JP2017054761A - Method for inspecting all-solid lithium battery, and method for manufacturing all-solid lithium battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a method for inspecting an all-solid lithium battery, by which the presence or absence of short circuit and fine short circuit can be determined in a simple and convenient manner; and a method for manufacturing an all-solid lithium battery.SOLUTION: A method for inspecting an all-solid lithium battery comprises the step of making determination on the presence or absence of short circuit and fine short circuit in a unit battery 1 having an oriented positive electrode plate 12, a solid electrolyte layer 14, an intermediate layer 15 including a metal alloyable with lithium and formed by a sputtering method, and a negative electrode layer 16 including lithium, by comparing an open end voltage of the unit battery 1 with a predetermined threshold.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an inspection method for an all-solid lithium battery and a method for manufacturing an all-solid lithium battery.

  Conventionally, an inspection method for a short circuit or a short circuit in an all-solid lithium battery including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer has been proposed.

  In Patent Document 1, the presence or absence of a short circuit is determined based on whether or not the current value when a constant current is supplied to an all-solid lithium battery is normal.

  In Patent Document 2, when the amount of voltage drop due to self-discharge in the initial charge state exceeds a reference value, whether or not the amount of voltage drop due to self-discharge under a pressure exceeding the constraint pressure during actual use exceeds the reference value. The presence or absence of a slight short circuit is determined.

  Note that the fine short circuit is a phenomenon in which the terminal voltage gradually decreases in a no-discharge state due to a slight self-discharge compared to the short circuit.

JP 2012-138299 A Japanese Patent Laying-Open No. 2015-122169

  However, in the method of Patent Document 1, it is difficult to accurately detect whether or not the current value is normal, and therefore it is not possible to accurately determine the presence or absence of a fine short circuit.

  Moreover, although the method of patent document 2 can discriminate | determine the presence or absence of a fine short circuit, there exists a problem that an inspection process is complicated and requires a long time.

  The present invention has been made in view of the above-described situation, and an object thereof is to provide an inspection method for an all-solid lithium battery and a method for manufacturing an all-solid lithium battery that can easily determine the presence or absence of a short circuit and a micro short circuit. To do.

  An inspection method for an all-solid lithium battery according to the present invention includes: a positive electrode layer; a solid electrolyte layer formed on the positive electrode layer; an intermediate layer containing a metal that is formed on the solid electrolyte layer by a sputtering method and can be alloyed with lithium; And comparing the open circuit voltage of the unit cell formed on the intermediate layer and having a negative electrode layer containing lithium with a predetermined threshold value to determine whether the unit cell is short-circuited or slightly short-circuited.

  ADVANTAGE OF THE INVENTION According to this invention, the inspection method of the all-solid-state lithium battery which can distinguish the presence or absence of a short circuit and a fine short circuit easily, and the manufacturing method of an all-solid-state lithium battery can be provided.

Sectional drawing of the all-solid-state lithium battery which concerns on embodiment Top view of an all-solid-state lithium battery according to an embodiment The flowchart which shows the inspection method of the all-solid-state lithium battery which concerns on embodiment Sample No. according to the example. Scatter chart showing the relationship between open-circuit voltage and self-discharge rate for 1 to 15 Sample No. according to the example. Scatter chart showing the relationship between open-circuit voltage and self-discharge rate for 16-30

(Overall configuration of all-solid lithium battery 10)
FIG. 1 is a cross-sectional view of an all solid lithium battery 10 according to the present embodiment. FIG. 2 is a top view of the all-solid lithium battery 10.

  The all-solid-state lithium battery 10 is used as a power source for various devices including personal computers and portable devices (for example, mobile phones). The all solid lithium battery 10 is mounted on a substrate of various devices through a heating process (for example, a process involving a temperature of 200 ° C. or higher) such as a reflow soldering process.

  The all solid lithium battery 10 includes two unit batteries 1. The unit battery 1 includes an oriented positive electrode plate 12 (an example of a positive electrode layer), a solid electrolyte layer 14, an intermediate layer 15, and a negative electrode layer 16. The two unit batteries 1 are connected in parallel.

  The all solid lithium battery 10 includes an exterior portion 2. The exterior portion 2 includes two positive electrode exterior materials 20, one negative electrode exterior material 24, and two sealing portions 26. The exterior part 2 covers the two unit batteries 1. The two unit cells 1 are arranged symmetrically with respect to the negative electrode exterior material 24.

  The all solid lithium battery 10 includes two connecting portions 3. The connecting portion 3 is constituted by the metal layer 22, the conductive adhesive layer 28, and the end insulating portion 18. The connection part 3 fixes the unit battery 1 to the exterior part 2.

(Configuration of unit battery 1)
The unit battery 1 includes an oriented positive electrode plate 12, a solid electrolyte layer 14, an intermediate layer 15, and a negative electrode layer 16.

1. Oriented positive electrode plate 12
The oriented positive electrode plate 12 is a plate-like ceramic sintered body. Therefore, since the thickness of the alignment positive electrode plate 12 can be easily increased, the capacity and energy density of the battery can be increased as compared with a film formed by a vapor phase method. Further, since the composition of the aligned positive electrode plate 12 is determined by the weighing of the raw materials, the composition can be controlled with higher accuracy than a film formed by a vapor phase method. The thickness of the alignment positive electrode plate 12 is not particularly limited, but is preferably 5 μm or more and 80 μm or less, and more preferably 20 μm or more and 50 μm or less.

