WO2020012734A1 - Batterie rechargeable au lithium-ion - Google Patents

Batterie rechargeable au lithium-ion Download PDF

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Publication number
WO2020012734A1
WO2020012734A1 PCT/JP2019/014775 JP2019014775W WO2020012734A1 WO 2020012734 A1 WO2020012734 A1 WO 2020012734A1 JP 2019014775 W JP2019014775 W JP 2019014775W WO 2020012734 A1 WO2020012734 A1 WO 2020012734A1
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layer
solid electrolyte
lithium ion
positive electrode
ion secondary
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PCT/JP2019/014775
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English (en)
Japanese (ja)
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安田　剛規
坂脇　彰
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昭和電工株式会社
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a lithium ion secondary battery.
  • a lithium ion secondary battery has a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte having lithium ion conductivity and disposed between the positive electrode and the negative electrode.
  • Patent Literature 1 describes that Li 3 PO 4-x N x (generally referred to as LiPON) obtained by adding nitrogen to lithium phosphate (Li 3 PO 4 ) is used as a solid electrolyte. I have.
  • the capacity of a lithium ion secondary battery gradually decreases over time after charging, even if it is not particularly used.
  • the ratio of the capacity of the lithium ion secondary battery at the time when a predetermined period has elapsed to the initial capacity after the completion of charging is referred to as a capacity retention rate.
  • the capacity retention ratio tends to decrease, and the time until the lithium ion secondary battery does not function as a power source after charging is shortened even if not particularly used. there were.
  • An object of the present invention is to suppress a decrease in capacity retention in a lithium ion secondary battery using LiPON as a solid electrolyte.
  • the lithium ion secondary battery of the present invention includes a positive electrode layer containing a positive electrode active material, a first solid electrolyte layer containing Li 3 PO 4 , and a lithium ion secondary battery containing LiPON in which part of oxygen in Li 3 PO 4 is replaced with nitrogen. It has two solid electrolyte layers and a negative electrode layer containing a negative electrode active material in order. In such a lithium ion secondary battery, the thickness of the first solid electrolyte layer may be smaller than the thickness of the second solid electrolyte layer. Further, the first solid electrolyte layer and the second solid electrolyte layer may each have an amorphous structure. Further, the positive electrode layer includes a LiNiO 2 and Li 3 PO 4, the ratio of LiNiO 2 and Li 3 PO 4 in the positive electrode layer is, in molar ratio, 9: 1 to 3: 2 by weight It can be characterized.
  • the lithium ion secondary battery of the present invention includes a positive electrode layer containing a positive electrode active material and a solid layer containing lithium (Li), phosphate (PO 4 3- ), and nitrogen (N).
  • An electrolyte layer and a negative electrode layer containing a negative electrode active material are sequentially provided, and the solid electrolyte layer is such that the concentration of nitrogen on the side facing the positive electrode layer is lower than the concentration of nitrogen on the side facing the negative electrode layer. It is characterized by.
  • the solid electrolyte layer may be characterized in that the concentration of nitrogen on the side facing the positive electrode layer is 0%.
  • a lithium ion secondary battery of the present invention includes a positive electrode collector layer made of a metal or an alloy, an underlayer that does not contain Li 3 PO 4 comprises LiNiO 2, LiNiO 2 and Li 3 and covering material the positive electrode layer containing PO 4, Li 3 and the first solid electrolyte layer containing no LiNiO 2 comprises PO 4, second solid electrolyte comprising a LiPON a portion of the oxygen was replaced with nitrogen in Li 3 PO 4 And a negative electrode layer containing a negative electrode active material.
  • the second solid electrolyte layer is formed of a platinum group element (Ru, Rh, Pd, Os, Ir, Pt), gold (Au), aluminum (Al), or an alloy thereof.
  • a metal layer is formed, and the negative electrode layer is made of lithium alloyed with a metal forming the metal layer.
  • FIG. 2 is a diagram illustrating a cross-sectional configuration of a lithium ion secondary battery according to an embodiment.
  • 4 is a flowchart illustrating a method for manufacturing a lithium ion secondary battery according to an embodiment.
  • FIG. 3 is a diagram illustrating a cross-sectional configuration of a lithium ion secondary battery of a first comparative example. It is a figure showing the section composition of the lithium ion secondary battery of the 2nd comparative example. It is a figure showing the section composition of the lithium ion secondary battery of the 3rd comparative example.
  • FIG. 1 is a diagram showing a cross-sectional configuration of a lithium ion secondary battery 1 of the present embodiment.
  • the lithium ion secondary battery 1 of the present embodiment has a structure in which a plurality of layers are stacked. After forming a basic structure by a so-called film forming process, the first charge / discharge operation is performed. Completes the structure.
  • the lithium ion secondary battery 1 shown in FIG. 1 includes a substrate 10, an underlayer 20 laminated on the substrate 10, a positive electrode layer 30 laminated on the underlayer 20, and a solid layer laminated on the positive electrode layer 30. And an electrolyte layer 40.
  • the solid electrolyte layer 40 covers the peripheral edges of both the base layer 20 and the positive electrode layer 30 and the ends thereof are directly laminated on the substrate 10, so that the solid electrolyte layer 40 covers the base layer 20 and the positive electrode layer 30 together with the substrate 10.
