WO2020039609A1 - Negative electrode for lithium battery, method for manufacturing same, and lithium battery - Google Patents
Negative electrode for lithium battery, method for manufacturing same, and lithium battery Download PDFInfo
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- WO2020039609A1 WO2020039609A1 PCT/JP2019/000587 JP2019000587W WO2020039609A1 WO 2020039609 A1 WO2020039609 A1 WO 2020039609A1 JP 2019000587 W JP2019000587 W JP 2019000587W WO 2020039609 A1 WO2020039609 A1 WO 2020039609A1
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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- 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 negative electrode for a lithium battery, a method for producing the same, and a lithium battery.
- lithium batteries have a high terminal voltage and a high energy density, and as a device for storing or generating electric energy, main batteries such as portable electronic devices, electric vehicles, and mobile communication devices. Its use is expanding.
- a lithium battery is basically composed of a battery member such as a separator, if necessary, in addition to a positive electrode, a negative electrode, and an electrolyte, and is used as a primary battery or a secondary battery.
- a battery member such as a separator
- electrolyte a battery member that moves from the positive electrode to the negative electrode to accumulate charge
- lithium ions move from the negative electrode to the positive electrode.
- a lithium battery is a lithium metal battery or a lithium air battery using metal lithium as a negative electrode active material of a negative electrode, a lithium ion battery using graphite or silicon as a negative electrode, a lithium oxide or the like as a positive electrode, or the like.
- metal lithium as a negative electrode active material of a negative electrode
- lithium ion battery using graphite or silicon as a negative electrode
- lithium oxide or the like as a positive electrode, or the like.
- lithium ion secondary batteries are widely used as a negative electrode active material because carbon materials such as graphite capable of inserting and extracting lithium ions exhibit relatively high capacity and good cycle characteristics.
- carbon materials such as graphite capable of inserting and extracting lithium ions exhibit relatively high capacity and good cycle characteristics.
- a negative electrode active material capable of further increasing the capacity has been demanded.
- carbon nanotubes extended from a conductive composite material are fixed as a structure applied as a whole or a part of a current conductor and an electrode for an electrochemical power device such as a conductive battery, a supercapacitor, and a fuel cell.
- An example is shown in which such a structure is applied as an electrode of a lithium battery (for example, see Patent Document 2).
- a negative electrode for a lithium battery including a conductive material layer having a three-dimensional surface structure in which a carbon nanotube is extended (extended) from the surface, metal lithium as a negative electrode active material is deposited on the carbon nanotube.
- Patent Literature 3 does not disclose a concept of effectively preventing such a decrease in charge / discharge capacity.
- the present invention has been made in view of such circumstances, and has a three-dimensional surface structure including an underlayer, and a plurality of nanocarbon materials extending from the surface of the underlayer, and as a negative electrode.
- lithium metal or a negative electrode for a lithium battery in the case of using graphite or silicon as the negative electrode, lithium capable of effectively preventing a decrease in charge / discharge capacity even when charging and discharging of the lithium battery is repeated. It is an object to provide a negative electrode for a battery, a method for producing the same, and a lithium battery.
- the gist configuration of the present invention is as follows.
- the intermediate layer is made of a metal or an alloy capable of forming an alloy with lithium.
- the material forming the surface layer is graphite or silicon.
- the intermediate layer includes one or more metals selected from Al, Zn, Cr, Fe, Ni, Sn, Pb, Cu, Ag, Pt, Au, In, Pd, and Mg.
- the intermediate layer is made of a metal of Sn, Al, Au, Mg, Ag or Zn, or an alloy of Cu and Sn or Ni.
- the thickness of the intermediate layer is in the range of 0.01 ⁇ m or more and 3 ⁇ m or less.
- the nanocarbon material includes a carbon nanotube.
- a base layer made of a metal or an alloy is fixed on the surface of the substrate by an electrolytic plating method, and at least one surface of the base layer is fixed to the base layer. Forming a structure having a plurality of nanocarbon materials extending therefrom; and forming at least one surface of the underlayer constituting the structure, and extending the plurality of nanocarbon materials extending from the surface.
- the present invention it is possible to provide a negative electrode for a lithium battery, a method for manufacturing the same, and a lithium battery that can effectively prevent a decrease in charge / discharge capacity even when charge / discharge of the lithium battery is repeated.
- FIG. 3 is a cross-sectional view schematically illustrating a part of a substrate having a structure including an underlayer to which a plurality of carbon nanotubes are fixed. It is the schematic which shows typically an example of the composite plating apparatus used when forming the base layer in which the carbon nanotube was fixed on the board
- FIG. 4 is a cross-sectional view schematically showing a part of an underlayer and an intermediate layer formed on carbon nanotubes. It is the schematic which shows the plating apparatus used for formation of an intermediate
- FIG. 9 is a cross-sectional view schematically illustrating a state where a part of the surface of the intermediate layer is brought into contact with molten lithium in a third stage of the surface layer forming step.
- FIG. 9 is a cross-sectional view schematically showing a state where the substrate is moved along the support from the state shown in FIG. 8 in a third stage of the surface layer forming step.
- FIG. 10 is a cross-sectional view schematically showing a state where the substrate is further moved from the state shown in FIG. 9 to form a surface layer on the intermediate layer in the third stage of the surface layer forming step.
- FIG. 2 is a cross-sectional view schematically illustrating a lithium metal battery according to a first embodiment, which is manufactured using the negative electrode illustrated in FIG. 1. It is sectional drawing which shows the lithium air battery which concerns on 2nd embodiment typically. It is sectional drawing which shows the lithium ion battery which concerns on 3rd embodiment typically. It is sectional drawing which shows typically the lithium solid battery which concerns on 4th Embodiment.
- FIG. 5 is a diagram plotting the relationship between the number of cycles and the charge / discharge capacity retention rate when a cycle test in which charge / discharge is repeated is performed for each of the manufactured lithium secondary batteries of Example 1 and Comparative Example 1.
- the present inventors have used lithium metal as a negative electrode active material of a negative electrode, lithium metal batteries and lithium air batteries, and graphite or silicon as a negative electrode, using lithium oxide and the like as a positive electrode, lithium ion batteries and the like.
- the charge / discharge capacity was correspondingly reduced.
- various studies were made on measures to prevent the decrease in charge / discharge capacity.
- FIG. 1 is a diagram schematically illustrating a cross-sectional configuration of a negative electrode 10 (hereinafter, also simply referred to as “negative electrode 10”) used in a lithium metal battery included in the lithium battery according to the present embodiment.
- the negative electrode 10 shown in FIG. 1 includes a substrate 20, a base layer 12 made of a metal or an alloy formed on the surface of the substrate 20, and fixed to the base layer 12 and extending from at least one surface of the base layer 12.
- It has a laminated body 16 configured to include.
- the laminate 16 has a three-dimensional surface structure, not a smooth surface.
- the negative electrode active material is lithium.
- the structure 13 shown in FIG. 1 includes a carbon nanotube 11 as a nanocarbon material and an underlayer 12 in which at least a part of the carbon nanotube 11 is embedded and fixed, and functions as a negative electrode current collector. It is.
- the carbon nanotubes 11 are fixed to the underlayer 12 and extend from the surface 12a of the underlayer 12.
- a carbon nanotube is used as an example of a nanocarbon material.
- the present invention is not limited to a carbon nanotube, and the nanocarbon material is not limited to a carbon nanofiber or a cellulose nanofiber.
- a negative electrode for a lithium battery including a carbon material is also included in the present invention.
- the stacked body 16, particularly, the carbon nanotubes 11 are shown larger than the actual dimensions, and are different from the actual dimensions.
- the underlayer 12 covers and embeds a part including the one end 11 a of the carbon nanotube 11, and the other end 11 b of the carbon nanotube 11 extends from the surface 12 a of the underlayer 12.
- An embodiment is shown.