  The oriented positive electrode plate 12 is an oriented polycrystal composed of a plurality of oriented lithium transition metal oxide particles. That is, the particles forming the aligned positive electrode plate 12 which is an oriented polycrystal are composed of a lithium transition metal oxide.

The lithium transition metal oxide preferably has a layered rock salt structure or a spinel structure, and more preferably has a layered rock salt structure. The layered rock salt structure has the property that the redox potential decreases due to the accumulation of lithium ions, and the redox potential increases due to the release of lithium ions. Here, the layered rock salt structure is a crystal structure in which transition metal layers other than lithium and lithium layers are alternately stacked via layers containing oxygen atoms. That is, the layered rock salt structure is a crystal structure in which an ion layer of a transition metal other than lithium and a lithium ion layer are alternately stacked with an oxide ion layer interposed therebetween. Examples of such a crystal structure include an α-NaFeO ₂ type structure in which transition metals and lithium are regularly arranged in the [111] axis direction of a cubic rock salt type structure.

  Examples of lithium-transition metal composite oxides having a layered rock salt structure include lithium cobaltate, lithium nickelate, lithium manganate, nickel / lithium manganate, nickel / lithium cobaltate, cobalt / nickel / lithium manganate, cobalt / Examples thereof include lithium manganate. Lithium-transition metal composite oxides include Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Ag, Sn, and Sb. , Te, Ba, Bi, etc. may contain one or more elements.

Thus, the lithium transition metal oxide particles are Li _x M1O ₂ or Li _x (M1, M2) O ₂ (where 0.5 <x <1.10, M1 is from the group of Ni, Mn and Co). At least one selected transition metal element, M2 is Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Ag, Sn, It is preferable to have a composition represented by (at least one element selected from the group consisting of Sb, Te, Ba and Bi). The lithium transition metal oxide particles have a composition represented by Li _x (M1, M2) O ₂ , M1 is Ni and Co, and M2 is selected from the group of Mg, Al, and Zr More preferably, it is at least one. More preferably, the lithium transition metal oxide particles have a composition represented by Li _x (M1, M2) O ₂ , M1 is Ni and Co, and M2 is Al. Furthermore, it is also preferable that the lithium transition metal oxide particles have a composition represented by Li _x M1O ₂ and M1 is Ni, Mn and Co, or M1 is Co.

Note that the composition formula Li _x (M1, M2) O ₂ is specifically Li _x (M1 _m , M2 _n ) ( _where 0 <m <1, 0 <n <1, m + n = 1). It is expressed. In the formula, the proportion of Ni in the total amount of M1 and M2 is preferably 0.6 or more in terms of atomic ratio. All of the above compositions can take a layered rock salt structure.

A ceramic having a Li _x (Ni, Co, Al) O ₂ -based composition, M1 being Ni and Co, and M2 being Al is referred to as NCA ceramic. NCA ceramics have the general formula Li _p (Ni _x , Co _y , Al _z ) O ₂ (where 0.9 ≦ p ≦ 1.3, 0.6 <x ≦ 0.9, 0.1 <y ≦ 0.3, 0 ≦ z ≦ 0.2, x + y + z = 1), and preferably has a layered rock salt structure.

  As described above, the oriented positive electrode plate 12 is an oriented polycrystal composed of a plurality of oriented lithium transition metal oxide particles. In the aligned positive electrode plate 12, the plurality of lithium transition metal oxide particles are preferably aligned in a predetermined direction. The predetermined direction is preferably a lithium ion conduction direction. Therefore, the specific crystal planes of the constituent particles of the oriented positive electrode plate 12 are preferably oriented in the direction from the oriented positive electrode plate 12 toward the negative electrode layer 16. Specifically, the (003) plane of the constituent particles of the oriented positive electrode plate 12 is preferably oriented in the stacking direction of the oriented positive electrode plate 12, the solid electrolyte layer 14, the intermediate layer 15, and the negative electrode layer 16. In other words, it is preferable that the (003) plane is oriented in a direction crossing the laminated surface. As a result, the resistance at the time of accumulation and release of lithium ions with respect to the alignment positive electrode plate 12 can be reduced, so that a large amount of lithium ions can be released at the time of high input (that is, during charging) and at the time of high output (that is, during discharge). ) Can accumulate a lot of lithium ions.

  The degree of orientation of the oriented polycrystal can be 10% or more. The lower limit of the degree of orientation of the oriented polycrystal is preferably 20% or more, more preferably 30% or more, further preferably 40% or more, and particularly preferably 50% or more. The upper limit of the degree of orientation is not particularly limited, but can be 95% or less. The upper limit of the degree of orientation can be 90% or less, 85% or less, 80% or less, 75% or less, or 70% or less. The orientation degree of the orientation positive electrode plate 12 is calculated from the following formula (1) according to the Lotgering method using an XRD profile on the contact surface 12S obtained by an XRD apparatus (for example, TTR-III manufactured by Rigaku Corporation). The measurement by the XRD apparatus is performed under the condition of 2 ° / min and a step width of 0.02 ° in an X-ray diffraction angle range of 2 ° to 10 ° to 70 °.