  • the lithium ion secondary battery 1 has a holding layer 50 stacked on the solid electrolyte layer 40, a diffusion prevention layer 60 stacked on the holding layer 50, and a negative electrode collection layer stacked on the diffusion prevention layer 60. And an electric conductor layer 70.
  • the substrate 10 serves as a base for stacking the base layer 20 to the negative electrode current collector layer 70 by a film forming process.
  • the material forming the substrate 10 is not particularly limited, and various materials such as metal, glass, ceramics, and resin can be adopted.
  • the substrate 10 is made of a metal plate having electron conductivity.
  • the substrate 10 functions as a positive electrode current collector layer that collects electric power into the positive electrode layer 30 via the base layer 20.
  • a stainless steel foil (plate) having higher mechanical strength than copper, aluminum, or the like is used as the substrate 10.
  • a metal foil plated with a conductive metal such as tin, copper, or chromium may be used.
  • the thickness of the substrate 10 can be, for example, not less than 20 ⁇ m and not more than 2000 ⁇ m. If the thickness of the substrate 10 is less than 20 ⁇ m, the strength of the lithium ion secondary battery 1 may be insufficient. On the other hand, when the thickness of the substrate 10 exceeds 2000 ⁇ m, the volume energy density and the weight energy density decrease due to an increase in the thickness and weight of the battery.
  • the substrate 10 has a front surface 10a and a back surface 10b, and the base layer 20 to the negative electrode current collector layer 70 are stacked on the front surface 10a.
  • the maximum height Rmax of the front surface 10a and the back surface 10b of the substrate 10 is about 300 nm to 500 nm.
  • the base layer 20 is a solid thin film, which enhances the adhesion between the substrate 10 and the positive electrode layer 30, and forms a metal material such as stainless steel forming the substrate 10 and Li 3 PO 4 (phosphoric acid) forming the positive electrode layer 30. (Lithium: described later in detail) is a barrier for suppressing direct contact.
  • the underlayer 20 is made of a metal or a metal compound, which has electron conductivity and is hardly corroded by Li + (lithium ion) or PO 4 3- (phosphate ion) constituting Li 3 PO 4. Can be used.
  • the underlayer 20 is made of LiNiO 2 (nickel phosphate). LiNiO 2 is sometimes used as a positive electrode material of the lithium ion secondary battery 1.
  • the thickness of the underlayer 20 can be, for example, not less than 5 nm and not more than 50 ⁇ m. If the thickness of the underlayer 20 is less than 5 nm, the function as a barrier is reduced, which is not practical. On the other hand, when the thickness of the underlayer 20 exceeds 50 ⁇ m, the internal resistance of the battery increases, which is disadvantageous for high-speed charging and discharging.
  • a known film forming technique such as various PVD (physical vapor deposition) or various CVD (chemical vapor deposition) may be used, but from the viewpoint of production efficiency, a sputtering method or a vacuum method is used. It is desirable to use an evaporation method.
  • the positive electrode layer 30 is a solid thin film and contains a positive electrode active material that releases lithium ions during charging and absorbs lithium ions during discharging.
  • the positive electrode active material constituting the positive electrode layer 30 is, for example, a kind selected from manganese (Mn), cobalt (Co), nickel (Ni), iron (Fe), molybdenum (Mo), and vanadium (V). It is possible to use those made of various materials such as oxides, sulfides, and phosphorus oxides containing the above metals.
  • the positive electrode layer 30 may be a mixed material positive electrode further containing a solid electrolyte.
  • the positive electrode layer 30 is composed of a mixed positive electrode including a positive electrode active material and a solid electrolyte made of an inorganic material (inorganic solid electrolyte). More specifically, the positive electrode layer 30 of the present embodiment has a solid electrolyte region mainly containing an inorganic solid electrolyte and a positive electrode region mainly containing a positive electrode active material.
  • the inorganic solid electrolyte forming the solid electrolyte region and the positive electrode active material forming the positive electrode region are mixed while maintaining each.
  • one is a matrix (base material) and the other is a filler (particle).
  • the solid electrolyte region be a matrix and the positive electrode region be a filler.
  • the same LiNiO 2 as the underlayer 20 is used as the positive electrode active material constituting the positive electrode layer 30.
  • Li 3 PO 4 lithium phosphate
  • the ratio between the positive electrode active material and the inorganic solid electrolyte in the positive electrode layer 30 may be appropriately selected.
  • the molar ratio of the positive electrode active material to the inorganic solid electrolyte is from 9: 1 (90%: 10%) to 3: 2 (60%: 40%).
  • the thickness of the positive electrode layer 30 can be, for example, not less than 10 nm and not more than 40 ⁇ m.
  • the thickness of the positive electrode layer 30 is less than 10 nm, the capacity of the obtained lithium ion secondary battery 1 becomes too small, which is not practical.
  • the thickness of the positive electrode layer 30 exceeds 40 ⁇ m, it takes too much time to form the layer, and the productivity is reduced.
  • the thickness of the positive electrode layer 30 may be more than 40 ⁇ m.
