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    • 专利摘要:
    The present invention relates to a protected lithium electrode structure for a lithium-air cell comprising: negative electrode current collector (3); negative electrode active material layer (5) made of lithium metal, alloy containing mainly lithium, or compound containing mainly lithium and stacked on the negative electrode current collector (3); and separator (7) stacked on the negative electrode active material layer (5), and wherein the negative electrode active material layer (5) is sealed by the separator (7) and the current collector (5). negative electrode (3), and means capturing the fine lithium powder produced during charging and discharging is provided between the negative electrode active material layer (5) and the separator (7).
    公开号:FR3063576A1
    申请号:FR1851674
    申请日:2018-02-27
    公开日:2018-09-07
    发明作者:Hiroaki Izumi；Masaya Nomura；Hironari Minami
    申请人:Suzuki Motor Co Ltd；
    IPC主号:
    专利说明:

    ® FRENCH REPUBLIC
    NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number: 3,063,576 (to be used only for reproduction orders) (© National registration number: 18 51674
    COURBEVOIE © Int Cl 8 : H 01 M4 / 90 (2017.01), H 01 M 12/06
    A1 PATENT APPLICATION
    ©) Date of filing: 27.02.18. © Applicant (s): SUZUKI MOTOR CORPORATION - © Priority: 01.03.17 JP 2017038307. JP. @ Inventor (s): IZUMI HIROAKI, NOMURA MASAYA and MINAMI HIRONARI. (43) Date of public availability of the request: 07.09.18 Bulletin 18/36. ©) List of documents cited in the report preliminary research: The latter was not established on the date of publication of the request. (© References to other national documents ® Holder (s): SUZUKI MOTOR CORPORATION. related: ©) Extension request (s): © Agent (s): CABINET PLASSERAUD.
    (64) PROTECTED LITHIUM ELECTRODE STRUCTURE FOR LITHIUM-AIR CELL.
    FR 3,063,576 - A1 (6 /) The present invention relates to a protected lithium electrode structure for a lithium-air battery comprising: negative electrode current collector (3); layer of negative electrode active material (5) consisting of lithium metal, an alloy containing mainly lithium, or compound containing mainly lithium and stacked on the negative electrode current collector (3); and separator (7) stacked on the layer of active material of negative electrode (5), and in which the layer of active material of negative electrode (5) is sealed by the separator (7) and the current collector negative electrode (3), and means for capturing the fine lithium powder produced during charging and discharging is provided between the layer of active material of negative electrode (5) and the separator (7).

    PROTECTED LITHIUM ELECTRODE STRUCTURE FOR BATTERY
    LITHIUM-AIR
    The present invention relates to a protected lithium electrode structure used for a lithium-air battery.
    Metal-air cells have recently been proposed as a next generation of cells capable of having a higher energy density than conventional lithium ion cells. A metal-air cell is a cell with an active material with a negative electrode which is a metal and an active material with a positive electrode which is atmospheric oxygen. In addition, this metal-air cell using lithium metal as the active material for a negative electrode is the subject of particular attention since the cell would theoretically generate more energy per unit of weight. Such a metal-air cell which uses lithium metal as the active material for a metal negative electrode is called a "lithium-air cell. "
    Lithium-air batteries are generally classified into two types: one in which an aqueous electrolyte is used indoors, and another in which a non-aqueous electrolyte is used indoors. A lithium-air battery that uses an aqueous electrolyte has an advantage in that it is less affected by humidity in the air than a lithium-air battery that uses a non-aqueous electrolyte. Note that it is necessary to isolate a lithium metal used for the negative electrode active material from the atmosphere and from the aqueous solution, since lithium metal reacts chemically with oxygen and water when it comes into contact with them. For the purpose of this isolation, a method has been proposed providing for example a solid electrolyte conductive of lithium ions as an insulating layer.
    For example, as a lithium-air battery which uses an aqueous electrolyte, Patent Document 1 describes a lithium-air battery comprising a protected lithium electrode in which a buffer layer of polymer electrolyte is formed on a surface of a lithium metal in the form of a plate, and is covered with a glass ceramic conducting lithium ions.