- the underlayer 12 embeds and fixes a substantially central portion in the longitudinal direction of the carbon nanotube 11, and both end portions 11 a and 11 b of the carbon nanotube 11 have surfaces (first surface) 12 a and 11 a of the underlayer 12. Each may extend from the back surface (second surface) 12b.
- the carbon nanotube 11 is a carbon material having a shape obtained by winding graphite in a tubular shape, and has a diameter of, for example, several nm or more and 100 nm or less, and a length of several nm or more and 1 mm or less.
- the carbon nanotube 11 may have either a single-layer structure or a multi-layer structure.
- the nanocarbon material not only the carbon nanotube 11 alone, but also a carbon nanofiber having a fiber diameter of about 100 nm or more and about 1 ⁇ m or less may be included.
- the carbon nanotubes 11 are partially embedded in the underlayer 12 and extend from at least the surface 12 a of the underlayer 12.
- the underlayer 12 is disposed as an underlayer for forming the intermediate layer 14.
- the base layer 12 includes a conductive metal such as copper, nickel, zinc, aluminum, gold, and silver, and an alloy containing these metals or other metals. Among these metal components, the base layer 12 is preferably made of copper in consideration of the material cost and conductivity.
- the base layer 12 embeds and fixes a part of the carbon nanotubes 11, and extends the surface 12 a of the base layer 12 and the plurality of carbon nanotubes 11 extending from the surface 12 a.
- a middle layer 14 and a surface layer 15 as a negative electrode active material made of metallic lithium are sequentially deposited to form a laminate 16.
- the thickness of the underlayer 12 is preferably 3 ⁇ m or more and 5 mm or less.
- the carbon nanotubes 11 are configured to be embedded in the underlayer 12, and extend from at least the surface 12 a of the underlayer 12, so that the surface 12 a of the underlayer 12 is , Not a smooth surface, but a three-dimensional surface structure. Therefore, the surface area of the surface 12a of the underlayer 12 is larger than that of the smooth surface.
- the underlayer 12 having the surface 12a on which the carbon nanotubes 11 extend is configured as a negative electrode current collector.
- the layer 14 and the surface layer 15 are formed.
- the surface density of the carbon nanotubes 11 on the surface 12a of the underlying layer 12 is not particularly limited, 0.1 mg / cm 2 or more is preferably about 10 mg / cm 2 or less.
- the areal density is within the above range, the growth of dendrites generated on the surface 15a of the surface layer 15 during charging and discharging of the lithium battery can be sufficiently suppressed, and the safety of the battery is improved.
- the carbon nanotubes 11 may extend substantially vertically or obliquely from the surface 12a.
- the nanotubes 11 may extend so as to be entangled with each other.
- the carbon nanotubes 11 are not limited to the mode in which the carbon nanotubes 11 extend outward in a state where they are arranged at regular intervals on the surface 12a of the underlayer 12, but extend in a state where they are arranged at random intervals. It may be a mode of doing.
- the intermediate layer 14 is disposed between the underlayer 12 made of a metal or an alloy and the surface layer 15 made of the negative electrode active material (metal lithium), and between the carbon nanotube 11 and the surface layer 15. Composed of different metals or alloys.
- metal lithium negative electrode active material
- the intermediate layer 14 is made of a metal or an alloy capable of forming an alloy with lithium, a decrease in charge / discharge capacity can be more effectively prevented even when charging and discharging of the lithium battery are repeated.
- the intermediate layer 14 in particular, one kind of metal selected from Al, Zn, Cr, Fe, Ni, Sn, Pb, Cu, Ag, Pt, Au, In, Pd and Mg, or an alloy containing one or more kinds By using, it is possible to effectively prevent a decrease in charge / discharge capacity even when charge / discharge of a lithium battery is repeated.
- the intermediate layer 14 is formed of a metal of Sn, Al, Au, Mg, Ag, or Zn, or an alloy of Cu and Sn or Ni, the charge / discharge capacity is reduced even if the charge / discharge of the lithium battery is repeated. Can be further enhanced.
- the intermediate layer 14 is made of Sn as described later, the effect of preventing a decrease in charge / discharge capacity can be further enhanced even if charge / discharge of the lithium battery is repeated.
- the thickness of the intermediate layer 14 is preferably 0.01 ⁇ m or more and 3 mm or less.
- the thickness of the intermediate layer 14 is 0.01 ⁇ m or more and 3 mm or less, at the time of depositing metallic lithium by a lithium metal deposition method described later, the metal or alloy component constituting the intermediate layer 14 and the deposited metallic lithium are alloyed. It can be considered that by forming, metal lithium can be deposited relatively uniformly and deterioration of cycle characteristics can be suppressed.
- a negative electrode active material made of metallic lithium is used as the surface layer 15, and the surface layer 15 is formed of a layer on which metallic lithium is deposited.
- an intermediate layer 14 is formed on a surface 12 a of an underlayer 12 and on a carbon nanotube 11 extending from the surface 12 a of the underlayer 12.
- a negative electrode active material made of lithium is deposited to form a surface layer 15.
- the surface layer 15 of metallic lithium forms a three-dimensional structure in which the carbon nanotubes 11 extend from the surface 12a of the underlayer 12, the surface 15a of the surface layer 15, that is, the deposited metallic lithium
- the surface is not a smooth surface but a surface having a three-dimensional surface structure.
- the deposition amount of metallic lithium constituting the surface layer 15 is not particularly limited, but is 0.01 mg / cm 2 or more and 5 mg / cm 2 from the viewpoint of preventing deterioration of battery characteristics, improving productivity, and suppressing dendrite growth. It is preferably about 2 or less. Further, when the deposition amount of metallic lithium is 0.01 mg / cm 2 or more, the amount of metallic lithium as the negative electrode active material is sufficient, and the battery characteristics are good. When the deposition amount of metallic lithium is 5.00 mg / cm 2 or less, productivity and suppression of dendrite growth can be effectively achieved.
- the surface layer 15 of metallic lithium only needs to be deposited to a certain thickness, and is preferably deposited over the entire surface of the carbon nanotubes 11 and the underlayer 12.
- the deposition state of the surface layer 15 can be changed within a range that does not affect the battery characteristics. Partially deposited state is acceptable.
- the substrate 20 is preferably made of a metal or an alloy having high conductivity.
- substrate 20 comprises a metal or alloy selected from the group of copper, copper alloy, nickel, nickel alloy, zinc, zinc alloy, aluminum, aluminum alloy, gold, gold alloy, silver, silver alloy, and stainless steel.
- the shape may be a foil, a film, a plate, or the like.
- the substrate 20 may include various additives such as a conductive polymer depending on required characteristics.
- the thickness of the substrate 20 is preferably in the range of 3 ⁇ m or more and 5 mm or less from the viewpoint of excellent operability in manufacturing the negative electrode 10 for a lithium battery.
- the substrate 20 the base layer 12 made of a metal or an alloy, formed on the substrate 20, and at least one of the base layers 12 fixed to the base layer 12.
- An intermediate layer made of a metal or an alloy different from the underlayer 12 is provided between the structure 13 having the plurality of carbon nanotubes 11 extending from the surface 12a and the surface layer 15 functioning as a negative electrode active material of the negative electrode 10 for a lithium battery. Since the layer 14 is provided, a decrease in the charge / discharge capacity can be effectively prevented even when the charge / discharge of the lithium battery is repeated.
- an underlayer 12 made of a metal or an alloy and at least one surface of the underlayer 12 fixed to the underlayer 12 are provided on the surface of the substrate 20.
- Forming a structure 13 having a plurality of carbon nanotubes 11 extending from the surface, one surface 12a of the underlayer 12, and the surface of the extending portion of the plurality of carbon nanotubes 11 extending from the surface 12a is performed.
- the base layer 12 and a part including one end 11 a are buried and fixed in the base layer 12, and project from the surface 12 a of the base layer 12. Then, a plurality of carbon nanotubes 11 extending to form a structure 13 having the underlayer 12 and the carbon nanotubes 11 are formed.
