte 3c containing carbon) can be suppressed. In addition, it replaces with the shaping | molding pellet 5, and may place the powdery 2nd electrolyte 3c in the active material part 2, and may perform the said operation. Laser annealing may be used as a heating means for the molded pellets 5.

  Next, the active material part 2 coated with the liquid material is cooled. As a cooling condition, a gradual cooling method using natural cooling is used. When using a method of forcibly releasing heat, it is necessary to suppress the thermal shock while paying attention to the cooling rate. In any case, the atmosphere during cooling is preferably dry air having a moisture concentration of 130 ppm or less, as in the heating operation in step S7.

  The liquid is solidified by cooling. At this time, the second electrolyte 3c is solidified in contact with the coating 3b (first electrolyte 3a) provided on the surface of the active material portion 2, and the electrolyte 3 including the first electrolyte 3a and the second electrolyte 3c is formed. Is done. Thereby, the positive electrode 9 in which the active material portion 2 and the electrolyte 3 are combined is formed.

  Here, by adjusting the mass of the molded pellet 5 placed on the active material portion 2, the separator layer 20 containing the second electrolyte 3c is placed on the ceiling surface on which the molded pellet 5 of the active material portion 2 is placed. 9 can be formed simultaneously. Alternatively, the separator layer 20 containing LCBO may be formed on one surface of the positive electrode 9 using a known method such as a sputtering method. In this embodiment, amorphous LCBO is formed using a sputtering method. At this time, the thickness of the separator layer 20 to be formed is about several μm. Thereby, the electrolyte layer 10 having the positive electrode 9 and the separator layer 20 is formed.

  In step S <b> 8, the lithium ion conductive layer 30 is formed on the one surface 20 a of the separator layer 20. For the formation of the lithium ion conductive layer 30, a known method such as a sputtering method or a vapor deposition method can be employed. In this embodiment, gold is used as a forming material, and the lithium ion conductive layer 30 is formed by a sputtering method so as to have a thickness of 50 nm.

  In step S <b> 9, the negative electrode 40 is formed on the one surface 30 a of the lithium ion conductive layer 30. The formation method of the negative electrode 40 includes CVD (Chemical) using an appropriate metal compound and a gas atmosphere in addition to a so-called sol-gel method involving a hydrolysis reaction of an organometallic compound and a solution process such as an organometallic thermal decomposition method. Vapor Deposition (ALD) method, ALD (Atomic Layer Deposition) method, Green Sheet method and screen printing method using slurry of solid electrolyte particles, Aerosol deposition method, Sputtering method using appropriate target and gas atmosphere, PLD (Pulsed Laser) Deposition) method, vacuum deposition method, plating, thermal spraying, etc. can be used. Further, the negative electrode active material described above can be employed as a material for forming the negative electrode 40. In the present embodiment, a negative electrode 40 is formed by depositing lithium (Li metal) having a thickness of about 3 μm using a vacuum deposition method.

  In step S <b> 10, the first current collector 41 is formed on the one surface 10 a of the electrolyte layer 10 so as to be in contact with the electrolyte layer 10. First, as shown in FIG. 4F, the surface of the electrolyte layer 10 that faces the surface on which the separator layer 20 is formed is polished in an atmosphere of an inert gas such as Ar (argon). At this time, the active material portion 2 is reliably exposed by polishing to form the one surface 10a. Thereby, the active material 2b is electrically connected to the first current collector 41. In the above-described process, when the active material portion 2 is sufficiently exposed on the facing surface, polishing may be omitted and the facing surface may be the one surface 10a.

  The polishing method is not particularly limited. For example, for polishing, a lapping film sheet # 15000 (manufactured by 3M, abrasive grain size: 0.3 μm) is used as an abrasive to perform mechanical polishing to form one surface 10a.

  Next, the first current collector 41 is formed (formed) on the one surface 10a. As a method of forming the first current collector 41, a method of separately providing an appropriate adhesive layer and bonding, a PVD (Physical Vapor Deposition) method, a CVD method, a PLD method, an ALD method and an aerosol deposition method, an appropriate target and Reactivity with the formation surface, electrical conductivity desired for electrical circuits, electricity, etc., such as gas phase deposition methods such as sputtering using gas atmosphere, sol-gel methods, organometallic pyrolysis methods and wet methods such as plating An appropriate method can be used depending on the circuit design. In addition, as the forming material of the first current collector 41, the above-described forming materials can be employed. In the present embodiment, the first current collector 41 is formed by depositing gold using a sputtering method. The lithium battery 100 is manufactured through the above steps.

  As described above, according to the lithium battery 100 according to the embodiment, the following effects can be obtained.