    Patent document
    Patent document 1 JP 2010-192313 A
    When the lithium-air battery described in Patent Document 1 is put into practice, the lithium metal used as active material of negative electrode is defined as a metal (current collector of negative electrode) serving as a terminal. negative electrode. There may be a case in which, when the lithiumair cell having such a structure is charged and discharged several times, lithium metal dendrites are deposited on a portion (the rear surface, for example) of the negative electrode terminal for load. In addition, there may be a case in which, when one end of a dendrite breaks, a fine powder of lithium (dead lithium) is produced and is dispersed in the electrolyte solution. This dispersed lithium powder does not contribute to charging or discharging, as it moves away from the negative electrode terminal. As a result, the charging and discharging performance of the lithium-air battery gradually decreases as the dead lithium increases.
    In light of the above circumstances, an object of the present invention is to provide a protected lithium electrode structure used for a lithium-air cell, the charge and discharge performance of which present less risk of degradation.
    To achieve the above object, a protected lithium electrode structure for a lithium-air battery, according to an aspect of the present invention, comprises: a negative electrode current collector; a layer of negative electrode active material which consists of a lithium metal, an alloy containing mainly lithium, or a compound containing mainly lithium and which is stacked on the negative electrode current collector; and a separator stacked on the negative electrode active material layer, wherein the negative electrode active material layer is sealed by the negative electrode current separator and collector, and a fine powder capture layer lithium which captures the fine lithium metal powder produced during the charge and discharge provided between the layer of active material of negative electrode and the separator. It should be noted that the separator can be, for example, a sheet of porous resin or the equivalent.
    The present invention includes: a negative electrode current collector; a layer of negative electrode active material which is a lithium metal, an alloy containing mainly lithium, or a compound containing mainly lithium and which is stacked on the negative electrode current collector; and a separator stacked on the negative electrode active material layer, wherein the negative electrode active material layer is sealed by the negative electrode current separator and collector, and a fine powder capture layer lithium which captures the fine lithium metal powder produced during the charge and discharge provided between the layer of active material of negative electrode and the separator. This is why it is possible to confine the fine lithium metal powder produced during charging and discharging in the capture layer of the fine lithium powder. This makes it possible to obtain more lithium metal which contributes to charging and discharging and to improve the utilization rate of lithium metal, since it is possible to prevent the fine powder of lithium metal from dispersing in the solution d 'electrolyte. The charging and discharging performance is therefore not easily degraded and it is possible to charge and discharge several times. As a result, the charge and discharge property can be improved.
    Ligure 1 is a sectional view illustrating a lithium electrode protected from a lithium-air battery according to a first embodiment.
    Ligure 2 is an enlarged view of a section illustrating an enlarged protected lithium electrode of the lithium-air battery according to the first embodiment.
    Ligure 3 is an enlarged view of a section illustrating a negative electrode of the lithium-air battery according to the first embodiment.
    Ligure 4 is a plan view illustrating an example of the negative electrode of the lithium-air battery according to the first embodiment.
    Ligure 5 illustrates another example of the negative electrode of the lithium-air cell according to the first embodiment: Ligure 5A is a plan view of the negative electrode; and Ligure 5B is a plan view illustrating a state in which a bag-shaped separator is deployed to store the negative electrode.
    Ligure 6 is a sectional view illustrating a lithium electrode protected from a lithium-air battery according to a second embodiment.
    Ligure 7 is a plan view illustrating a negative electrode of a lithium-air cell according to Example 1.
    Ligure 8 is a bottom view illustrating the negative electrode of the lithium-air battery according to Example 1.
    Ligure 9 is a plan view illustrating a negative electrode used to establish a performance comparison with the negative electrode shown in Ligure 7 and Ligure 8.
    Ligure 10 is a bottom view illustrating the negative electrode used to establish a performance comparison with the negative electrode shown in Ligure 7 and Ligure 8.
    Ligure 11 is a graph illustrating a relationship between time and a charge and discharge voltage of the lithium-air cell according to Example 1.
    Hereinafter, with reference to the accompanying drawings, a description is provided for the embodiments of a protected lithium electrode structure for a lithium-air battery according to the present invention in a detailed and precise manner.
    First embodiment
    First, a description is provided for a protected lithium electrode structure for a lithium-air cell according to a first embodiment using Ligure 1. As illustrated in Ligure 1, a protected lithium electrode 1 of the lithium-air cell according to the first embodiment has a stacked structure in which laminated films of upper and lower metal sheets 2, 2 sandwich a negative electrode 30 and a solid electrolyte 8 to isolate the negative electrode, for example, rheumatism. The laminated metal sheet film 2 on the upper side in the figure is a sheet in which three layers are stacked in order of a resin layer 21 such as a heat sealable PP resin sheet, a sheet of metal 22, and a resin layer 23 such as a sheet of heat-resistant PET resin from the inside (bottom side in the figure) to the outside (top side in the figure). Likewise, the laminated film of metal sheets 2 on the lower side in the figure is a sheet in which three layers are stacked in order of the resin layer 21, the metal sheet layer 22, and the resin layer 23 from the inside (upper side in the figure) to the outside (lower side in the figure).