上記式（１）において、Ｉは、測定試料の回折強度であり、Ｉ_０は無配向の参照試料の回折強度である。（ＨＫＬ）は、配向度を評価したい回折線であり、（００ｌ）（ｌは、例えば３、６及び９）以外の回折線に相当にする。（ｈｋｌ）は、全ての回折線に相当する。

In the above formula (1), I is the diffraction intensity of the measurement sample, and I ₀ is the diffraction intensity of the non-oriented reference sample. (HKL) is a diffraction line for which the degree of orientation is to be evaluated, and corresponds to diffraction lines other than (00l) (l is, for example, 3, 6 and 9). (Hkl) corresponds to all diffraction lines.

  The non-oriented reference sample is a sample having the same configuration as the positioning sample except that it is non-oriented. The reference sample is obtained, for example, by pulverizing a sample of the aligned positive electrode plate 12 with a mortar to make it non-oriented.

  In the above formula (1), the (001) diffraction line is removed from (HKL) in the plane corresponding to the (001) diffraction line (for example, the (003) plane) in the in-plane direction. This is because, since lithium ions can only move, if this surface is oriented along a plane direction perpendicular to the stacking direction, the movement of lithium ions is hindered.

  The oriented positive electrode plate 12 which is such an oriented polycrystal can be made thicker than an unoriented polycrystal. The thickness of the alignment positive electrode plate 12 is preferably 20 μm or more, more preferably 25 μm or more, further preferably 30 μm or more, and particularly preferably 35 μm or more, considering the active material capacity per unit area. The upper limit value of the thickness of the alignment positive electrode plate 12 is not particularly limited, but is preferably less than 100 μm and more preferably 90 μm or less in consideration of suppression of deterioration of battery characteristics (particularly increase in resistance value) due to repeated charge and discharge. 80 μm or less is more preferable, and 70 μm or less is particularly preferable.

  The aligned positive electrode plate 12 is preferably formed in a sheet shape. The alignment positive electrode plate 12 may be constituted by one positive electrode active material formed in a sheet shape, or may be constituted by arranging small pieces of the positive electrode active material formed in a sheet shape in layers. Good.

  The relative density of the aligned positive electrode plate 12 is preferably 75% or more and 99.97% or less, more preferably 80% or more and 99.95% or less, still more preferably 90% or more and 99.90% or less, and 95% or more and 99.88. % Or less is particularly preferable, and 97% to 99.85% is most preferable. The relative density of the aligned positive electrode plate 12 is basically preferably higher in consideration of capacity and energy density, but by increasing the relative density within the above range, the resistance value increases when charging and discharging are repeated. Can be suppressed. This is considered to be because stress can be relieved when the oriented positive electrode plate 12 expands and contracts moderately with the accumulation and release of lithium.

  In addition, about the structure and manufacturing method of the alignment positive electrode plate 12, it describes in detail in Unexamined-Japanese-Patent No. 2012-009193, Unexamined-Japanese-Patent No. 2012-009194, and patent 4745463. In this specification, the disclosure content of these three publications is incorporated.

2. Solid electrolyte layer 14
The solid electrolyte layer 14 is disposed on the aligned positive electrode plate 12. The solid electrolyte layer 14 is made of a lithium ion conductive material. The lithium ion conductive material is preferably at least one selected from the group of garnet ceramic materials, nitride ceramic materials, perovskite ceramic materials, phosphate ceramic materials, sulfide ceramic materials, and polymer materials. More preferred is at least one selected from the group consisting of garnet-based ceramic materials, nitride-based ceramic materials, perovskite-based ceramic materials, and phosphate-based ceramic materials.

The garnet-based ceramic material, _{(specifically,} such as _{Li 7 La 3 Zr 2 O 12} . Hereinafter, referred to as "LLZ based ceramics material".) Li-La-Zr- O -based material and Li-La-Ta- Examples thereof include O-based materials (specifically, Li ₇ La ₃ Ta ₂ O _{12 and the} like). Examples of the nitride ceramic material include Li ₃ N. Examples of the perovskite ceramic material include LLZ ceramic materials (specifically, LiLa _1-x Ti _x O ₃ (0.04 ≦ x ≦ 0.14) and the like). Examples of phosphate ceramic materials include lithium phosphate, lithium phosphate oxynitride (LiPON), Li-Al-Ti-PO, Li-Al-Ge-PO, and Li-Al-Ti-Si. —P—O (specifically, Li _{1 + x + y} Al _x Ti _2−x Si _y P _3−y O ₁₂ (0 ≦ x ≦ 0.4, 0 <y ≦ 0.6) and the like) can be mentioned.

  The solid electrolyte layer 14 is particularly preferably composed of an LLZ ceramic material and / or a LiPON ceramic material.

The LLZ ceramic material is an oxide sintered body having a garnet-type or garnet-like crystal structure containing Li, La, Zr, and O. Examples of the LLZ ceramic material include garnet ceramic materials such as Li ₇ La ₃ Zr ₂ O ₁₂ . The garnet-based ceramic material is a lithium ion conductive material that does not react even when directly in contact with the negative electrode layer 16. The LLZ ceramic material is excellent in sinterability, so it is easy to be densified and has high ionic conductivity. The crystal structure of the LLZ-based ceramic material is called an LLZ crystal structure, and the XRD pattern of the LLZ-based ceramic material is an X-ray diffraction file No. 1 of CSD (Cambridge Structural Database). Similar to 422259 (Li ₇ La ₃ Zr ₂ O ₁₂ ). Note that the LLZ ceramic material and No. Constituent elements are different from those of 422259, and Li concentration in ceramics may be different. Therefore, the LLZ ceramic material and No. The diffraction angle and the diffraction intensity ratio may differ from those of 422259.