- the method for manufacturing the structure 13 is not particularly limited, and includes, for example, an electrolytic plating (composite plating) method in which carbon nanotubes are dispersed in an electrolytic solution.
- FIG. 3 shows a composite plating apparatus used to form, on a substrate 20, an underlayer 12 to which an underlayer 12 and a plurality of carbon nanotubes 11 (see FIG. 2) extending from the surface of the underlayer 12 are fixed. It is the schematic which shows an example of 30 typically.
- the composite plating apparatus 30 includes a pretreatment tank 21, an electrolytic plating treatment tank 23, a post-treatment tank 25, a cathode power supply roller 27, and a nip roller 28.
- the long sheet-shaped substrate 20 made of a metal foil or the like is transported in a horizontal direction by a cathode power supply roller 27 and a nip roller 28, and is first subjected to a cleaning treatment in a pretreatment tank 21, and then to an electrolytic plating treatment tank 23. Electrolytic plating (composite plating) is performed, and then rust prevention is performed in the post-treatment tank 25.
- the structure 13 including the underlayer 12 and the plurality of carbon nanotubes 11 (see FIG. 2) extending from the surface of the underlayer 12 is formed on the substrate 20.
- the pretreatment tank 21 is a treatment tank that performs a pretreatment such as a degreasing treatment or an pickling treatment on the substrate 20, and contains a chemical solution (a pretreatment liquid 22) for performing the pretreatment.
- the electrolytic plating tank 23 contains the electrolytic plating solution 24 and has anode electrodes 23a and 23b on the upper and lower parts, respectively.
- cuprous sulfate (CuSO 4 .5H 2 O) of about 20 g / L to 300 g / L is used as the electrolytic plating solution.
- An electrolytic plating solution of copper sulfate obtained by mixing sulfuric acid (H 2 SO 4 ) of about 5 g / L or more and about 50 g / L or less can be used.
- the content of the carbon nanotubes in the electrolytic plating solution 24 is, for example, about 1% by mass or more and 50% by mass or less. Note that the composition of the electrolytic plating solution 24 and the content of the carbon nanotubes are not limited to these, but are appropriately adjusted according to required characteristics. Further, the electrolytic plating solution 24 may contain various additives such as chloride ions, polyethers, leveling agents, and surfactants, if necessary.
- both of the anode electrodes 23 a and 23 b are energized to perform electrolytic plating on both sides of the substrate 20 that is being transported in the horizontal direction, so that the base layer 12 that is an electrolytic plating film is
- the carbon nanotubes 11 can be fixed to the underlayer 12 while being formed thereon.
- only the anode electrode 23a or 23b located on the surface side of the substrate 20 on which the underlayer 12 is formed may be energized. Good.
- the post-treatment tank 25 is a treatment tank that performs post-treatment such as rust prevention treatment on the base layer 12 formed on the substrate 20 by electrolytic plating, and is a chemical solution for performing post-treatment (post-treatment liquid 26). Is housed.
- the intermediate layer forming step as shown in FIG. 4, at least one surface 12a of the underlayer 12 provided on the substrate 20 and the surface of the extending portion of the plurality of carbon nanotubes 11 extending from the surface 12a are provided on the underlayer.
- An intermediate layer 14 made of a metal or alloy different from 12 is formed.
- the method for forming the intermediate layer 14 is not particularly limited, and for example, an electrolytic plating method, an electroless plating method, or a vapor deposition method can be used.
- FIG. 5 shows that an intermediate layer 14 (see FIG. 4) is formed on at least one surface 12a of the base layer 12 and the surface of the extending portion of the plurality of carbon nanotubes 11 extending from the surface 12a by electrolytic plating.
- the plating apparatus 31 includes an electrolytic plating tank 33, a post-treatment tank 35, a cathode power supply roller 27, and a nip roller 28.
- the long sheet-like substrate 20 having the base layer 12 and the structure 13 including the plurality of carbon nanotubes 11 manufactured in the structure forming step is horizontally transferred by the cathode feeding roller 27 and the nip roller 28, First, after electrolytic plating is performed in the electrolytic plating tank 33, rust prevention processing is performed in the post-processing tank 35. In this way, in the intermediate layer forming step, the intermediate layer 14 (see FIG. 4) is provided on at least one surface 12a of the underlayer 12 and the surface of the extending portion of the plurality of carbon nanotubes 11 extending from the surface 12a. ) Is formed.
- the electrolytic plating tank 33 contains an electrolytic plating solution 34 and has anode electrodes 23a and 23b on the upper and lower parts, respectively.
- As the electrolytic plating solution 34 a solution containing metal ions that are reduced to the metal constituting the intermediate layer 14 is used.
- the electrolytic plating solution 34 for example, stannous sulfate (SnSO 4 ) of about 10 g / L or more and 100 g / L or less and sulfuric acid (H 2 SO 4 ) of about 50 g / L or more and 150 g / L or less are mixed. Can be used. Note that the composition of the electrolytic plating solution 34 is not limited to these, but is appropriately adjusted according to required characteristics. Further, the electrolytic plating solution 34 may contain various additives such as a surfactant, if necessary.
- SnSO 4 stannous sulfate
- H 2 SO 4 sulfuric acid
- the composition of the electrolytic plating solution 34 is not limited to these, but is appropriately adjusted according to required characteristics. Further, the electrolytic plating solution 34 may contain various additives such as a surfactant, if necessary.
- the electrolytic plating tank 33 by supplying electricity to both the anode electrodes 23 a and 23 b, electrolytic plating is performed on both surfaces of the substrate 20 having the structure 13, which is transported in the horizontal direction, to form an electrolytic plating film.
- the intermediate layer 14 can be formed on the surface 12 a of the underlayer 12 and on the carbon nanotubes 11. When the intermediate layer 14 is formed only on one surface of the substrate 20 having the structure 13, only the anode electrode 23a or 23b located on the surface side of the substrate 20 where the intermediate layer 14 is to be formed needs to be energized. I just need.
- the post-treatment tank 35 is a treatment tank for performing post-treatment such as rust prevention treatment on the intermediate layer 14 formed on the substrate 20 having the structure 13 by electrolytic plating, and is a chemical solution for performing the post-treatment. (Post-treatment liquid 36) is contained.
- the method for forming the surface layer 15 is not particularly limited.
- a lithium metal deposition method using electrolytic plating outside the cell a lithium metal deposition method using lithium contained in the positive electrode active material, a vapor deposition method inside the cell.
- a lithium metal deposition method by a method can be used.
- the molten lithium is pressed into contact with the surface of the intermediate layer 14 to form a molten lithium layer, and then cooled to form a molten lithium layer on the surface layer made of metallic lithium. It is possible to use a lithium metal deposition method by molten lithium pressing contact, which is carried out by solidification until the temperature reaches 15.
- the surface layer forming step using the lithium metal deposition method by molten lithium pressure contact is performed in an inert atmosphere such as argon or nitrogen. In this step, for example, the following two types of methods can be applied.
- the surface layer forming step has a first stage, a second stage, and a third stage.
- a metal lithium foil 42 is placed on a support 41.
- the support 41 is made of a metal component that is not alloyed with metallic lithium.
- the support 41 is made of metallic nickel.
- the thickness of the metal lithium foil 42 is preferably 0.1 ⁇ m or more and 100 ⁇ m or less from the viewpoint of the amount of lithium deposited on the surface layer 15 formed on the intermediate layer 14.
- the metallic lithium foil 42 is heated on the support 41 to generate molten lithium 43.
- the heating temperature of the metal lithium foil 42 is, for example, in the range of 200 ° C. or more and 500 ° C. or less.
- the support 41 and the metal lithium foil 42 are heated, and the metal lithium foil 42 placed on the support 41 is heated. Melts and changes to molten lithium 43.