  • a known film forming method such as various PVD or various CVD may be used, but it is preferable to use a sputtering method from the viewpoint of production efficiency.
  • the solid electrolyte layer 40 is a solid thin film made of an inorganic material, and includes an inorganic solid electrolyte capable of moving lithium ions by an externally applied electric field. Then, the solid electrolyte layer 40 of the present embodiment is stacked on the first solid electrolyte layer 41 and the first solid electrolyte layer 41 that are stacked on the positive electrode layer 30, and is an object to be stacked on the holding layer 50. A second solid electrolyte layer.
  • the first solid electrolyte layer 41 of the present embodiment is made of the same Li 3 PO 4 as the inorganic solid electrolyte in the positive electrode layer 30.
  • the thickness of the first solid electrolyte layer 41 can be, for example, 5 nm or more and 50 nm or less. When the thickness of the first solid electrolyte layer 41 is less than 5 nm, current leakage between the positive electrode layer 30 and the holding layer 50 easily occurs in the obtained lithium ion secondary battery 1. On the other hand, when the thickness of the first solid electrolyte layer 41 exceeds 50 nm, the internal resistance of the battery increases, which is disadvantageous for high-speed charging and discharging.
  • a known film forming method such as various PVD or various CVD may be used, but from the viewpoint of production efficiency, it is preferable to use a sputtering method.
  • the second solid electrolyte layer 42 of the present embodiment includes LiPON (Li 3 PO 4-x N x (0 ⁇ x) in which a part of oxygen in Li 3 PO 4 constituting the first solid electrolyte layer 41 is substituted with nitrogen. ⁇ 1)).
  • the thickness of the second solid electrolyte layer 42 can be, for example, 10 nm or more and 10 ⁇ m or less. If the thickness of the second solid electrolyte layer 42 is less than 10 nm, current leakage between the positive electrode layer 30 and the holding layer 50 tends to occur in the obtained lithium ion secondary battery 1. On the other hand, if the thickness of the second solid electrolyte layer 42 exceeds 10 ⁇ m, the internal resistance of the battery increases, which is disadvantageous for high-speed charging and discharging.
  • a known film forming method such as various PVD or various CVD may be used, but from the viewpoint of production efficiency, it is preferable to use a sputtering method.
  • the first solid electrolyte layer 41 is made of Li 3 PO 4 and the second solid electrolyte layer 42 is made of LiPON. That is, both the first solid electrolyte layer 41 and the second solid electrolyte layer 42 contain lithium, phosphorus, and oxygen, respectively.
  • the volume resistivity of Li 3 PO 4 forming the first solid electrolyte layer 41 is higher than that of LiPON forming the second solid electrolyte layer 42.
  • the side provided with the first solid electrolyte layer 41 in contact with the positive electrode layer 30 is closer to the side provided with the second solid electrolyte layer 42 in contact with the holding layer 50. Also, the resistance value per unit thickness is high.
  • the thickness of the first solid electrolyte layer 41 is smaller than the thickness of the second solid electrolyte layer 42, in the order of two digits or more. More preferably, it is reduced.
  • the holding layer 50 as an example of a metal layer is a solid thin film and has a function of holding lithium ions during charging and abandoning lithium ions during discharging.
  • the point that the holding layer 50 of the present embodiment does not include the negative electrode active material itself and is configured to hold lithium functioning as the negative electrode active material therein is different from a general negative electrode layer. Is different.
  • the holding layer 50 of the present embodiment has a porous structure, and is constituted by a porous portion (not shown) in which a large number of holes are formed.
  • the porousization of the holding layer 50 that is, the formation of the porous portion is performed in accordance with the first charge / discharge operation after the film formation, and the details thereof will be described later.
  • a platinum group element Ru, Rh, Pd, Os, Ir, Pt
  • gold Au
  • the holding layer 50 of the present embodiment can be made of a polycrystal of the above-mentioned noble metal or an alloy thereof.
  • the holding layer 50 is made of platinum.
  • the thickness of the holding layer 50 can be, for example, not less than 10 nm and not more than 40 ⁇ m.
  • the thickness of the holding layer 50 is less than 10 nm, the ability to hold lithium becomes insufficient.
  • the thickness of the holding layer 50 exceeds 40 ⁇ m, the internal resistance of the battery increases, which is disadvantageous for high-speed charging and discharging.
  • the thickness of the holding layer 50 may be more than 40 ⁇ m.
  • a known film forming method such as various PVD or various CVD may be used, but from the viewpoint of production efficiency, it is preferable to use a sputtering method.
  • a method for manufacturing the porous holding layer 50 it is desirable to employ a method of performing charging and discharging, as described later.
  • the diffusion prevention layer 60 is a solid thin film and is for suppressing the diffusion of lithium ions held in the holding layer 50 to the outside of the lithium ion secondary battery 1.
  • a material having an amorphous structure and made of a metal or an alloy can be used.
  • the diffusion prevention layer 60 is preferably made of a metal or an alloy that does not form an intermetallic compound with lithium. Among them, from the viewpoint of corrosion resistance, chromium (Cr) alone or an alloy containing chromium is preferable. Is preferred.