    The laminated film of metal sheets 2 on the upper side in Ligure 1 has an opening portion 4 provided in the center or substantially in the center. This opening portion 4 is a quadrilateral when viewed from the upper side in the figure. In addition, the solid electrolyte 8 for isolating the negative electrode consisting, for example, of a glass ceramic, for example from humidity, is supplied on the lower side of the opening portion 4 of the laminated film of sheets of metal 2. The solid electrolyte 8 mentioned here refers to a solid substance which, when a voltage is applied to it, allows the permeation of ions (lithium ions). In the embodiment, this solid electrolyte 8 has a relatively thin plate shape. In addition, the size of the upper surface of this solid electrolyte 8 is slightly larger than the opening portion 4 of the laminated film of metal sheets 2.
    A peripheral edge portion of the opening portion 4 of the laminated film of upper metal sheets 2 is welded directly to the upper surface of the solid electrolyte 8, or preferably with a heat-sealing material 10 in between (see Figure 2 ). The solid electrolyte 8 thus closes this opening portion 4. The closed opening portion 4 improves safety by reducing the reactivity of the highly reactive lithium powder produced by charging and discharging, so that, when water or the equivalent gets inside the negative electrode when the lithium-air battery is damaged, the water or the equivalent cannot quickly get inside the negative electrode.
    The negative electrode 30 is provided below the solid electrolyte 8 in Figure 1. This negative electrode 30 is fixed by welding the two ends of each of the four sides in the figure which are sandwiched by the laminated films of sheets upper and lower metal sheets 2. In addition, the laminated films of upper and lower metal sheets 2 are welded to the corresponding upper and lower positions of the negative electrode with the heat-sealing materials 10, 10 in between.
    Figure 2 illustrates the protected lithium electrode 1 of Figure 1 in an enlarged manner, and Figure 3 illustrates the negative electrode 30 in Figure 1 in an enlarged manner. As illustrated in FIGS. 1 to 3, the negative electrode 30 has a structure in which five layers are stacked in the order of a film 9, a current collector for a negative electrode with copper foil 3, a layer of negative electrode active material 5 made of lithium metal, a lithium powder fine capture layer 11 which captures the lithium metal fine powder produced during charging and discharging, as will be described later, and a separator 7 from the lower side to the upper side in the figure. Here, the film 9 is a film, for example of polypropylene resin, and covers the lower surface of the negative electrode current collector 3 by assembly by welding. Note that the negative electrode active material layer 5 is sealed by the negative electrode current collector 3 and the separator 7, although this is not shown in Figure 1 and Figure 2 because it s 'is a sectional view. The details of this structure are described below.
    The lithium fine powder capture layer 11 is, for example, a conductive foam or a body formed of metal fibers (metal wool such as copper having a conductivity, or a fabric or a formed body of felt type). Here, sheet-shaped treated wool having a fiber diameter of 0.02 mm or less and a thickness of 2 mm or less is desirable as metal wool of conductive material such as copper wool.
    Here, if the diameter of the fibers of the metal fiber body is greater than 0.02 mm, the area of each fiber of the metal fiber body is considered as a reaction field of the Li deposition reaction. C Therefore, if the diameter of the fibers decreases, the number of reaction fields increases, causing an insufficient effect of the body formed of metal fibers. If the fiber diameter increases, the weight and volume of the metal fiber body increases, affecting the reduction in size and reduction in battery weight (energy density).
    In addition, if the thickness of the metal fiber body is more than 2mm, the following problem occurs. Since this structure is a structure in which the entire negative Li metal electrode comprising the body formed of metal fibers is covered by the bag-shaped separator 7, it is necessary to increase the size of the separator in the form of bag 7 if the thickness of the formed body exceeds 2 mm. In addition, if the metal fiber body has the same fiber diameter and weight, but a different thickness, the porosity inside the metal fiber body is high. In this case, if the separator 7 is large (the space inside the bag is large) and the porosity of the body formed of metal fibers is large, the bubbles are taken inside the protected lithium electrode, which must be filled with an organic electrolyte solution, resulting in an increase in internal resistance.