  According to the embodiment described above, in the lithium battery 100, even when charging / discharging is repeated, occurrence of lithium segregation in the negative electrode 40 can be suppressed. Specifically, since the lithium ion conductive layer 30 contains gold, the homogeneity of lithium ion conductivity is improved. Gold has low lithium ion conductivity compared to a solid electrolyte, but is excellent in lithium ion conductivity homogeneity. Therefore, the lithium ion conductive layer 30 has a function of alleviating the unevenness of lithium ion conduction (movement). Providing the lithium ion conductive layer 30 between the negative electrode 40 and the electrolyte layer 10 makes it difficult for the migration path of lithium ions to be biased during charge and discharge, thereby suppressing the occurrence of segregation of lithium. Therefore, it is possible to provide the lithium battery 100 in which the occurrence of peeling or breakage at the interface between the negative electrode 40 and the electrolyte layer 10 is reduced, reliability is improved, and charge / discharge efficiency is also improved.

  Since the lithium battery 100 includes an alloy containing lithium, gold, and oxygen between the lithium ion conductive layer 30 and the negative electrode 40, the generation of lithium segregation in the negative electrode 40 can be further suppressed by the alloy.

  By forming a composite of the active material 2b and the electrolyte 3, the contact area between the active material 2b and the electrolyte 3 is increased and the internal resistance is reduced as compared with the case where each is laminated as a layer. Improves.

  Since the coating 3b is formed using crystalline LLZNb as the first electrolyte 3a and LCBO is used as the second electrolyte 3c, lithium ion conductivity can be further improved.

  Next, an example and a comparative example are shown about the lithium battery 100 of the said embodiment, and the effect of the said embodiment is demonstrated more concretely. The weighing in the following experiment was performed using an analytical balance ME204T (Mettler Toledo).

<Manufacture of lithium batteries>
Example 1
The lithium battery of Example 1 was manufactured using the manufacturing method and forming material of Embodiment 1 described above.

(Comparative Example 1)
The lithium battery of Comparative Example 1 was omitted without forming the lithium ion conductive layer 30 of the lithium battery of Example 1. That is, the lithium battery of Comparative Example 1 does not have the lithium ion conductive layer 30, and the negative electrode 40 is formed in contact with the one surface 20a of the separator layer 20. Otherwise, the lithium battery of Comparative Example 1 was produced in the same manner as in Example 1.

<Evaluation of lithium battery>
[Charge / discharge cycle test]
As an evaluation of the lithium batteries of Example 1 and Comparative Example 1, a charge / discharge cycle test was performed, and the results are shown in FIGS. FIG. 5 is a chart showing evaluation results of lithium batteries according to examples and comparative examples. FIG. 6 is a graph showing the charge / discharge efficiency of the lithium battery.

  First, before the charge / discharge cycle test, the battery was charged to 30 μAh with a charge current of 1 μA, and then discharged to a lower limit voltage of 2.8 V with a discharge current of 1 μA. The above operation was performed once to conduct lithium ions.

  Next, the battery was charged to 100 μAh with a charging current of 5 μA, then discharged to a lower limit voltage of 2.8 V with a discharge current of 5 μA, and the discharge capacity was measured. The charging / discharging operation described above was performed as one cycle and repeated up to 5 cycles. The charge / discharge efficiency value was calculated by dividing the charge / discharge capacity value by the measured discharge capacity value. The charge / discharge efficiency in 1 cycle, 3 cycles, and 5 cycles is shown in FIG. In addition, a graph was created with the horizontal axis representing the number of charge / discharge cycles and the vertical axis representing the charge / discharge efficiency, which are shown in FIG.

[Section observation]
About the lithium battery of Example 1 and Comparative Example 1, after performing the said charging / discharging cycle test, cross-sectional observation of the lithium battery was performed. Specifically, FIB (Focused Ion Beam) cross-section processing was performed using a FIB-SEM composite apparatus NX9000 (Hitachi High-Tech Inologies). Thereafter, using the same apparatus, for Example 1, the interface between the negative electrode 40 (Li) and the lithium ion conductive layer 30 (Au) (negative electrode interface), the interface between the separator layer 20 and the electrolyte layer 10 (one surface 9a). The cross section was observed. For Comparative Example 1, the cross section of the interface (negative electrode interface) between the negative electrode 40 and the separator layer 20 and the entire surface 9a was observed. The results of cross-sectional observation were evaluated according to the following criteria, and the evaluation results are shown in FIG.
A: Li segregation is not observed at the negative electrode interface, and no breakage is observed at the negative electrode interface and one surface 9a.
B: Li segregation is observed at the negative electrode interface, but no breakage is observed on the negative electrode interface and one surface 9a.
C: Li segregation is observed at the negative electrode interface, and fractures are observed on the negative electrode interface or one surface 9a.