  The ratio Li / La of the number of moles of Li to La in the LLZ ceramic material is preferably 2.0 or more and 2.5 or less. The molar ratio Zr / La of Zr to La in the LLZ ceramic material is preferably 0.5 or more and 0.67 or less.

  The LLZ-based ceramic material may contain Nb and / or Ta. By substituting a part of Zr in the LLZ-based ceramic material with either one or both of Nb and Ta, the conductivity can be improved more than before the replacement. The substitution amount (molar ratio) of Zr with Nb and / or Ta is preferably set such that the molar ratio of (Nb + Ta) / La is 0.03 or more and 0.20 or less. The LLZ ceramic material preferably further contains Al. The addition amount of Al in the sintered body is preferably 0.01 to 1% by mass. The molar ratio Al / La of La to La is preferably 0.008 to 0.12. The elements of Nb, Ta and Al may exist in the crystal lattice or may exist outside the crystal lattice. The LLZ-based ceramic material can be manufactured according to a known technique or by appropriately modifying a known technique.

  The solid electrolyte layer 14 has a contact surface 14 </ b> S that contacts the intermediate layer 15. The arithmetic average roughness Ra on the contact surface 14S is preferably 0.1 to 0.7 μm. As a result, when the all-solid lithium battery 10 is subjected to a heating process such as a reflow soldering process, melting and spheroidization of lithium metal contained in the negative electrode layer 16 to be described later are suppressed. The peeling of the layer 16 can be suppressed. The arithmetic average roughness Ra on the contact surface 14S is measured according to JIS 0601-2001.

  The thickness of the solid electrolyte layer 14 is not particularly limited, but can be 0.1 μm or more and 100 μm or less. The thickness of the solid electrolyte layer 14 is preferably 0.2 μm or more and 20 μm or less, and more preferably 0.3 μm or more and 4.0 μm or less in view of charge / discharge rate characteristics.

  As a method for forming the solid electrolyte layer 14, various particle jet coating methods, solid phase methods, solution methods, and gas phase methods can be used. Examples of the particle jet coating method include an aerosol deposition (AD) method, a gas deposition (GD) method, a powder jet deposition (PJD) method, a cold spray (CS) method, and a thermal spraying method. In particular, the aerosol deposition (AD) method can form a film at room temperature, so that generation of a composition shift during film formation and formation of a high resistance layer due to reaction with the alignment positive electrode plate 12 can be suppressed. Examples of the solid phase method include a tape lamination method and a printing method. In particular, in the tape lamination method, the thickness of the solid electrolyte layer 14 can be reduced, and the thickness can be easily controlled. Examples of the solution method include a solvothermal method, a hydrothermal synthesis method, a sol-gel method, a precipitation method, a microemulsion method, and a solvent evaporation method. In particular, the hydrothermal synthesis method can form crystal grains having high crystallinity at a low temperature. The microcrystals synthesized by the solution method may be deposited on the alignment positive electrode plate 12 or may be directly deposited on the alignment positive electrode plate 12. Examples of the gas phase method include laser deposition (PLD) method, sputtering method, evaporation condensation (PVD) method, gas phase reaction method (CVD) method, vacuum deposition method, molecular beam epitaxy (MBE) method and the like. In particular, the laser deposition (PLD) method can suppress the occurrence of composition shift and can form a film with relatively high crystallinity.

  In addition, the process for reducing interface resistance may be given to the interface of the alignment positive electrode plate 12 and the solid electrolyte layer 14. Specifically, the interface resistance can be lowered by covering the oriented positive electrode plate 12 and / or the solid electrolyte layer 14 with a film. Niobium oxide, titanium oxide, tungsten oxide, tantalum oxide, zirconium oxide, lithium / nickel composite oxide, lithium / titanium composite oxide, lithium / niobium compound, lithium / tantalum Examples thereof include compounds, lithium / tungsten compounds, lithium / titanium compounds, composite oxides thereof, and any combination thereof. The coating is preferably thin, for example, 20 nm or less.

3. Intermediate layer 15
The intermediate layer 15 is disposed on the solid electrolyte layer 14. The intermediate layer 15 includes a metal that can be alloyed with lithium. Examples of metals that can be alloyed with lithium include Al (aluminum), Si (silicon), Zn (zinc), Ga (gallium), Ge (germanium), Ag (silver), Au (gold), Pt (platinum), At least one selected from the group consisting of Cd (cadmium), In (indium), Sn (tin), Sb (antimony), Pb (lead), and Bi (bismuth) can be used. The metal that can be alloyed with lithium includes at least one selected from the group consisting of Au (gold), In (indium), Si (silicon), Sn (tin), Zn (zinc), and Al (aluminum). It is preferable. The metal that can be alloyed with lithium may be an alloy containing two or more elements such as Mg ₂ Si and Mg ₂ Sn.

  The thickness of the intermediate layer 15 is not particularly limited, but can be 5 nm or more. By setting the thickness of the intermediate layer 15 to 5 nm or more, when the intermediate layer 15 is formed by a sputtering method as will be described later, it is possible to suppress the occurrence of film defects in the intermediate layer 15 and form a continuous film. it can. As a result, the intermediate layer 15 can be charged in a short circuit and fine short circuit inspection process described later. The thickness of the intermediate layer 15 is preferably 10 nm or more and 1000 nm or less, and more preferably 50 nm or more and 500 nm or less.