  • the diffusion preventing layer 60 may be formed by laminating a plurality of amorphous layers having different constituent materials (for example, a laminated structure of an amorphous chromium layer and an amorphous chromium titanium alloy layer).
  • the “amorphous structure” in the present embodiment includes not only a structure having an amorphous structure as a whole but also a structure in which microcrystals are precipitated in the amorphous structure. .
  • the diffusion preventing layer 60 is made of an alloy of chromium and titanium (CrTi).
  • the metal (alloy) that can be used for the diffusion preventing layer 60 include, in addition to CrTi, ZrCuAlNiPdP, CuZr, FeZr, TiZr, CoZrNb, NiNb, NiTiNb, NiP, CuP, NiPCu, NiTi, CrTi, AlTi, FeSiB. , AuSi, and the like.
  • the thickness of the diffusion preventing layer 60 can be, for example, 10 nm or more and 40 ⁇ m or less. When the thickness of the diffusion prevention layer 60 is less than 10 nm, it is difficult for the diffusion prevention layer 60 to block lithium that has passed through the holding layer 50 from the solid electrolyte layer 40 side. On the other hand, if the thickness of the diffusion prevention layer 60 exceeds 40 ⁇ m, the internal resistance of the battery increases, which is disadvantageous for high-speed charging and discharging.
  • the diffusion preventing layer 60 As a method of manufacturing the diffusion preventing layer 60, a known film forming method such as various PVD or various CVD may be used, but from the viewpoint of production efficiency, it is preferable to use a sputtering method.
  • a sputtering method when the diffusion prevention layer 60 is made of the above-described chromium-titanium alloy, the chromium-titanium alloy tends to be amorphous when the sputtering method is employed.
  • the negative electrode current collector layer 70 is a solid thin film having electron conductivity, and has a function of collecting current to the holding layer 50.
  • the material constituting the negative electrode current collector layer 70 is not particularly limited as long as it has electron conductivity, and various metals and conductive materials including alloys of various metals may be used. it can.
  • a chemically stable material for example, a platinum group element (Ru, Rh, Pd, Os, Ir, Pt) or gold. (Au) or an alloy thereof is preferable.
  • negative electrode current collector layer 70 is made of the same platinum as holding layer 50. However, unlike the holding layer 50, the negative electrode current collector layer 70 does not have a porous structure.
  • the thickness of the negative electrode current collector layer 70 can be, for example, not less than 5 nm and not more than 50 ⁇ m. If the thickness of the negative electrode current collector layer 70 is less than 5 nm, the corrosion resistance and the current collecting function will be reduced, which is not practical. On the other hand, if the thickness of the negative electrode current collector layer 70 exceeds 50 ⁇ m, the internal resistance of the battery increases, which is disadvantageous for high-speed charging and discharging.
  • the negative electrode current collector layer 70 As a method for manufacturing the negative electrode current collector layer 70, a known film forming method such as various PVD or various CVD may be used, but it is preferable to use a sputtering method from the viewpoint of production efficiency.
  • a known film forming method such as various PVD or various CVD may be used, but it is preferable to use a sputtering method from the viewpoint of production efficiency.
  • FIG. 2 is a flowchart illustrating a method of manufacturing the lithium ion secondary battery according to the present embodiment.
  • the substrate 10 is mounted on a sputtering device (not shown), and an underlayer forming step of forming the underlayer 20 on the substrate 10 is performed (step 20).
  • a positive electrode layer forming step of forming the positive electrode layer 30 on the base layer 20 is performed by the above-mentioned sputtering apparatus (Step 30).
  • a solid electrolyte layer forming step of forming the solid electrolyte layer 40 on the positive electrode layer 30 is performed by the sputtering device (step 40).
  • a first solid electrolyte layer forming step of forming the first solid electrolyte layer 41 on the positive electrode layer 30 is performed (Step 41), and the first solid electrolyte layer 41 is formed on the first solid electrolyte layer 41.
  • a second solid electrolyte layer forming step of forming the second solid electrolyte layer 42 is performed (Step 42).
  • a holding layer forming step of forming the holding layer 50 on the second solid electrolyte layer 42 of the solid electrolyte layer 40 is performed by the sputtering device (step 50).
  • a diffusion prevention layer forming step of forming the diffusion prevention layer 60 on the holding layer 50 is performed by the above-mentioned sputtering apparatus (Step 60).
  • a negative electrode current collector layer forming step of forming the negative electrode current collector layer 70 on the diffusion preventing layer 60 is performed by the sputtering device (step 70).
  • the basic structure of the lithium ion secondary battery 1 is obtained.
  • the basic structure of the lithium ion secondary battery 1 is removed from the sputtering device.
  • an initial charging step of performing the first charging of the basic structure of the lithium ion secondary battery 1 removed from the sputtering apparatus is performed (Step 80).
  • an initial discharge step (an example of a discharge step) for performing a first discharge is performed on the charged basic structure of the lithium ion secondary battery 1 (step 90).
  • the holding layer 50 is made porous, that is, a porous portion and a large number of pores are formed, and the lithium ion secondary battery 1 shown in FIG. 1 is obtained.
  • a positive electrode of a DC power supply is connected to the substrate 10 functioning as a positive electrode current collector layer, and a negative electrode of the DC power supply is connected to the negative electrode current collector layer 70, respectively.