- the metal lithium foil 42 on the support 41 is pressed by a roller member or the like so as to efficiently heat the metal lithium foil 42 by the hot plate 40, and the metal lithium foil 42 is adhered to the support 41. May be.
- the roller member is made of a metal component that does not alloy with lithium metal.
- the substrate 20 having the structure 13 is moved along the support 41 while the intermediate layer 14 is in contact with the molten lithium 43, whereby After forming the molten lithium layer 44 on the surface of the layer 14, the molten lithium layer 44 is cooled and solidified until the molten lithium layer 44 becomes the surface layer 15 made of lithium metal.
- the illustrated example shows a case where the surface layer 15 is formed by fixing the support 41 and moving the substrate 20 having the structure in which the intermediate layer 14 is formed on the structure 13 from right to left.
- the intermediate layer 14 of the substrate 20 is opposed to the support 41 so that the intermediate layer 14 formed on the surface of the underlayer 12 and the carbon nanotubes 11 is in contact with the molten lithium 43.
- the substrate 20 is pressed toward the support 41, and the molten lithium 43 is pressed into contact with (deposited on) the surfaces of the underlayer 12 and the carbon nanotubes 11.
- FIG. 9 when the substrate 20 is moved along the surface of the support 41 while the intermediate layer 14 and the molten lithium 43 (see FIG. 8) are in contact (deposit).
- the molten lithium 43 is deposited on the surface of the intermediate layer 14 from above the support 41, and a molten lithium layer 44 is formed on the surface of the intermediate layer 14.
- the second method includes a substrate supply step, a metal lithium foil supply step, and a laminate formation step.
- FIG. 11 is a schematic view schematically showing an example of a continuous laminate forming apparatus 50 in which the substrate supply step and the metal lithium foil supply step are simultaneously performed to continuously perform the laminate formation step.
- the laminated body continuous forming apparatus 50 includes a pair of heating members 51a and 51b and a film thickness adjusting member 57.
- the heating member 51a is formed of a cylindrical rotating member
- the heating member 51b is formed of a plate-shaped fixing member.
- the film thickness adjusting member 57 is located on the opposite side to the supply side of the metal lithium foil 53 with the heating member 51a interposed therebetween, and is provided at an upper position facing the surface of the intermediate layer 14.
- the lower surface 57a of the film thickness adjusting member 57 is not parallel to the surface of the underlayer 12 but forms a predetermined angle, and is formed as an inclined surface that approaches the surface of the underlayer 12 as the distance from the heating member 51a increases. .
- the substrate 20 is moved from right to left by a transfer device not shown in FIG.
- the substrate 20 is supplied between the pair of heating members 51a and 51b. Specifically, the substrate 20 is supplied such that the surface of the intermediate layer 14 faces the heating member 51a. For example, the substrate 20 is continuously supplied from a substrate roll (not shown).
- the metal lithium foil 53 is supplied between the heating members 51a and 51b from a position facing the intermediate layer 14 of the substrate 20 which is supplied between the heating members 51a and 51b.
- the metal lithium foil 53 is supplied between the heating members 51 a and 51 b from the raw metal foil roll 52 via a rotating member 54.
- the heating members 51a and 51b are melted while contacting the metallic lithium foil 53 to generate molten lithium 55, and the generated molten lithium 55 is heated by the heating members 51a and 51b.
- the molten lithium layer 56 is formed by pressing and contacting the surface of the intermediate layer 14 of the substrate 20 moving between 51b, the molten lithium layer 56 is moved in a direction in which the substrate 20 is separated from the space between the heating members 51a and 51b (see FIG. In FIG. 11, the molten lithium layer 56 is further moved in the left direction and cooled to solidify the molten lithium layer 56 until the surface layer 15 is made of metallic lithium.
- the metallic lithium foil 53 supplied to the heating members 51 a and 51 b is melted while contacting the rotating heating member 51 a, and the molten lithium 55 is deposited on the surface of the intermediate layer 14.
- the molten lithium 55 on the intermediate layer 14 moving from right to left along with the movement of the long substrate 20 is pressed against the surface of the intermediate layer 14 when passing through the film thickness adjusting member 57 provided above the heating member 51b.
- the molten lithium layer 56 made of molten lithium is deposited on the surface of the intermediate layer 14 with a predetermined thickness on the downstream side of the film thickness adjusting member 57 in contact therewith.
- the molten lithium layer 56 deposited on the surface of the intermediate layer 14 of the substrate 20 moves away from the heating member 51b with the movement of the substrate 20, the influence of heat transfer by the heating member 51b is reduced. Then, the surface layer 15 is formed by cooling until it is solidified. Thus, the negative electrode 10 for a lithium battery is obtained.
- the negative electrode 10 for a lithium battery can be manufactured. It is suitable for mass production of the negative electrode 10.
- the obtained negative electrode 10 for a lithium battery may be cut as necessary.
- the negative electrode 10 for a lithium battery is cut into a size of about 1 mm 2 or more and about 1 m 2 or less.
- the substrate 20 may be removed from the underlayer 12 as necessary.
- the timing for removing the substrate 20 from the underlayer 12 is not particularly limited, and for example, the substrate 20 can be removed after the second step.
- the thickness of the surface layer 15 (molten lithium layer 56) can be adjusted.
- the lithium battery according to the present embodiment includes an underlayer 12 made of a metal or an alloy, and a plurality of carbon nanotubes 11 as a nanocarbon material fixed to the underlayer 12 and extending from at least one surface of the underlayer 12. And an underlayer 12 covering at least one surface 12a of the underlayer 12 constituting the structure 13 and a surface of an extended portion of the plurality of carbon nanotubes 11 extending from the surface 12a. And an intermediate layer 14 made of a metal or alloy different from the above, and a negative electrode 10 for a lithium battery having a laminate 16 including a surface layer 15 made of metallic lithium, which covers the surface of the intermediate layer 14.
- FIG. 12 is a cross-sectional view schematically illustrating the lithium metal battery according to the first embodiment, which is manufactured using the negative electrode illustrated in FIG.
- the lithium battery 1 includes a positive electrode 19, a negative electrode 10 for a lithium battery, an electrolytic solution L, and a separator 18.
- the positive electrode 19 includes a positive electrode layer 19a containing a positive electrode active material, and a positive electrode current collector foil 19b coated with and holding the positive electrode active material.
- the lithium battery 1 may be a primary battery or a secondary battery.
- the charge / discharge capacity can be reduced even if charge / discharge is repeated. From the viewpoint that it can be effectively prevented, application as a secondary battery is particularly preferable.
- the positive electrode active material constituting the positive electrode layer 19a is not particularly limited, and any material can be selected from materials which can occlude and release lithium ions and have a higher potential than metallic lithium as the negative electrode active material. Can be used.
- the positive electrode active material lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium cobalt phosphate, lithium cobaltate composite oxide, lithium manganate composite oxide, lithium nickelate composite oxide, Lithium niobate composite oxide, lithium ferrate composite oxide, lithium magnesium oxide composite oxide, lithium calcium oxide composite oxide, lithium cuprate composite oxide, lithium zincate composite oxide, lithium molybdate composite oxide, tantalum Lithium oxide composite oxide, lithium tungstate composite oxide, lithium nickel cobalt aluminum composite oxide, lithium nickel cobalt manganese composite oxide, and the like.
- a positive electrode layer 19a can be obtained by adding and kneading an additive such as a conductive agent and forming a layer on the positive electrode current collector foil 19b having conductivity.
- the positive electrode current collector foil 19b is not particularly limited, and a conventionally known one can be used.
- a metal foil, a metal sheet, a conductive polymer material, or the like made of nickel, stainless steel, aluminum, titanium, or the like can be used as the positive electrode current collector foil 19b.
- the separator 18 is used for separating the negative electrode 10 and the positive electrode 19 to prevent a short circuit between the two electrodes, and a conventionally known separator can be used.