  The intermediate layer 15 is formed by a sputtering method using a sputtering apparatus (for example, SC-701AT manufactured by Sanyu Electronics). For the formation of the intermediate layer 15, a metal that can be alloyed with lithium is used as a target.

4). Negative electrode layer 16
The negative electrode layer 16 is disposed on the intermediate layer 15. The negative electrode layer 16 contains lithium metal as a main component. The negative electrode layer 16 may be a lithium-containing metal film formed on the intermediate layer 15 or may be a lithium-containing metal foil placed on the intermediate layer 15. The lithium-containing metal film can be formed by a vacuum deposition method, a sputtering method, a CVD method, or the like.

  The thickness of the negative electrode layer 16 is not particularly limited, but can be 200 μm or less. In consideration of securing a large amount of lithium in the all-solid-state lithium battery 10 and increasing the energy density of the battery, the thickness of the negative electrode layer 16 is preferably 10 μm or more, more preferably 50 μm or more and 10 μm or less, and 40 μm or more and 10 μm or less. Is more preferably 20 μm or more and 10 μm or less.

(Configuration of exterior part 2)
As shown in FIG. 1, the exterior portion 2 includes a positive electrode exterior material 20, a negative electrode exterior material 24, and a sealing portion 26.

1. Cathode exterior material 20
The positive electrode exterior material 20 covers the outer side of the oriented positive electrode plate 12. The positive electrode exterior member 20 is electrically connected to the oriented positive electrode plate 12 of the unit battery 1 through the connection portion 3. The positive electrode exterior material 20 functions as a positive electrode current collector. The positive electrode exterior material 20 is made of metal. Examples of the metal include stainless steel, aluminum, copper, platinum, nickel and the like, and stainless steel is particularly preferable. The positive electrode exterior material 20 can be formed in a plate shape or a foil shape, and a foil shape is particularly preferable. Therefore, it is particularly preferable to use a stainless steel foil as the positive electrode exterior material 20. When the positive electrode exterior material 20 is formed in a foil shape, the thickness of the positive electrode exterior material 20 can be 1 to 30 μm, preferably 5 μm to 25 μm, and more preferably 10 μm to 20 μm.

  In the present embodiment, the positive electrode exterior member 20 has a counterbore-shaped recess 20a and a frame-shaped protrusion 20b formed on the outer periphery of the recess 20a.

2. Negative electrode packaging material 24
The negative electrode exterior member 24 is electrically connected to the negative electrode layer 16 of the unit battery 1. The negative electrode exterior material 24 functions as a negative electrode current collector. The negative electrode exterior material 24 is made of metal. The negative electrode exterior material 24 can be made of the same material as the positive electrode exterior material 20. Therefore, it is preferable to use a stainless steel foil as the negative electrode exterior material 24. When the negative electrode exterior material 24 is formed in a foil shape, the thickness of the negative electrode exterior material 24 can be 1 to 30 μm, preferably 5 μm to 25 μm, and more preferably 10 μm to 20 μm.

3. Sealing part 26
The sealing portion 26 seals a gap between the positive electrode exterior material 20 and the negative electrode exterior material 24. The sealing unit 26 suppresses intrusion of moisture into the all solid lithium battery 10. Moreover, in order to ensure the electrical insulation between the positive electrode exterior material 20 and the negative electrode exterior material 24, the resistivity of the sealing material is preferably 1 × 10 ⁶ Ωcm or more, more preferably 1 × 10 ⁷ Ωcm or more, and 1 × 10 ⁸ Ωcm or more is more preferable. Such a sealing part 26 can be comprised with an electrically insulating sealing material.

  As the sealing material, a resin-based sealing material containing a resin can be used. By using the resin-based sealing material, the sealing portion 26 can be formed at a relatively low temperature (for example, 400 ° C. or lower), so that the battery can be prevented from being broken or altered by heating.

  The sealing portion 26 can be formed by laminating resin films, dispensing liquid resin, or the like. As shown in FIG. 1, when the positive electrode exterior material 20 has the frame-shaped convex part 20b, it is preferable that the sealing part 26 is arrange | positioned between the convex part 20b and the negative electrode exterior material 24. As shown in FIG. Thereby, since the area | region sealed with the sealing part 26 can be made small, the penetration | invasion of a water | moisture content can be suppressed more.

(Configuration of connection unit 3)
As shown in FIG. 1, the connecting portion 3 includes a metal layer 22, a conductive adhesive layer 28, and an end insulating portion 18.

1. Metal layer 22
The metal layer 22 is disposed between the aligned positive electrode plate 12 and the conductive adhesive layer 28. By interposing the metal layer 22 between the aligned positive electrode plate 12 and the conductive adhesive layer 28, the electronic conductivity between the aligned positive electrode plate 12 and the conductive adhesive layer 28 can be improved. The metal layer 22 can be made of a metal having low electron conduction resistance and reactivity with the aligned positive electrode plate 12 and the conductive adhesive layer 28, respectively. As such a metal layer 22, an Au sputter layer formed by sputtering on the plate surface of the oriented positive electrode plate 12 can be used. The thickness of the metal layer 22 can be 10 nm or more and 1000 nm or less, and preferably 50 nm or more and 500 nm or less.