  • a direct current that is, a direct current from the substrate 10 to the lithium ion secondary battery 1 through the base layer 20, the positive electrode layer 30, the solid electrolyte layer 40, the holding layer 50, the diffusion prevention layer 60, and the negative electrode current collector layer 70, Charging current flows.
  • lithium ions constituting the positive electrode active material in the positive electrode layer 30 move to the holding layer 50 via the solid electrolyte layer 40. That is, in the charging operation, the lithium ions move in the thickness direction of the lithium ion secondary battery 1 (upward in FIG. 1).
  • the lithium ions that have moved from the positive electrode layer 30 side to the holding layer 50 side are alloyed with the noble metal (platinum in this example) constituting the holding layer 50 (solid solution, formation of an intermetallic compound, or eutectic). I do.
  • the noble metal platinum in this example
  • the diffusion prevention layer 60 of the present embodiment is made of a metal or an alloy having an amorphous structure, and has a significantly smaller number of grain boundaries than the holding layer 50 having a polycrystalline structure. ing. For this reason, the lithium ions that have reached the boundary between the holding layer 50 and the diffusion prevention layer 60 are less likely to enter the diffusion prevention layer 60, and thus maintain the state held in the holding layer 50.
  • the lithium ions moved from the positive electrode layer 30 to the holding layer 50 are held by the holding layer 50.
  • the lithium ions that have moved to the holding layer 50 are held by the holding layer 50 by alloying with platinum or by precipitating metallic lithium in the platinum. Therefore, in this state, it can be said that a negative electrode layer made of lithium is formed inside the holding layer 50.
  • lithium ions constituting the negative electrode existing inside the holding layer 50 move along the thickness direction (downward in FIG. 1) to the positive electrode layer 30 via the solid electrolyte layer 40, and again 30.
  • the alloy of lithium and platinum is dealloyed (dissolution of metallic lithium when metallic lithium is precipitated) with the release of lithium. Then, as a result of dealloying in the holding layer 50, the holding layer 50 is made porous, and becomes a porous portion in which a large number of holes are formed.
  • the porous portion obtained in this manner is substantially composed of a noble metal (platinum in this example).
  • the solid electrolyte layer 40 has a two-layer structure of the first solid electrolyte layer 41 and the second solid electrolyte layer 42, but is not limited to this.
  • the side in contact with the positive electrode layer 30 is set as a layer having a low nitrogen concentration (a layer having a composition close to Li 3 PO 4 ) and held.
  • the side in contact with the layer 50 may be a layer having a high nitrogen concentration (a layer having a composition of LiPON). In other words, there may not be a clear boundary between the first solid electrolyte layer 41 and the second solid electrolyte layer 42.
  • the nitrogen concentration in the chamber may be gradually increased in the solid electrolyte forming step shown in step 40 of FIG.
  • the concentration of nitrogen on the side of the solid electrolyte layer 40 that contacts the positive electrode layer 30 may not be 0%, but is preferably 0%.
  • the base layer 20, the positive electrode layer 30, the solid electrolyte layer 40, the holding layer 50, the diffusion preventing layer 60, and the negative electrode current collector layer 70 are stacked on the substrate 10 in this order, so that lithium
  • the basic structure of the ion secondary battery 1 was formed. That is, a configuration is adopted in which the positive electrode layer 30 is arranged on the side closer to the substrate 10 and the holding layer 50 is arranged on the side farther from the substrate 10.
  • the present invention is not limited to this, and a configuration in which the holding layer 50 is arranged on the side closer to the substrate 10 and the positive electrode layer 30 is arranged on the side farther from the substrate 10 may be adopted.
  • the stacking order of each layer on the substrate 10 is opposite to that described above except for the base layer 20.
  • the holding layer 50 is made of a noble metal, but the present invention is not limited to this.
  • a noble metal a platinum group element (Ru, Rh, Pd, Os, Ir, Pt) or gold (Au) or an alloy thereof) is used.
  • the holding layer 50 can be configured.
  • the present inventor produced ten types (Examples and Comparative Examples) of lithium ion secondary batteries 1 and evaluated the structures and various electrical characteristics of each.
  • the lithium ion secondary battery 1 having the structure shown in FIG. 1 described in the above embodiment was used. That is, in the example, the base layer 20, the positive electrode layer 30, the first solid electrolyte layer 41, the second solid electrolyte layer 42, the holding layer 50, the diffusion prevention layer 60, and the negative electrode current collector layer 70 are formed on the substrate 10 in this order. The lithium ion secondary battery 1 laminated by the above was used.
  • FIG. 3 is a diagram showing a cross-sectional configuration of the lithium ion secondary battery 1 of the first comparative example.
  • the lithium ion secondary battery 1 of the first comparative example also has a structure in which a plurality of layers are stacked as described in the embodiment, that is, similarly to the lithium ion secondary battery 1 of the example.
  • the lithium ion secondary battery 1 of the first comparative example shown in FIG. 3 has a base layer 20, a positive electrode layer 30, and a solid electrolyte layer 40 on a substrate 10, similarly to the lithium ion secondary battery 1 of the embodiment shown in FIG. , A holding layer 50, a diffusion prevention layer 60 and a negative electrode current collector layer 70 are laminated in this order.