- a nonwoven fabric commonly used for a secondary battery or a permeable separator made of another porous material can be used.
- a known solid electrolyte made of a polymer gel impregnated with an electrolytic solution can be used as the separator 18.
- the electrolytic solution L contains lithium ions, and a conventionally known electrolytic solution can be used.
- This electrolytic solution can be constituted by dissolving an electrolyte in an organic solvent.
- an organic solvent conventionally known as an electrolyte for a lithium battery can be used, and is not particularly limited.
- carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones, oxolane compounds, and the like can be used, and propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate, diethyl carbonate, It is preferable to use ethyl methyl carbonate, vinylene carbonate, or the like, or a mixed solvent thereof.
- Examples of the electrolyte include, but are not particularly limited to, inorganic salts such as LiPF 6 , LiBF 4 , LiClO 4 , LiNO 3 , LiCl, LiF, and LiAsF 6, or derivatives of these inorganic salts, LiSO 3 CF 3 , and LiC (SO 3 CF).
- Organic salts such as 3 , LiN (SO 2 CF 3 ) 2 , LiN (SO 2 C 2 F 5 ) 2 , LiN (SO 2 CF 3 ) (SO 2 C 4 F 9 ) or derivatives of these organic salts And the like.
- the concentration of the electrolyte is also not particularly limited, and can be appropriately determined in consideration of the types of the electrolyte and the organic solvent.
- the negative electrode used for the lithium metal battery has been described as an example.
- the negative electrode used for the lithium air battery, the lithium ion battery, and the lithium solid battery can be similarly configured to have the negative electrode for the lithium metal battery. Since the same effect can be obtained, the configuration will be described below with reference to FIGS.
- FIG. 13 is a cross-sectional view schematically illustrating a lithium-air battery according to the second embodiment.
- the lithium air battery 1A shown in FIG. 13 includes a positive electrode 19A, a negative electrode 10, an electrolytic solution L, and a separator 18, and has a battery configuration similar to that of FIG. It has a different configuration. That is, the positive electrode 19A includes the positive electrode catalyst layer 19c and the positive electrode current collecting network 19d from the separator 18 side.
- FIG. 14 is a cross-sectional view schematically showing a lithium ion battery according to the third embodiment.
- the lithium ion battery 1B shown in FIG. 14 includes a positive electrode 19, a negative electrode 10B, an electrolytic solution L, and a separator 18.
- the lithium ion battery 1B has the same configuration as the positive electrode 19 and the separator 18 of the lithium metal battery 1 shown in FIG.
- the surface layer 15 of the negative electrode 10B is made of metal lithium
- the surface layer of the negative electrode 10B in the lithium ion battery 1B is a negative electrode mixture layer obtained by solidifying graphite or silicon with a binder instead of the metal lithium.
- the negative electrode mixture layer 60 is formed by impregnating the negative electrode mixture layer 60 with the electrolytic solution L.
- FIG. 15 is a sectional view schematically showing a lithium solid state battery according to the fourth embodiment.
- the lithium solid battery 1C shown in FIG. 15 includes the positive electrode 19, the negative electrode 10C, and the solid electrolyte layer 61, and has no separator or electrolyte.
- the configurations of the negative electrode 10C and the positive electrode 19 of the lithium solid battery 1C are the same as those of the negative electrode 10 of the lithium metal battery 1 shown in FIG. 12 and the positive electrode 19 of the lithium ion battery 1B shown in FIG.
- Example 1 In Example 1, first, a negative electrode for a lithium metal battery was manufactured.
- the surface of a substrate made of rolled copper foil is subjected to electrolytic plating (composite plating), and a plurality of carbon nanotubes and a part of the carbon nanotubes are embedded and fixed.
- a structure including the extended base layer was manufactured (structure forming step).
- a copper sulfate plating solution in which carbon nanotubes are dispersed is used as the electrolytic plating solution 24, and the temperature of the electrolytic plating solution 24 is maintained at 25 ° C., and the anode electrode 23 a is 0.1 A / cm 2 or more.
- An electrolytic plating treatment was performed while applying a current of 8 A / cm 2 or less and stirring the electrolytic plating solution 24 with a chemical pump.
- a substrate having a structure in which a base layer made of metal copper plating was formed on only one surface of the surface of the rolled copper foil and a plurality of carbon nanotubes were fixed to the base layer was produced.
- an intermediate layer made of metal tin is formed by an electrolytic plating method using the above-described plating apparatus 31 (see FIG. 5) (intermediate layer forming step). Subsequently, the above-described surface is formed on the surface of the intermediate layer.
- a surface layer made of metallic lithium was formed by a lithium metal deposition method using lithium contained in the positive electrode active material (surface layer forming step), and a negative electrode for a lithium battery of Example 1 was produced. On the surface of the negative electrode for a lithium battery of Example 1, the surface density of carbon nanotubes, the deposition amount per unit area of the intermediate layer, and the deposition amount per unit area of metallic lithium on the surface layer were measured.
- the coin-type lithium secondary battery of Example 1 is configured by stacking a negative electrode, a separator, a positive electrode layer including a lithium-cobalt composite oxide LCO (LiCoO 2 ), and a positive electrode including a positive electrode current collector foil. ing. Note that LiPF 6 was used as an electrolyte of the electrolytic solution.
- Comparative Example 1 In Comparative Example 1, first, a negative electrode for a lithium battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the intermediate layer forming step of Example 1 was omitted and the intermediate layer was not formed. As a result of measuring the areal density of the carbon nanotubes and the deposition amount per unit area of metallic lithium on the surface layer on the surface of the negative electrode for a lithium battery of Comparative Example 1, the areal density of the carbon nanotubes was 0.1 mg / cm 2. And the deposition amount of metallic lithium per unit area was 0.6 mg / cm 2 . Thereafter, using this negative electrode for a lithium battery, a coin-type lithium secondary battery of Comparative Example 1 was produced.
- the coin-type lithium secondary battery of Comparative Example 1 has a negative electrode for a lithium battery having a configuration in which no intermediate layer is formed, a separator, and a positive electrode layer containing lithium-cobalt composite oxide LCO (LiCoO 2 ) and It is configured by laminating a positive electrode made of a positive electrode current collector foil.
- LiPF 6 similar to that of Example 1 was used as an electrolyte of the electrolytic solution.
- Example 1 ⁇ Evaluation method> For each of the manufactured lithium secondary batteries of Example 1 and Comparative Example 1, a cycle test in which charging and discharging were repeated was performed. For each of these batteries, after forming the battery at a temperature of 25 ° C., an operation of charging to 4.2 V at a rate of 0.65 C and an operation of discharging to 3.0 V at the same rate were alternately repeated.
- FIG. 16 shows the result of plotting the relationship between the number of cycles and the capacity retention rate (%), assuming that the discharge capacity at the first cycle (initial discharge capacity) is 100%.