D: Li segregation is observed at the negative electrode interface, and fractures are observed at the negative electrode interface and one surface 9a.

<Evaluation results>
As shown in FIGS. 5 and 6, the lithium battery of Example 1 has a charge / discharge efficiency of 50% or more in 5 cycles of charge / discharge, and no segregation or breakage of lithium was observed. Note that. The cross section of the negative electrode interface was subjected to elemental analysis by EDX (Energy Dispersive X-ray spectroscopy), and as a result, formation of an alloy of lithium, gold, and oxygen was recognized at the interface between the lithium ion conductive layer 30 and the negative electrode 40. Thereby, between the separator layer 20 and the negative electrode 40, the homogeneity of lithium ion conductivity was further improved, and the occurrence of segregation of lithium due to charge / discharge was suppressed. That is, it was shown that the lithium battery of Example 1 is not easily affected by charging / discharging, and the charging / discharging efficiency and reliability are improved as compared with the prior art.

  On the other hand, in Comparative Example 1, the charge / discharge efficiency in 5 cycles of charge / discharge was significantly lower than 30%, and segregation of lithium at the negative electrode interface and fracture at the negative electrode interface or one surface 9a were observed. Therefore, it was found that the lithium battery of Comparative Example 1 was inferior in charge / discharge efficiency and reliability as compared with the lithium battery of Example 1.

(Embodiment 2)
<Battery>
A lithium battery will be described as an example of the battery according to this embodiment. In addition, about the component same as Embodiment 1, the same number is used and the overlapping description is abbreviate | omitted.

The lithium battery of the present embodiment is different from the lithium battery 100 of the first embodiment in that Li _{1 + x + y} Al _x (Ti, Ge) _2−x Si _y P _3−y O ₁₂ (hereinafter, Also referred to as “LATP”). The positive electrode of LATP can be formed using a known manufacturing method. Other than this, the lithium ion conductive layer 30 and the lithium battery 100 have the same configuration.

  According to the present embodiment, as in the first embodiment, it is possible to provide a lithium battery in which generation of lithium segregation is suppressed and charge / discharge efficiency and reliability are improved.

(Embodiment 3)
<Battery>
The battery according to the present embodiment will be described with reference to FIG. 7 taking a lithium battery as an example of the battery. FIG. 7 is a schematic cross-sectional view showing the structure of a lithium battery as a battery according to Embodiment 3. In addition, about the component same as Embodiment 1, the same number is used and the overlapping description is abbreviate | omitted.

  As shown in FIG. 7, the lithium battery 200 of the present embodiment has the same configuration as the lithium battery 100 except that the electrolyte layer 10 of the lithium battery 100 of the first embodiment is replaced with the electrolyte layer 11.

  The electrolyte layer 11 includes a positive electrode 19 as a composite including the active material 12b and the electrolyte 13, and a separator layer 20 including the second electrolyte 3c. In the positive electrode 19, the particulate active material 12 b forms an aggregate to form the active material portion 12. As the active material 12b and the electrolyte 13, the above-described forming materials can be used.

<Battery manufacturing method>
A method for manufacturing the lithium battery 200 of the present embodiment will be described with reference to FIGS. 8, 9A, and 9B. FIG. 8 is a process flow diagram illustrating a method for manufacturing a lithium battery. 9A and 9B are schematic views showing a method for manufacturing a lithium battery. In addition, the process flow shown in FIG. 8 is an example, Comprising: It is not limited to this.

  As shown in FIG. 8, the manufacturing method of the lithium battery 200 includes steps S11 to S17 described below and employs a so-called green sheet method.

In step S11, in order to form the positive electrode 19 included in the electrolyte layer 11, a slurry 19X including the active material 12b, the formation material of the electrolyte 13, and the like is prepared. In the present embodiment, NMC is used as the material for forming the active material 12b, and Li ₂ S—P ₂ S ₅ is used as the material for forming the electrolyte 13. The active material 12b and the electrolyte 13 are preferably used in the form of particles (powder) in order to improve the dispersibility in the slurry 19X. These may be commercially available in powder form, or manufactured after being produced by a known method and processed into powder form. You may add a dispersing agent, an antifoamer, a pore making material, etc. to the slurry 19X as an auxiliary agent.