  • the solid electrolyte layer 40 of the first comparative example includes only the second solid electrolyte layer 42 that is stacked on the positive electrode layer 30 and to be stacked with the holding layer 50, and includes the first solid electrolyte layer 41. Not in the embodiment.
  • the solid electrolyte layer 40 in the lithium ion secondary battery 1 of the first comparative example is the same as the embodiment in that the solid electrolyte layer 40 includes the second solid electrolyte layer 42, but does not include the first solid electrolyte layer 41. This is different from the embodiment.
  • the first comparative example is different from the first comparative example in that the second solid electrolyte layer 42 is stacked on the positive electrode layer 30.
  • FIG. 4 is a diagram showing a cross-sectional configuration of the lithium ion secondary battery 1 of the second comparative example.
  • the lithium ion secondary battery 1 of the second comparative example shown in FIG. 4 also has an underlayer 20, a positive electrode layer 30, and a solid electrolyte layer 40 on a substrate 10, similarly to the lithium ion secondary battery 1 of the embodiment shown in FIG. , A holding layer 50, a diffusion prevention layer 60 and a negative electrode current collector layer 70 are laminated in this order.
  • the solid electrolyte layer 40 of the second comparative example is stacked on the second solid electrolyte layer 42 and the second solid electrolyte layer 42 that are stacked on the positive electrode layer 30, and is an object to be stacked on the holding layer 50. It differs from the embodiment in that it has a first solid electrolyte layer 41. That is, although the solid electrolyte layer 40 in the lithium ion secondary battery 1 of the second comparative example includes the first solid electrolyte layer 41 and the second solid electrolyte layer 42, the solid electrolyte layer 40 is the same as the embodiment, The difference from the embodiment is that the order is reversed. Further, as a result, in the second comparative example, the second solid electrolyte layer 42 is stacked on the positive electrode layer 30 and the holding layer 50 is stacked on the first solid electrolyte layer 41. different.
  • FIG. 5 is a diagram showing a cross-sectional configuration of the lithium ion secondary battery 1 of the third comparative example.
  • the lithium ion secondary battery 1 of the third comparative example shown in FIG. 5 also has an underlayer 20, a positive electrode layer 30, and a solid electrolyte layer 40 on a substrate 10, similarly to the lithium ion secondary battery 1 of the embodiment shown in FIG. , A holding layer 50, a diffusion prevention layer 60 and a negative electrode current collector layer 70 are laminated in this order.
  • the solid electrolyte layer 40 of the third comparative example includes a second solid electrolyte layer 42 stacked on the positive electrode layer 30, a first solid electrolyte layer 41 stacked on the second solid electrolyte layer 42, and a first solid electrolyte layer 41.
  • the second embodiment is different from the first embodiment in that the second embodiment is provided with a second solid electrolyte layer 42 which is laminated on the solid electrolyte layer 41 and on which the holding layer 50 is laminated.
  • the solid electrolyte layer 40 in the lithium ion secondary battery 1 of the third comparative example includes the first solid electrolyte layer 41 and the second solid electrolyte layer 42, the solid electrolyte layer 40 corresponds to the embodiment, This embodiment is different from the embodiment in that two solid electrolyte layers 42 are provided and one first solid electrolyte layer 41 is sandwiched between these two second solid electrolyte layers 42.
  • Table 1 shows a configuration of the lithium ion secondary battery 1 according to the example.
  • Table 1 shows the relationship between the name of each layer constituting the lithium ion secondary battery 1 and the material constituting each layer and its thickness. This is the same in Tables 2 to 4 described later.
  • three types of lithium ion secondary batteries 1 having different thicknesses of the first solid electrolyte layer 41 were prepared. Hereinafter, these are referred to as Examples 1 to 3, respectively.
  • Example 1 In Example 1, stainless steel (more specifically, SUS316L) was used as the substrate 10. The thickness of the substrate 10 was 0.1 mm.
  • the underlayer 20 made of LiNiO 2 was formed by using the sputtering method. The thickness of the underlayer 20 was 200 nm.
  • the positive electrode layer 30 made of LiNiO 2 and Li 3 PO 4 was formed by using the sputtering method. The thickness of the positive electrode layer 30 was 800 nm.
  • the ratio (molar ratio) between LiNiO 2 and Li 3 PO 4 in the positive electrode layer 30 was 73:27.
  • Example 1 the first solid electrolyte layer 41 made of Li 3 PO 4 was formed by using the sputtering method. The thickness of the first solid electrolyte layer 41 was 11 nm.
  • the second solid electrolyte layer 42 made of LiPON was formed by using the sputtering method. The thickness of the second solid electrolyte layer 42 was 1980 nm.
  • the holding layer 50 made of Pt was formed by using the sputtering method. The thickness of the holding layer 50 was 30 nm.
  • the diffusion preventing layer 60 made of CrTi was formed by using the sputtering method. The thickness of the diffusion prevention layer 60 was 200 nm.
  • Example 1 the negative electrode current collector layer 70 made of Pt was formed by using the sputtering method.
  • the thickness of the negative electrode current collector layer 70 was 30 nm.