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Abstract
Description
[1]金属または合金からなる下地層、および、該下地層に固定され、前記下地層の少なくとも一方の表面から延在する複数のナノカーボン材料を有する構造体と、該構造体を構成する前記下地層の前記少なくとも一方の表面、および該表面から延在する前記複数のナノカーボン材料の延在部分の表面を被覆する、前記下地層とは異なる金属または合金からなる中間層と、該中間層の表面に、金属リチウム、黒鉛またはケイ素によって形成してなる表面層とを含んで構成された積層体を有するリチウム電池用負極。
[2]前記表面層を形成する材料が、金属リチウムである、上記[1]に記載のリチウム電池用負極。
[3]前記表面層を形成する金属リチウムの堆積量が、0.01mg/cm2以上、5mg/cm2以下の範囲である、上記[2]に記載のリチウム電池用負極。
[4]前記中間層が、リチウムとの合金形成が可能な金属または合金からなる、上記[2]または[3]に記載のリチウム電池用負極。
[5]前記表面層を形成する材料が、黒鉛またはケイ素である、上記[1]に記載のリチウム電池用負極。
[6]前記中間層が、Al、Zn、Cr、Fe、Ni、Sn、Pb、Cu、Ag、Pt、Au、In、PdおよびMgから選択される、1種の金属または1種以上を含む合金からなる、上記[2]~[5]のいずれか1項に記載のリチウム電池用負極。
[7]前記中間層が、Sn、Al、Au、Mg、AgもしくはZnの金属、またはCuとSnもしくはNiとの合金からなる、上記[6]に記載のリチウム電池用負極。
[8]前記中間層の厚みが、0.01μm以上、3μm以下の範囲である、上記[1]~[7]のいずれか1項に記載のリチウム電池用負極。
[9]前記ナノカーボン材料は、カーボンナノチューブを含む、上記[1]~[8]のいずれか1項に記載のリチウム電池用負極。
[10]前記ナノカーボン材料は、カーボンナノファイバーをさらに含む、上記[9]に記載のリチウム電池用負極。
[11]リチウム二次電池用負極である、上記[1]~[10]のいずれか1項に記載のリチウム電池用負極。
[12]ナノカーボン材料を混合した電解めっき液を用い、電解めっき法によって、基板の表面に、金属または合金からなる下地層と、該下地層に固定され、前記下地層の少なくとも一方の表面から延在する複数のナノカーボン材料とを有する構造体を形成する工程と、前記構造体を構成する前記下地層の前記少なくとも一方の表面、および該表面から延在する前記複数のナノカーボン材料の延在部分の表面に、前記下地層とは異なる金属または合金からなる中間層を堆積させて形成する工程と、前記中間層の表面に、金属リチウム、黒鉛またはケイ素によって表面層を形成して積層体を構成する工程とを含むリチウム電池用負極の製造方法。
[13]前記中間層を堆積させて形成する工程は、電解めっき法または無電解めっき法によって行う上記[12]に記載のリチウム電池用負極の製造方法。
[14]前記中間層を堆積させて形成する工程は、蒸着法によって行う上記[12]に記載のリチウム電池用負極の製造方法。
[15]前記表面層を形成する材料が金属リチウムである、上記[12]~[14]のいずれか1項に記載のリチウム電池用負極の製造方法。
[16]前記表面層を形成する工程は、対極として金属リチウムまたはリチウム化合物を用いた電解めっき法によって行う、上記[15]に記載のリチウム電池用負極の製造方法。
[17]前記表面層を形成する工程は、金属リチウムを蒸着することによって行う、上記[15]に記載のリチウム電池用負極の製造方法。
[18]上記[1]~[11]のいずれか1項に記載のリチウム電池用負極を含むリチウム電池。 The gist configuration of the present invention is as follows.
[1] A structure having an underlayer made of a metal or an alloy, a plurality of nanocarbon materials fixed to the underlayer, and extending from at least one surface of the underlayer, and the structure constituting the structure An intermediate layer made of a metal or an alloy different from the underlayer, covering the at least one surface of the underlayer, and the surface of the extended portion of the plurality of nanocarbon materials extending from the surface; and the intermediate layer A negative electrode for a lithium battery having a laminate comprising a surface layer formed of lithium metal, graphite or silicon.
[2] The negative electrode for a lithium battery according to the above [1], wherein the material forming the surface layer is metallic lithium.
[3] The negative electrode for a lithium battery according to the above [2], wherein a deposition amount of the metal lithium forming the surface layer is in a range of 0.01 mg / cm 2 or more and 5 mg / cm 2 or less.
[4] The negative electrode for a lithium battery according to the above [2] or [3], wherein the intermediate layer is made of a metal or an alloy capable of forming an alloy with lithium.
[5] The negative electrode for a lithium battery according to [1], wherein the material forming the surface layer is graphite or silicon.
[6] The intermediate layer includes one or more metals selected from Al, Zn, Cr, Fe, Ni, Sn, Pb, Cu, Ag, Pt, Au, In, Pd, and Mg. The negative electrode for a lithium battery according to any one of the above [2] to [5], comprising an alloy.
[7] The negative electrode for a lithium battery according to the above [6], wherein the intermediate layer is made of a metal of Sn, Al, Au, Mg, Ag or Zn, or an alloy of Cu and Sn or Ni.
[8] The negative electrode for a lithium battery according to any one of [1] to [7], wherein the thickness of the intermediate layer is in the range of 0.01 μm or more and 3 μm or less.
[9] The negative electrode for a lithium battery according to any one of [1] to [8], wherein the nanocarbon material includes a carbon nanotube.
[10] The negative electrode for a lithium battery according to [9], wherein the nanocarbon material further includes carbon nanofibers.
[11] The negative electrode for a lithium battery according to any one of the above [1] to [10], which is a negative electrode for a lithium secondary battery.
[12] Using an electrolytic plating solution mixed with a nanocarbon material, a base layer made of a metal or an alloy is fixed on the surface of the substrate by an electrolytic plating method, and at least one surface of the base layer is fixed to the base layer. Forming a structure having a plurality of nanocarbon materials extending therefrom; and forming at least one surface of the underlayer constituting the structure, and extending the plurality of nanocarbon materials extending from the surface. Depositing and forming an intermediate layer made of a metal or an alloy different from the underlayer on the surface of the existing portion; and forming a surface layer on the surface of the intermediate layer with metallic lithium, graphite or silicon to form a laminate. And a method for producing a negative electrode for a lithium battery.
[13] The method for producing a negative electrode for a lithium battery according to the above [12], wherein the step of depositing and forming the intermediate layer is performed by an electrolytic plating method or an electroless plating method.
[14] The method for producing a negative electrode for a lithium battery according to [12], wherein the step of depositing and forming the intermediate layer is performed by a vapor deposition method.
[15] The method for producing a negative electrode for a lithium battery according to any one of the above [12] to [14], wherein the material forming the surface layer is metallic lithium.
[16] The method for producing a negative electrode for a lithium battery according to the above [15], wherein the step of forming the surface layer is performed by an electrolytic plating method using lithium metal or a lithium compound as a counter electrode.
[17] The method for producing a negative electrode for a lithium battery according to the above [15], wherein the step of forming the surface layer is performed by depositing metallic lithium.
[18] A lithium battery including the negative electrode for a lithium battery according to any one of [1] to [11].