  The solvent contained in the slurry 19X is not particularly limited as long as it does not have chemical reactivity with the active material 12b and the electrolyte 13. Examples of such a solvent include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, allyl alcohol, ethylene glycol monobutyl ether (2-n-butoxyethanol), and ethylene. Glycols such as glycol, propylene glycol, butylene glycol, hexylene glycol, pentanediol, hexanediol, heptanediol, dipropylene glycol, ketones such as dimethyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl formate, formic acid Esters such as ethyl, methyl acetate, methyl acetoacetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether Diethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, ethers such as 1,4-dioxane and tetrahydrofuran (THF), organic acids such as formic acid, acetic acid, 2-ethylbutyric acid and propionic acid And organic solvents such as aromatics such as toluene, o-xylene and p-xylene, and amides such as formamide, N, N-dimethylformamide, N, N-diethylformamide, dimethylacetamide and N-methylpyrrolidone. . In this embodiment, 1,4-dioxane (Kanto Chemical Co., Inc.) is used as the solvent.

Into a glass beaker, 20 g of 1,4-dioxane, 2 g of powdered NMC and 1 g of Li ₂ S—P ₂ S _5, and a magnetic stirrer are placed and mixed while stirring with a magnetic stirrer. Thereby, slurry 19X in which NMC and Li ₂ S—P ₂ S ₅ are dispersed in 1,4-dioxane is prepared.

  In step S12, a sheet-like molded product 19Y is formed from the slurry 19X. As shown in FIG. 9A, the slurry 19X is coated on a base material 85 using a coating machine 84 such as a bar coater to form a sheet-like molded product 19Y. At this time, the composition of the slurry 19X can be appropriately changed in accordance with the desired thickness of the molded product 19Y, the performance of the coating machine 84, and the like.

  In the present embodiment, a fully automatic film applicator (Cotec) is used as the coating machine 84, and coating is performed on a base material 85 made of polyethylene terephthalate to form a sheet-like molded product 19Y from the slurry 19X. The thickness of the molded product 19Y is about 150 μm.

  In step S13, the positive electrode 19 is formed from the molded product 19Y. First, as shown in FIG. 9B, the molded product 19Y is subjected to heat treatment. The conditions for the heat treatment are not particularly limited. For example, the molded product 19Y is heated at 100 ° C. or higher and 350 ° C. or lower for 2 to 8 hours to remove organic substances such as a solvent. From the state of FIG. 9B, the solvent is volatilized and decomposed and eliminated. Then, heat treatment (baking) is performed at 800 ° C. or higher and 1000 ° C. or lower for 4 to 18 hours using an electric muffle furnace or the like.

  By this firing, the active material 12b is not melted and the particles are sintered to form the electrically connected active material portion 12. In addition, the particles of the electrolyte 13 are melted to form a melt, spread on the surface including the inside of the pores of the active material portion 12, and include the entire active material portion 12. By cooling from this state, a complex in which the electrolyte 13 and the active material part 12 are complexed is formed. Thereafter, the composite is cut into a disk shape having a diameter of 10 mm, for example, and used as the positive electrode 19.

  In step S <b> 14, the separator layer 20 is formed on one surface of the positive electrode 19. The forming material and forming method of the separator layer 20 are the same as those in the first embodiment. In addition, since subsequent process S15 to process S17 are the same as that of process S8 to process S10 among the manufacturing methods of the lithium battery 100 in Embodiment 1, description is abbreviate | omitted.

  According to the present embodiment, as in the first embodiment, it is possible to provide the lithium battery 200 in which the occurrence of segregation of lithium is suppressed and the charge / discharge efficiency and reliability are improved. In addition, since the green sheet method is employed, processes such as the formation of the active material portion 2 in Embodiment 1 can be omitted, and the manufacturing process of the lithium battery 200 can be simplified.

(Embodiment 4)
<Electronic equipment>
An electronic apparatus according to the present embodiment will be described with reference to FIG. In the present embodiment, a wearable device will be described as an example of an electronic device. FIG. 10 is a schematic diagram illustrating a configuration of a wearable device as an electronic device according to the fourth embodiment.

  As shown in FIG. 10, the wearable device 400 according to the present embodiment is an information device that uses a band 310 to be worn like a wristwatch on a human body, for example, a wrist WR, and obtain information related to the human body. The wearable device 400 includes a battery 305, a display unit 325, a sensor 321, and a processing unit 330. As the battery 305, the lithium battery of the above embodiment is used.

  The band 310 has a band shape using a resin having flexibility such as rubber so as to be in close contact with the wrist WR when worn. At the end of the band 310, a coupling portion (not shown) whose coupling position can be adjusted corresponding to the thickness of the wrist WR is provided.