2. Conductive adhesive layer 28
The conductive adhesive layer 28 is disposed between the positive electrode exterior material 20 and the metal layer 22. The conductive adhesive layer 28 ensures the electrical connection between the aligned positive electrode plate 12 and the positive electrode exterior material 20 by mechanically and firmly joining the positive electrode exterior material 20 and the metal layer 22. The conductive adhesive layer 28 includes a conductive material and an adhesive. As the conductive material, conductive carbon or the like can be used. As the adhesive, an epoxy-based resin material can be used. The thickness of the conductive adhesive layer 28 is not particularly limited, but can be 5 μm or more and 100 μm or less, and preferably 10 μm or more and 50 μm or less.

3. End insulation 18
The end insulating portion 18 is filled in a gap between the oriented positive electrode plate 12 and the exterior portion 2. The end insulating portion 18 only needs to be able to suppress a short circuit between the aligned positive electrode plate 12 and the negative electrode layer 16 while relaxing the stress accompanying expansion of the aligned positive electrode plate 12 during charging, and the material and shape thereof are particularly limited. However, it is preferable to include an organic polymer material that can be adhered or adhered to the oriented positive electrode plate 12.

(Inspection method of short circuit and fine short circuit in all-solid-state lithium battery 10)
Next, a method for inspecting a short circuit and a fine short circuit in the all solid lithium battery 10 will be described with reference to the drawings. FIG. 3 is a flowchart showing a method for inspecting a short circuit and a fine short circuit in the all-solid-state lithium battery 10.

  In step S1, an oriented positive electrode plate 12 (an example of a positive electrode layer) is formed. About the formation method of the alignment positive electrode plate 12, it describes in Unexamined-Japanese-Patent No. 2012-009193, Unexamined-Japanese-Patent No. 2012-009194, and patent 4745463.

  In step S2, a solid electrolyte layer 14 made of a lithium ion conductive material is formed on the alignment positive electrode plate 12 by various particle jet coating methods, solid phase methods, solution methods, gas phase methods, and the like.

In step S3, the intermediate layer 15 containing a metal that can be alloyed with lithium is formed on the solid electrolyte layer 14 by sputtering. As the sputtering apparatus, for example, SC-701AT manufactured by Sanyu Electronics can be used. If no short circuit or slight short circuit occurs in the intermediate layer 15 formed by the sputtering method, the intermediate layer 15 is negatively charged from the principle of the sputtering method, so that lithium ions (Li ⁺ ) are transferred from the oriented positive electrode plate 12 to the solid electrolyte layer. 14 moves to the intermediate layer 15 through 14 to deposit Li metal or form a lithium alloy to be charged. On the other hand, if the intermediate layer 15 formed by the sputtering method is short-circuited or slightly short-circuited, the intermediate layer 15 is not negatively charged. Therefore, lithium ions (Li ⁺ ) pass from the oriented positive electrode plate 12 through the solid electrolyte layer 14. In this case, it does not move to the intermediate layer 15 or, even if it has moved once, self-discharge occurs through the short-circuit portion, so that it does not enter the charged state.

  In step S <b> 4, the negative electrode layer 16 containing lithium is formed on the intermediate layer 15. When the lithium-containing metal film is used as the negative electrode layer 16, the negative electrode layer 16 can be formed by a vacuum deposition method, a sputtering method, a CVD method, or the like. When the lithium-containing metal foil is used as the negative electrode layer 16, the negative electrode layer 16 can be formed by placing the metal foil on the intermediate layer 15. Thus, the unit battery 1 is completed.

  In step S5, the open circuit voltage of the unit battery 1 is measured. Specifically, the open end voltage between the aligned positive electrode plate 12 and the negative electrode layer 16 is measured by a voltmeter connected to the aligned positive electrode plate 12 and the negative electrode layer 16. At this time, if a short circuit or a fine short circuit does not occur inside, the unit battery 1 is in a charged state, and thus an open-ended voltage equal to or higher than a predetermined threshold is detected. On the other hand, if a short circuit or a slight short circuit occurs inside, the unit battery 1 is not in a charged state, and thus an open-circuit voltage less than a predetermined threshold is detected. A method for acquiring the predetermined threshold will be described in an embodiment described later.

  In step S6, it is determined whether or not the open-circuit voltage measured in step S5 is greater than or equal to a predetermined threshold value. If it is determined that the open-circuit voltage is equal to or higher than the predetermined threshold, the unit battery 1 is a non-defective product, and the process proceeds to step S7. When it is determined that the open-circuit voltage is not equal to or higher than the predetermined threshold (that is, less than the predetermined threshold), the unit battery 1 is a defective product in which a short circuit or a fine short circuit exists, and thus the process ends.

  In step S <b> 7, the two unit batteries 1 are sealed by the exterior part 2 and the connection part 3. In step S7, two connecting portions 3 (the metal layer 22, the conductive adhesive layer 28, and the end insulating portion 18) are formed, and the exterior portion 2 (two positive electrode exterior materials 20, one negative electrode exterior). A step of forming the material 24 and the two sealing portions 26) is included. However, at least a part of the process of step S7 may be divided between steps S1 to S6.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and various modifications or changes can be made without departing from the scope of the present invention.