図1は、本実施形態に係るリチウム電池に含まれるリチウム金属電池に用いられる負極10(以下、単に「負極10」ともいう)の断面の構成を模式的に示す図である。図1に示す負極10は、基板20と、基板20の表面に形成される金属または合金からなる下地層12、および、該下地層12に固定され下地層12の少なくとも一方の表面から延在する複数のナノカーボン材料としてのカーボンナノチューブ(CNT)11を有する構造体13と、構造体13上に形成される中間層14と、中間層14上に形成される金属リチウムからなる表面層15とを含んで構成された積層体16を有する。積層体16は、表面が平滑な面ではなく3次元的な表面構造を形成している。また、負極10が用いられるリチウム金属電池は、負極活物質がリチウムである。 <Negative electrode for lithium battery and its structure>
FIG. 1 is a diagram schematically illustrating a cross-sectional configuration of a negative electrode 10 (hereinafter, also simply referred to as “
図1に示す構造体13は、ナノカーボン材料としてのカーボンナノチューブ11と、このカーボンナノチューブ11の少なくとも一部を埋め込んで固定する下地層12とを有しており、負極集電体として機能するものである。 [Structure]
The
ここでは、ナノカーボン材料の一例としてカーボンナノチューブを用いているが、本発明は、ナノカーボン材料がカーボンナノチューブに限定されるものではなく、例えば、カーボンナノファイバーやセルロースナノファイバーなどで構成されるナノカーボン材料を備えるリチウム電池用負極も本発明に含まれる。なお、図1では、説明の便宜上、積層体16、特にカーボンナノチューブ11は、実際の寸法よりも大きく示していて、実際の寸法とは異なる。 As shown in FIG. 1, the
Here, a carbon nanotube is used as an example of a nanocarbon material. However, the present invention is not limited to a carbon nanotube, and the nanocarbon material is not limited to a carbon nanofiber or a cellulose nanofiber. A negative electrode for a lithium battery including a carbon material is also included in the present invention. In FIG. 1, for convenience of explanation, the
中間層14は、金属または合金からなる下地層12と負極活物質(金属リチウム)からなる表面層15との間、およびカーボンナノチューブ11と表面層15との間に配置され、下地層12とは異なる金属または合金で構成される。本実施形態では、このように中間層14を配置することによって、従来のリチウム電池の場合のように、リチウム電池の充放電を繰り返すことによって充放電容量が低下するのを有効に防止することができる。 [Intermediate layer]
The
本実施形態のリチウム電池用負極10では、表面層15として、金属リチウムからなる負極活物質が用いられ、表面層15は金属リチウムが堆積された層で構成される。 [Surface layer]
In the
基板20は、導電率の高い金属または合金から構成されることが好ましい。例えば、基板20は、銅、銅合金、ニッケル、ニッケル合金、亜鉛、亜鉛合金、アルミニウム、アルミニウム合金、金、金合金、銀、銀合金、およびステンレス鋼の群から選択される金属または合金から構成することができ、形状としては、箔、フィルム、板などが挙げられる。また、基板20は、要求される特性に応じて、導電性ポリマーのような種々の添加材を含んでもよい。 [substrate]
The
次に、本実施形態に係るリチウム電池用負極10の製造方法について説明する。 (Method of manufacturing negative electrode for lithium battery)
Next, a method for manufacturing the
まず、構造体形成工程について説明する。 (Structure forming step)
First, the structure forming step will be described.
次に、中間層形成工程について説明する。 (Intermediate layer forming step)
Next, the intermediate layer forming step will be described.
次に、表面層形成工程について説明する。 (Surface layer forming step)
Next, the surface layer forming step will be described.
本実施形態に係るリチウム電池は、金属または合金からなる下地層12、および、該下地層12に固定され、下地層12の少なくとも一方の表面から延在する複数のナノカーボン材料としてのカーボンナノチューブ11を有する構造体13と、該構造体13を構成する下地層12の少なくとも一方の表面12a、および該表面12aから延在する複数のカーボンナノチューブ11の延在部分の表面を被覆する、下地層12とは異なる金属または合金からなる中間層14と、該中間層14の表面を被覆する、金属リチウムからなる表面層15とを含んで構成された積層体16を有するリチウム電池用負極10を含む。 <Lithium metal battery>
The lithium battery according to the present embodiment includes an
図13は、第二の実施形態に係るリチウム空気電池を模式的に示す断面図である。図13に示すリチウム空気電池1Aは、正極19Aと、負極10と、電解液Lと、セパレータ18とを含んで構成されており、図12と同様の電池構成をしているが、正極19Aが異なる構成となっている。すなわち、正極19Aは、セパレータ18側から、正極触媒層19cと、正極集電網19dとで構成されている。 <Lithium air battery>
FIG. 13 is a cross-sectional view schematically illustrating a lithium-air battery according to the second embodiment. The
図14は、第三の実施形態に係るリチウムイオン電池を模式的に示す断面図である。図14に示すリチウムイオン電池1Bは、正極19と、負極10Bと、電解液Lと、セパレータ18とを含んで構成されている。このリチウムイオン電池1Bは、正極19およびセパレータ18については図12に示すリチウム金属電池1の正極19およびセパレータ18と同様の構成であるが、負極10の表面層については、リチウム金属電池1の負極10の表面層15が金属リチウムで構成されているのに対し、リチウムイオン電池1Bでは負極10Bの表面層は、この金属リチウムの代わりに、黒鉛またはケイ素を結着材で固めた負極合材層60で形成され、この負極合材層60に電解液Lを含浸させたもので構成されている点で異なっている。 <Lithium ion battery>
FIG. 14 is a cross-sectional view schematically showing a lithium ion battery according to the third embodiment. The
図15は、第四の実施形態に係るリチウム固体電池を模式的に示す断面図である。図15に示すリチウム固体電池1Cは、正極19と、負極10Cと、固体電解質層61とを含んで構成されており、セパレータや電解液は存在しない。このリチウム固体電池1Cの負極10Cおよび正極19の構成はそれぞれ、図12に示すリチウム金属電池1の負極10および図14に示すリチウムイオン電池1Bとの正極19の各構成と同様である。 <Lithium solid battery>
FIG. 15 is a sectional view schematically showing a lithium solid state battery according to the fourth embodiment. The lithium
実施例1では、まず、リチウム金属電池用負極を作製した。 (Example 1)
In Example 1, first, a negative electrode for a lithium metal battery was manufactured.
その後、このリチウム電池用負極を用いて、実施例1のコイン型のリチウム二次電池を作製した。 Next, an intermediate layer made of metal tin is formed by an electrolytic plating method using the above-described plating apparatus 31 (see FIG. 5) (intermediate layer forming step). Subsequently, the above-described surface is formed on the surface of the intermediate layer. A surface layer made of metallic lithium was formed by a lithium metal deposition method using lithium contained in the positive electrode active material (surface layer forming step), and a negative electrode for a lithium battery of Example 1 was produced. On the surface of the negative electrode for a lithium battery of Example 1, the surface density of carbon nanotubes, the deposition amount per unit area of the intermediate layer, and the deposition amount per unit area of metallic lithium on the surface layer were measured. Is 0.1 mg / cm 2 , the deposition amount per unit area of the intermediate layer is 0.1 mg / cm 2 , and the deposition amount per unit area of metallic lithium is 0.6 mg / cm 2. Was.
Thereafter, using this negative electrode for a lithium battery, a coin-type lithium secondary battery of Example 1 was produced.
比較例1では、まず、実施例1の中間層形成工程を省略して、中間層を形成しなかったこと以外は実施例1と同様にして比較例1のリチウム電池用負極を作製した。この比較例1のリチウム電池用負極の表面における、カーボンナノチューブの面密度、および表面層の金属リチウムの単位面積当たりの堆積量をそれぞれ測定した結果、カーボンナノチューブの面密度は0.1mg/cm2であり、金属リチウムの単位面積当たりの堆積量は0.6mg/cm2であった。
その後、このリチウム電池用負極を用いて、比較例1のコイン型のリチウム二次電池を作製した。 (Comparative Example 1)
In Comparative Example 1, first, a negative electrode for a lithium battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the intermediate layer forming step of Example 1 was omitted and the intermediate layer was not formed. As a result of measuring the areal density of the carbon nanotubes and the deposition amount per unit area of metallic lithium on the surface layer on the surface of the negative electrode for a lithium battery of Comparative Example 1, the areal density of the carbon nanotubes was 0.1 mg / cm 2. And the deposition amount of metallic lithium per unit area was 0.6 mg / cm 2 .
Thereafter, using this negative electrode for a lithium battery, a coin-type lithium secondary battery of Comparative Example 1 was produced.
作製した実施例1および比較例1の各リチウム二次電池について、充放電を繰り返すサイクル試験を行った。
これらの各電池に対して、温度25℃にて電池を化成後、0.65Cのレートで4.2Vまで充電する操作と、同じレートで3.0Vまで放電させる操作を交互に繰り返した。1サイクル目の放電容量(初期放電容量)を100%として、サイクル数と容量維持率(%)との関係をプロットした結果を図16に示す。 <Evaluation method>
For each of the manufactured lithium secondary batteries of Example 1 and Comparative Example 1, a cycle test in which charging and discharging were repeated was performed.