  • the basic structure of the lithium ion secondary battery 1 thus obtained was initially charged and discharged to obtain the lithium ion secondary battery 1. Note that the thickness of the holding layer 50 was increased from the initial value of 30 nm by performing the initial charge / discharge.
  • Example 2 In Example 2, the same structure as in Example 1 was adopted except that the thickness of the first solid electrolyte layer 41 was set to 22 nm.
  • Example 3 In Example 3, the same structure as in Example 1 was adopted except that the thickness of the first solid electrolyte layer 41 was set to 33 nm.
  • Table 2 shows a configuration of the lithium ion secondary battery 1 according to the first comparative example.
  • one type of lithium ion secondary battery 1 was prepared as a first comparative example.
  • the same structure as in Example 1 was adopted except that the first solid electrolyte layer 41 was not provided, in other words, the thickness of the first solid electrolyte layer 41 was set to 0 nm.
  • Table 3 shows a configuration of the lithium ion secondary battery 1 according to the second comparative example.
  • three types of lithium ion secondary batteries 1 having different thicknesses of the first solid electrolyte layer 41 were prepared as a second comparative example.
  • these are referred to as a second comparative example (1) to a second comparative example (3), respectively.
  • Table 4 shows a configuration of the lithium ion secondary battery 1 according to the third comparative example.
  • a third comparative example three types of lithium ion secondary batteries 1 having different thicknesses of the first solid electrolyte layer 41 were prepared. Hereinafter, these are referred to as third comparative example (1) to third comparative example (3), respectively.
  • the third comparative example (1) has the same structure as that of the first embodiment except that the solid electrolyte layer 40 has a three-layer structure of a second solid electrolyte layer 42, a first solid electrolyte layer 41, and a second solid electrolyte layer 42. It was adopted.
  • one of the second solid electrolyte layers 42 stacked on the positive electrode layer 30 has a thickness of 1000 nm, and the other second solid electrolyte layer 42 to be stacked on the holding layer 50. was also 1000 nm thick.
  • the total thickness (2000 nm) of the second solid electrolyte layer 42 was made substantially the same as the thickness (1980 nm) in Examples 1 to 3, the first comparative example, and the second comparative example.
  • the thickness of the first solid electrolyte layer 41 sandwiched between the two second solid electrolyte layers 42 was set to 11 nm, which is the same as in the first embodiment.
  • Crystal structure First, the crystal structure will be described. The inventor measured the electron diffraction pattern of each of the lithium ion secondary batteries 1 of Examples and Comparative Examples, and found that the crystal structure (crystallized, amorphous) of each layer constituting the lithium ion secondary battery 1 was measured. Quality).
  • the substrate 10, the holding layer 50, and the negative electrode current collector layer 70 were each crystallized.
  • the underlayer 20, the first solid electrolyte layer 41, the second solid electrolyte layer 42, and the diffusion prevention layer 60 were amorphous.
  • the positive electrode layer 30 a crystallized region and an amorphous region were mixed, and a crystallized region was scattered with respect to the amorphous region.
  • each layer constituting the lithium ion secondary battery 1 of the first comparative example constitutes the lithium ion secondary battery 1 of the above-described Examples 1 to 3, except that the first solid electrolyte layer 41 does not exist. It had the same crystal structure as each layer.
  • the lithium ion secondary batteries 1 of the second comparative example (1) to the second comparative example (3) and the third comparative example 1 to the third comparative example (3) also have the lithium ion secondary batteries 1 of the first to third examples.
  • the crystal structure was the same as each layer constituting the ion secondary battery 1.
  • the discharge capacity represents the amount of electricity discharged from the lithium ion secondary battery 1 from the start of use (start of discharge) after the completion of charging to the end of use (end of discharge), and the discharge current (discharge current) It can be obtained by multiplying the time until the discharge end voltage is reached. In this case, the larger the value of the discharge capacity, the better.
  • the charge / discharge characteristics of each lithium ion secondary battery 1 of each of the examples and comparative examples were measured, and the discharge capacity was evaluated based on the results.
  • a charge and discharge device HJ1020mSD8 manufactured by Hokuto Denko KK was used as a device for measuring the charge and discharge characteristics.
  • the current during charging (charging current) and the current during discharging (discharge current) were 0.6 (mA) and 20 (mA), respectively.
  • the former is described as “$ 0.6 mA” and the latter is described as “$ 20 mA”.
  • the capacity retention ratio is a percentage of the capacity of the lithium ion secondary battery 1 at the time when a predetermined period has elapsed with respect to the initial capacity after the completion of charging. In this case, the higher the value of the capacity retention ratio, the better, and the value is 100% at the maximum.
  • the capacity retention rate after full charge and after 3 hours was measured. In Table 5, it was described as "$ 3 hours later".
  • the internal resistance is an electric resistance existing inside the lithium ion secondary battery 1. In this case, the smaller the value of the internal resistance, the better.
  • the internal resistance when a discharge current of 20 (mA) was passed was measured. In Table 5, it is described as “$ 20 mA”.
  • Example had a smaller discharge capacity value at 0.6 mA than the first comparative example. Further, in the example, the value of the discharge capacity at 20 mA was larger than in the first comparative example. Further, the example had a higher capacity retention ratio than the first comparative example. In the example, the value of the internal resistance was smaller than in the first comparative example.