  In the above embodiment, the all solid lithium battery 10 includes the aligned positive electrode plate 12 as the positive electrode layer, but may include a positive electrode layer containing a known positive electrode active material instead of the aligned positive electrode plate 12. Such a positive electrode layer is disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 2012-146512 and 2013-105708.

  In the above embodiment, the all solid lithium battery 10 includes the two unit batteries 1, but may include one unit battery 1 or three or more unit batteries 1. When the all solid lithium battery 10 includes two or more unit cells 1, the unit cells 1 may be connected in parallel or in series.

  In the embodiment described above, the two unit batteries 1 are arranged so as to sandwich the negative electrode exterior material 24, but may be arranged so as to sandwich the positive electrode exterior material 20. In this case, the two negative electrode exterior members 24 may be disposed outside the two unit cells 1.

  In the above embodiment, the all solid lithium battery 10 includes the exterior part 2, but the exterior part 2 may not be provided. In this case, an electrode extraction tab or the like may be connected to each of the oriented positive electrode plate 12 and the negative electrode layer 16 of the unit battery 1.

  In the above embodiment, the exterior portion 2 has the sealing portion 26, but may not have the sealing portion 26.

  In the said embodiment, although the all-solid-state lithium battery 10 was provided with the connection part 3, it does not need to be provided with the connection part 3. FIG. In this case, the oriented positive electrode plate 12 may be brought into direct contact with the positive electrode exterior member 20.

  In the above embodiment, the connecting portion 3 includes the metal layer 22 and the end insulating portion 18, but may not include at least one of the metal layer 22 and the end insulating portion 18.

  Although not particularly mentioned in the above embodiment, when it is determined in step S6 in FIG. 3 that the unit battery 1 is defective, a repair operation for a short circuit or a fine short circuit in the unit battery 1 may be performed.

  Hereinafter, examples of the all solid lithium battery according to the present invention will be described, but the present invention is not limited to the examples described below.

(Production of sample Nos. 1 to 15)
1. 1. Production of Oriented Positive Electrode Plate 1.1 Production of Green Sheet First, a Co ₃ O ₄ raw material powder (manufactured by Shodo Chemical Industry Co., Ltd.) having a volume standard D50 particle size of 0.3 μm was used. Bi ₂ O ₃ (manufactured by Taiyo Mining Co., Ltd.) was added at a rate of 5 wt% to obtain a mixed powder. Next, 100 parts by weight of this mixed powder, 100 parts by weight of a dispersion medium (toluene: isopropanol = 1: 1), 10 parts by weight of a binder (polyvinyl butyral: product number BM-2, manufactured by Sekisui Chemical Co., Ltd.), plastic 4 parts by weight of an agent (DOP: Di (2-ethylhexyl) phthalate, manufactured by Kurokin Kasei Co., Ltd.) and 2 parts by weight of a dispersant (product name: Leodol SP-O30, manufactured by Kao Corporation) were mixed. Next, a slurry having a viscosity of 4000 cP was prepared while degassing the mixture by stirring under reduced pressure. The viscosity of the slurry was measured with an LVT viscometer manufactured by Brookfield. Next, a green sheet was produced by forming the prepared slurry into a sheet on a PET film by a doctor blade method. The thickness of the green sheet after drying was 40 μm.

1.2 Production of Oriented Sintered Plate The green sheet peeled off from the PET film was cut into a 40 mm square with a cutter to form a small piece of green sheet. Next, a small piece of green sheet was placed in the center of a zirconia setter (dimension 90 mm square, height 1 mm) having an embossing process with a protrusion height of 300 μm. Next, after the small piece of the green sheet was fired at 1300 ° C. for 5 hours, the temperature was decreased at a temperature decrease rate of 50 ° C./h. Next, a portion not welded to the zirconia setter was taken out as a Co ₃ O ₄ oriented sintered plate.

1.3 Introduction of Lithium LiOH · H ₂ O powder (manufactured by Wako Pure Chemical Industries, Ltd.) was pulverized to 1 μm or less with a jet mill, and then dispersed in ethanol to prepare a slurry. Next, the slurry was applied to a Co ₃ O ₄ oriented sintered plate so that Li / Co = 1.3, and then dried. Next, the oriented sintered plate coated with the slurry was placed on a zirconia setter. Next, the oriented sintered plate to which the slurry was applied was heat-treated in the atmosphere at 840 ° C. for 20 hours to produce a LiCoO ₂ oriented sintered plate having a thickness of 45 μm.

2. 2. Production of Lithium Battery 2.1 Production of Metal Layer An Au film as a metal layer is formed on the first main surface of the LiCoO ₂ oriented sintered plate by sputtering using an ion sputtering apparatus (manufactured by JEOL, JFC-1500). did. The thickness of the metal layer was 1000 mm.

2.2 Fixing of Oriented Positive Electrode Plate A LiCoO ₂ oriented sintered plate on which a metal layer was formed was cut out at 10 mm to prepare an oriented positive plate. Next, the metal layer on the oriented positive electrode plate was fixed to a stainless steel current collector plate (thickness: 100 μm) as a positive electrode exterior material using an epoxy-based conductive adhesive in which conductive carbon was dispersed. As a result, a flat laminated body in which the oriented positive electrode plate, the metal layer, the conductive adhesive, and the positive electrode exterior material were sequentially laminated was produced.