For each of these batteries, after forming the battery at a temperature of 25 ° C., an operation of charging to 4.2 V at a rate of 0.65 C and an operation of discharging to 3.0 V at the same rate were alternately repeated. FIG. 16 shows the result of plotting the relationship between the number of cycles and the capacity retention rate (%), assuming that the discharge capacity at the first cycle (initial discharge capacity) is 100%.
1A リチウム空気電池
1B リチウムイオン電池
1C リチウム固体電池
10 リチウム金属電池用負極
11 ナノカーボン材料(カーボンナノチューブ)
12 下地層
13 構造体
14 中間層
15 表面層
16 積層体
18 セパレータ
19a 正極電極層
19b 正極集電箔
20 基板
30 複合めっき装置
31 めっき装置
42 金属リチウム箔
43 溶融リチウム
44、55、56 溶融リチウム層
50 積層体連続形成装置
L 電解液
DESCRIPTION OF
DESCRIPTION OF
Claims (18)
- 金属または合金からなる下地層、および、該下地層に固定され、前記下地層の少なくとも一方の表面から延在する複数のナノカーボン材料を有する構造体と、
該構造体を構成する前記下地層の前記少なくとも一方の表面、および該表面から延在する前記複数のナノカーボン材料の延在部分の表面を被覆する、前記下地層とは異なる金属または合金からなる中間層と、
該中間層の表面に、金属リチウム、黒鉛またはケイ素によって形成してなる表面層と
を含んで構成された積層体を有するリチウム電池用負極。 A base layer made of a metal or an alloy, and a structure fixed to the base layer and having a plurality of nanocarbon materials extending from at least one surface of the base layer;
The at least one surface of the underlayer constituting the structure, and the surface of the extending portion of the plurality of nanocarbon materials extending from the surface are made of a metal or alloy different from the underlayer. An intermediate layer,
A negative electrode for a lithium battery having a laminate comprising a surface layer formed of metallic lithium, graphite or silicon on the surface of the intermediate layer. - 前記表面層を形成する材料が、金属リチウムである、請求項1に記載のリチウム電池用負極。 The negative electrode for a lithium battery according to claim 1, wherein the material forming the surface layer is metallic lithium.
- 前記表面層を形成する前記金属リチウムの堆積量が、0.01mg/cm2以上、5mg/cm2以下の範囲である、請求項2に記載のリチウム電池用負極。 3. The negative electrode for a lithium battery according to claim 2, wherein a deposition amount of the metal lithium forming the surface layer is in a range of 0.01 mg / cm 2 or more and 5 mg / cm 2 or less. 4.
- 前記中間層が、リチウムとの合金形成が可能な金属または合金からなる、請求項2または3に記載のリチウム電池用負極。 4. The negative electrode for a lithium battery according to claim 2, wherein the intermediate layer is made of a metal or an alloy capable of forming an alloy with lithium.
- 前記表面層を形成する材料が、黒鉛またはケイ素である、請求項1に記載のリチウム電池用負極。 The negative electrode for a lithium battery according to claim 1, wherein the material forming the surface layer is graphite or silicon.
- 前記中間層が、Al、Zn、Cr、Fe、Ni、Sn、Pb、Cu、Ag、Pt、Au、In、PdおよびMgから選択される、1種の金属または1種以上を含む合金からなる、請求項2~5のいずれか1項に記載のリチウム電池用負極。 The intermediate layer is made of one metal selected from Al, Zn, Cr, Fe, Ni, Sn, Pb, Cu, Ag, Pt, Au, In, Pd, and Mg, or an alloy containing one or more metals. The negative electrode for a lithium battery according to any one of claims 2 to 5.
- 前記中間層が、Sn、Al、Au、Mg、AgもしくはZnの金属、またはCuとSnもしくはNiとの合金からなる、請求項6に記載のリチウム電池用負極。 The negative electrode for a lithium battery according to claim 6, wherein the intermediate layer is made of a metal of Sn, Al, Au, Mg, Ag, or Zn, or an alloy of Cu and Sn or Ni.
- 前記中間層の厚みが、0.01μm以上、3μm以下の範囲である、請求項1~7のいずれか1項に記載のリチウム電池用負極。 (8) The negative electrode for a lithium battery according to any one of (1) to (7), wherein the thickness of the intermediate layer is in the range of 0.01 μm or more and 3 μm or less.
- 前記ナノカーボン材料は、カーボンナノチューブを含む、請求項1~8のいずれか1項に記載のリチウム電池用負極。 The negative electrode for a lithium battery according to any one of claims 1 to 8, wherein the nanocarbon material includes a carbon nanotube.
- 前記ナノカーボン材料は、カーボンナノファイバーをさらに含む、請求項9に記載のリチウム電池用負極。 The negative electrode for a lithium battery according to claim 9, wherein the nanocarbon material further includes a carbon nanofiber.
- リチウム二次電池用負極である、請求項1~10のいずれか1項に記載のリチウム電池用負極。 The negative electrode for a lithium battery according to any one of claims 1 to 10, which is a negative electrode for a lithium secondary battery.
- ナノカーボン材料を混合した電解めっき液を用い、電解めっき法によって、基板の表面に、金属または合金からなる下地層と、該下地層に固定され、前記下地層の少なくとも一方の表面から延在する複数のナノカーボン材料とを有する構造体を形成する工程と、
前記構造体を構成する前記下地層の前記少なくとも一方の表面、および該表面から延在する前記複数のナノカーボン材料の延在部分の表面に、前記下地層とは異なる金属または合金からなる中間層を堆積させて形成する工程と、
前記中間層の表面に、金属リチウム、黒鉛またはケイ素によって表面層を形成して積層体を構成する工程と
を含むリチウム電池用負極の製造方法。 Using an electroplating solution in which a nanocarbon material is mixed, a base layer made of a metal or an alloy, and fixed to the base layer, extending from at least one surface of the base layer, by an electroplating method, on the surface of the substrate. Forming a structure having a plurality of nanocarbon materials,
An intermediate layer made of a metal or alloy different from the underlayer on the at least one surface of the underlayer constituting the structure, and on the surface of the extending portion of the plurality of nanocarbon materials extending from the surface; Depositing and forming
Forming a surface layer of metallic lithium, graphite or silicon on the surface of the intermediate layer to form a laminate. - 前記中間層を堆積させて形成する工程は、電解めっき法または無電解めっき法によって行う、請求項12に記載のリチウム電池用負極の製造方法。 The method for manufacturing a negative electrode for a lithium battery according to claim 12, wherein the step of depositing and forming the intermediate layer is performed by an electrolytic plating method or an electroless plating method.
- 前記中間層を堆積させて形成する工程は、蒸着法によって行う、請求項12に記載のリチウム電池用負極の製造方法。 The method for producing a negative electrode for a lithium battery according to claim 12, wherein the step of depositing and forming the intermediate layer is performed by a vapor deposition method.
- 前記表面層を形成する材料が金属リチウムである、請求項12~14のいずれか1項に記載のリチウム電池用負極の製造方法。 The method for producing a negative electrode for a lithium battery according to any one of claims 12 to 14, wherein the material forming the surface layer is lithium metal.
- 前記表面層を形成する工程は、対極として金属リチウムまたはリチウム化合物を用いた電解めっき法によって行う、請求項15に記載のリチウム電池用負極の製造方法。 The method for producing a negative electrode for a lithium battery according to claim 15, wherein the step of forming the surface layer is performed by an electrolytic plating method using lithium metal or a lithium compound as a counter electrode.
- 前記表面層を形成する工程は、金属リチウムを蒸着することによって行う、請求項15に記載のリチウム電池用負極の製造方法。 The method for producing a negative electrode for a lithium battery according to claim 15, wherein the step of forming the surface layer is performed by depositing metallic lithium.
- 請求項1~11のいずれか1項に記載のリチウム電池用負極を含むリチウム電池。 A lithium battery comprising the negative electrode for a lithium battery according to any one of claims 1 to 11.
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