  • Example and a second comparative example will be compared.
  • the example had a smaller discharge capacity value at 0.6 mA than the second comparative example. Further, in the example, the value of the discharge capacity at 20 mA was larger than that in the second comparative example. Further, the example had a higher capacity retention ratio than the second comparative example. In the example, the value of the internal resistance was smaller than in the second comparative example.
  • Example 1 Comparative of Example 1, Example 2, and Example 3
  • Example 2 and Example 3 are compared.
  • Example 2 [Comparison between Example 1 and Example 2] Now, a comparison between the first embodiment and the second embodiment will be made. First, in Example 2, the value of the discharge capacity at 0.6 mA was larger than that in Example 1 (about 107%). Further, in Example 2, the value of the discharge capacity at 20 mA was smaller than that in Example 1 (about 93%). Furthermore, Example 2 had a higher capacity retention ratio than Example 1 (about 101%). In Example 2, the value of the internal resistance was larger than that in Example 1 (about 159%).
  • Example 3 the value of the discharge capacity at 0.6 mA was smaller than that in Example 2 (about 99%).
  • Example 3 had a smaller discharge capacity value at 20 mA than Example 2 (about 94%).
  • Example 3 had a higher capacity retention ratio than Example 2 (about 101%).
  • the value of the internal resistance was larger than that in Example 2 (about 107%).
  • the discharge capacity at 0.6 mA although there is some magnitude relationship, in the example and all of the first to third comparative examples, the discharge capacity was on the order of 500 ⁇ Ah (third example (1)). The same applies hereinafter).
  • the discharge capacity at 20 mA was more than one order of magnitude larger than the first comparative example to the third comparative example and was on the order of 100 ⁇ A (actually 140 ⁇ A or more).
  • the capacity retention ratio of the example was higher than that of the first comparative example to the third comparative example, and exceeded 98%.
  • the capacity retention ratio was 100%, which is the highest value.
  • the capacity retention ratio was 98.6%, which was higher than that in the first comparative example (98%).
  • the example was smaller than the first to third examples and less than 30 ⁇ .
  • the internal resistance was 17 ⁇ , which was the lowest value.
  • the solid electrolyte layer 40 has a two-layer structure of the first solid electrolyte layer 41 made of Li 3 PO 4 and the second solid electrolyte layer 42 made of LiPON, and the first solid electrolyte layer 41 is provided on the positive electrode layer 30 side. It can be seen that by arranging the second solid electrolyte layers 42 on the holding layer 50 side, respectively, it is possible to suppress a decrease in the capacity retention ratio. It can also be seen that the adoption of such a structure can suppress an increase in internal resistance.
  • SYMBOLS 1 lithium ion secondary battery, 10 ... board

Abstract

Cette invention concerne une batterie rechargeable au lithium-ion (1) configurée, par stratification dans cet ordre, par : un substrat (10) qui comprend de l'acier inoxydable et qui sert de couche de collecteur de courant d'électrode positive ; une couche de masse (20) à base de LiNiO2 ; une couche d'électrode positive (30) configurée par une électrode positive en matériau composite qui contient du LiNiO2 et du Li3PO4 ; une première couche d'électrolyte solide (41) à base de Li3PO4 ; une seconde couche d'électrolyte solide (42) à base de LiPON où une partie de l'oxygène dans le Li3PO4 est substituée par de l'azote ; une couche support (50) à base de de Pt ; une couche de prévention de diffusion (60) à base de CrTi ; et une couche de collecteur de courant d'électrode négative (70) à base de Pt. Du fait de cette configuration, dans la batterie rechargeable au lithium-Ion qui utilise du LiPON en tant qu'électrolyte solide, une baisse du taux de rétention de la capacité est supprimée.
PCT/JP2019/014775 2018-07-10 2019-04-03 Batterie rechargeable au lithium-ion WO2020012734A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004228029A (ja) * 2003-01-27 2004-08-12 Matsushita Electric Ind Co Ltd 電気化学素子とその製法およびその製造装置
JP2013097969A (ja) * 2011-10-31 2013-05-20 Toyota Motor Corp 全固体電池用電極、及び当該電極を含む全固体電池
JP2016219130A (ja) * 2015-05-15 2016-12-22 セイコーエプソン株式会社 固体電解質電池、電極複合体、複合固体電解質および固体電解質電池の製造方法
JP2017152324A (ja) * 2016-02-26 2017-08-31 富士通株式会社 全固体電池

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004228029A (ja) * 2003-01-27 2004-08-12 Matsushita Electric Ind Co Ltd 電気化学素子とその製法およびその製造装置
JP2013097969A (ja) * 2011-10-31 2013-05-20 Toyota Motor Corp 全固体電池用電極、及び当該電極を含む全固体電池
JP2016219130A (ja) * 2015-05-15 2016-12-22 セイコーエプソン株式会社 固体電解質電池、電極複合体、複合固体電解質および固体電解質電池の製造方法
JP2017152324A (ja) * 2016-02-26 2017-08-31 富士通株式会社 全固体電池

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