2.3 Formation of Solid Electrolyte Layer A lithium phosphate sintered compact target having a diameter of 4 inches (about 10 cm) was prepared. Next, by using an RF magnetron method using a sputtering apparatus (SPF-430H, manufactured by Canon Anelva), gas species N ₂ is collided with the target under the conditions of a vacuum degree of 0.2 Pa and an output of 0.2 kW, thereby aligning the positive electrode. A LiPON-based sputtered film was formed as a solid electrolyte layer on the second main surface of the plate. The thickness of the solid electrolyte layer was 3.5 μm.

2.4 Formation of Intermediate Layer An Au foil having a diameter of 2 inches (about 5 cm) was prepared as a target. Next, the gas species air adjusted so that the degree of vacuum is 1 × 10 ⁻² Pa and the current value is 3 to 4 mA is collided with the target by a bipolar sputtering method using a sputtering apparatus (SC-701AT manufactured by Sanyu Electronics). As a result, an Au sputtered film was formed as an intermediate layer on the solid electrolyte layer. The thickness of the intermediate layer was 100 nm.

2.5 Formation of Negative Electrode Layer A tungsten boat on which lithium metal was placed was prepared. Using a vacuum deposition apparatus (Sanyu Electronics, carbon coater SVC-700), Li was evaporated by resistance heating to form a Li deposited film on the intermediate layer as a negative electrode layer. Thus, the unit battery was completed.

2.6 Measurement of Open End Voltage of Unit Battery The open end voltage of the unit battery was measured by connecting a voltmeter to the oriented positive electrode plate and the negative electrode layer of the unit battery.

2.7 Sealing by Exterior Unit The unit cell was sealed with an Al laminate film to which an electrode extraction tab was bonded. As described above, sample no. All-solid lithium batteries according to 1 to 15 were completed.

(Production of sample Nos. 16 to 30)
Except that no Au sputtered film was formed as the intermediate layer, the above sample No. Sample No. 1 to 15 in the same process. 16-30 were produced. That is, sample No. In 16-30, the Li vapor deposition film | membrane as a negative electrode layer was directly formed on the solid electrolyte layer. And sample no. Similarly to 1-15, the open circuit voltage of the unit cell was measured.

(Measurement of self-discharge rate)
Sample No. About 1-30, the self-discharge rate was measured. Specifically, sample no. After performing constant-current constant-voltage charging up to 4 V in 1 to 30, it was left in a charged state in a constant temperature bath at 20 ° C. for 7 days. And sample no. Self-discharge rates (%) of 1-30 were measured. A sample with a self-discharge rate of less than 20% is determined as a non-defective product, a sample with a self-discharge rate of 20% or more and less than 80% is determined as a fine short-circuit product, and a sample with a self-discharge rate of 80% or more is short-circuited. It was identified as a product. A product with a slight short circuit and a product with a short circuit are defective.

  Here, FIG. It is a scatter diagram which shows the relationship between the open end voltage of a unit battery, and the self-discharge rate for 7 days about 1-15. As is clear from FIG. In 1 to 15, a high correlation was confirmed between the open-circuit voltage and the self-discharge rate. Therefore, in the unit battery in which an intermediate layer is provided between the solid electrolyte layer and the negative electrode layer by sputtering, non-defective products and defective products (including short-circuited products and micro-short-circuited products) are determined based on the open-circuit voltage of the unit battery. It was confirmed that it was possible to discriminate accurately. In the example shown in FIG. 4, the open-circuit voltage threshold (an example of a predetermined threshold) is set to 2 V, a unit cell with an open-circuit voltage of 2 V or more is determined as a non-defective product, and the open-circuit voltage is less than 2 V. The unit battery can be identified as a defective product.

  On the other hand, FIG. It is a scatter diagram which shows the relationship between the open end voltage of a unit battery, and the self-discharge rate for 7 days about 16-30. As is clear from FIG. In 16-30, there is no correlation between the open circuit voltage and the self-discharge rate. Therefore, in the unit battery in which the intermediate layer is not provided by the sputtering method between the solid electrolyte layer and the negative electrode layer, it was not possible to discriminate between a good product and a defective product based on the open-circuit voltage of the unit battery.

DESCRIPTION OF SYMBOLS 10 All-solid-state lithium battery 12 Oriented positive electrode plate 14 Solid electrolyte layer 15 Intermediate layer 16 Negative electrode layer 18 End part insulation part 20 Positive electrode exterior material 22 Metal layer 24 Negative electrode exterior material 26 Sealing part 28 Conductive adhesive

Claims (2)

A positive electrode layer, a solid electrolyte layer formed on the positive electrode layer, an intermediate layer containing a metal that can be alloyed with lithium formed on the solid electrolyte layer by a sputtering method, and a lithium formed on the intermediate layer An inspection method for an all-solid-state lithium battery comprising a step of determining the presence or absence of a short circuit and a fine short circuit in the unit battery by comparing an open end voltage of the unit battery having a negative electrode layer with a predetermined threshold. Forming a positive electrode layer;
Forming a solid electrolyte layer on the positive electrode layer;
Forming an intermediate layer containing a metal that can be alloyed with lithium on the solid electrolyte layer by a sputtering method;
Forming a negative electrode layer containing lithium on the intermediate layer;
Determining the presence or absence of a short circuit and a micro short circuit in the unit cell by comparing the open end voltage of the unit cell having the positive electrode layer, the solid electrolyte layer, the intermediate layer and the negative electrode layer with a predetermined threshold;
A method for producing an all-solid-state lithium battery.

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