  The sensor 321 is disposed on the inner surface side (the wrist WR side) of the band 310 so as to touch the wrist WR when worn in the band 310. The sensor 321 obtains information related to the pulse and blood sugar level of the human body by touching the wrist WR, and outputs the information to the processing unit 330. As the sensor 321, for example, an optical sensor is used.

  The processing unit 330 is built in the band 310 and is electrically connected to the sensor 321 and the display unit 325. For example, an integrated circuit (IC) is used as the processing unit 330. Based on the output from the sensor 321, the processing unit 330 performs arithmetic processing such as a pulse and a blood glucose level, and outputs display data to the display unit 325.

  The display unit 325 displays display data such as a pulse and a blood glucose level output from the processing unit 330. As the display unit 325, for example, a light receiving type liquid crystal display device is used. The display unit 325 is arranged on the outer surface side of the band 310 (side facing the inner surface on which the sensor 321 is arranged) so that the wearer can read display data when the wearable device 400 is worn.

  The battery 305 functions as a power supply source that supplies power to the display unit 325, the sensor 321, and the processing unit 330. The battery 305 is built in the band 310 in a detachable state.

  With the above configuration, the wearable device 400 can obtain information on the wearer's pulse and blood sugar level from the wrist WR, and can display the information as information on the pulse and blood sugar level through arithmetic processing. In addition, since the wearable device 400 uses the lithium battery according to the above-described embodiment in which the occurrence of segregation of lithium is suppressed, reliability and charge / discharge efficiency can be improved as compared with the related art. Furthermore, since the lithium battery of the above embodiment is an all-solid-type secondary battery, it can be used repeatedly by charging, and there is no risk of leakage of electrolyte etc. It is possible to provide a wearable device 400 that can be used.

  In the present embodiment, a wristwatch-type wearable device is illustrated as the wearable device 400, but the present invention is not limited to this. For example, the wearable device may be worn on the ankle, head, ear, waist, or the like.

  Further, the electronic device to which the battery 305 (the lithium battery of the above embodiment) as a power supply source is applied is not limited to the wearable device 400. Other electronic devices include, for example, a head-mounted display such as a head-mounted display, a head-up display, a mobile phone, a portable information terminal, a laptop computer, a digital camera, a video camera, a music player, wireless headphones, and a portable game machine. Etc. These electronic devices may have other functions such as a data communication function, a game function, a recording / playback function, and a dictionary function, for example.

  Moreover, the electronic device of this embodiment is not limited to the use for general consumers, but can also be applied to industrial use. Furthermore, a device to which the lithium battery of the above embodiment is applied is not limited to an electronic device. For example, you may apply the lithium battery of the said embodiment as an electric power supply source of a moving body. Specific examples of the moving body include a flying body such as an automobile, a motorcycle, a forklift, and an unmanned airplane. According to this, the mobile body provided with the battery with improved reliability and charging / discharging efficiency as a power supply source can be provided.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below.

(Modification 1)
In the said embodiment, although formed so that the thickness of the lithium ion conductive layer 30 might be set to about 50 nm, the structure of the lithium ion conductive layer 30 is not limited to this. For example, the lithium ion conductive layer may be formed in a mesh shape having a thickness of several μm. According to this, an alloy containing lithium, gold, and oxygen is formed between the lithium ion conductive layer and the negative electrode 40 after the first charge / discharge. Therefore, generation of lithium segregation in the negative electrode 40 can be suppressed.

  DESCRIPTION OF SYMBOLS 2,12 ... Active material part, 2b, 12b ... Active material, 3, 13 ... Electrolyte, 3a ... 1st electrolyte, 3c ... 2nd electrolyte, 9, 19 ... Positive electrode, 10, 11 ... Electrolyte layer, 30 ... Lithium ion Conductive layer, 40 ... negative electrode as electrode containing lithium, 20 ... separator layer, 41 ... first current collector, 100, 200 ... lithium battery as battery, 305 ... battery, 400 ... wearable device as electronic device.

Claims (6)

An electrode containing lithium;
An electrolyte layer;
A battery comprising a lithium ion conductive layer containing gold between the electrode and the electrolyte layer.   The battery according to claim 1, wherein the electrolyte layer is a composite including an active material and an electrolyte.   The battery according to claim 1, wherein the electrolyte includes a crystalline first electrolyte and a second electrolyte that cover a surface of the active material. The battery according to claim 1, wherein the second electrolyte includes a compound represented by the following formula (1).
Li _{2 + x} C _1-x B _x O ₃ (1)
However, 0.01 <x <0.5 is satisfied.   5. The battery according to claim 1, comprising an alloy containing lithium, gold, and oxygen between the lithium ion conductive layer and the electrode.   The electronic device provided with the battery of any one of Claims 1-5.

Images