    The lithium fine powder capture layer 11 can be a felt sheet subjected to wool defibration followed by a needling treatment, rather than a porous metal sheet or a wool-like metal sheet intermingled with fines. conductive metal fibers. The same material as that of the negative electrode current collector is preferably used, but the material may be different as long as the battery operates without problems within the operating range of the battery.
    Here, if the conductive foam is used as a lithium fine powder capture layer 11, there is an advantage in that the thickness of the foam sheet is easily controlled, the foam is filled with lithium during charging, and it is possible to suppress the increase in thickness, for example.
    In addition, if the body formed of metal fibers (fabric or formed body of wool type or felt type) is used as a capture layer of fine lithium powder 11, which has flexibility because it is fibrous , which is restored to its original state if it is folded (does not deform plastically), and which is a fine fiber, there are advantages in that, for example, the specific surface is large, a conductive track is easily established, the amount of fibers is easily increased and decreased, the porosity is easily adjusted, and welding for example by a resistance welding machine is easily performed.
    The separator 7 has a property which allows the passage of the electrolyte, described below, and conducts the lithium ions. In addition, both the left and right end surfaces in the figures of this separator 7 are linked to the negative electrode current collector 3 (see Figure 1 and Figure 3). In addition, the separator 7 is linked to the negative electrode current collector 3 with four linked portions 73 comprising an edge portion on the front side in the figure and an edge portion on the rear side in the figure. Therefore, the layer of negative electrode active material 5 is sealed to an unbound portion 74 which is located on the surface of the negative electrode current collector 3 and which is not bonded to the separator 7. Note that the size of the layer of active material of negative electrode 5 is the same as, or slightly less than, that of the unbound portion 74. As illustrated in FIG. 1, this unbound portion 74 is positioned at a location substantially corresponding to the solid electrolyte 8 provided on the upper side in Figure 1. Due to such a structure, the layer of negative electrode active material 5 is isolated from the solid electrolyte 8 and is not in direct contact with the solid electrolyte 8. It should be noted that a small amount of electrolyte (for example a non-aqueous electrolyte solution, an organic electrolyte solution, or a polymer electrolyte) is sealed in the space between the born electrode current collector gative 3 and the laminated film of metal sheets 2.
    Furthermore, the embodiment has a configuration in which the lithium fine powder capture layer 11 is arranged on the negative electrode active material layer 5 and the negative electrode current collector 3 on the inner side of the separator 7, one of the edge portions is linked to have an electrical conductivity, and the layer of negative electrode active material 5 is completely covered by the separator 7 from above. It is therefore possible to confine the lithium powder formed into a fine powder by charging and discharging, between the separator 7 and the negative electrode current collector 3. While preventing direct contact between the solid electrolyte 8 and the negative electrode 30, this makes it possible to eliminate the dispersion and the leakage inside the protected lithium electrode 1 of the fine lithium powder produced during the charge and discharge cycle, to reduce the fine lithium powder which does not contribute to charging or discharging, delaying the degradation of the solid electrolyte 8, resulting in an extension of the life of the cell and an improvement in safety. Furthermore, when the fine lithium powder capture layer 11 is bonded to have an electrical conductivity inside the bag of the separator 7, it is possible to improve the utilization rate of the fine lithium metal powder produced. by charging and discharging to obtain more lithium which contributes to charging and discharging, and to improving a charge and discharge property under these effects.
    A description is provided here for the case where the protected lithium electrode 1 of Figure 1 is used for a lithium-air battery. In this case, an air electrode (not shown) is used which is installed above the solid electrolyte 8 in the figure. When the lithium-air cell using this protected lithium electrode 1 discharges, the layer of negative electrode active material 5 (lithium metal) used for the negative electrode 30 is divided into lithium ions (Li + ) and electrons ( e), as illustrated in Chemical reaction 1. Then, the lithium ions (Li + ) dissolve in the electrolyte solution, and the electrons (e) are supplied by an electron collecting part 31 of the collector of negative electrode current 3 at a terminal portion 32. It is therefore possible to control the design value of the capacity of the battery by changing the thickness and the surface of the layer of active material of negative electrode 5.
    Chemical reaction 1
    Li Li + + e '
    In addition, the positive electrode (not shown) receives electrons, where ambient oxygen and water react with each other to produce hydroxide ions (OH) (Chemical reaction 2). In addition, these hydroxide ions (OH) react with lithium ions (Li + ) at the positive electrode to produce Γ lithium hydroxide (LiOH).
    Chemical reaction 2
    O 2 + 2H 2 O + 4th 4OH “
    On the other hand, when this lithium-air cell is charged, the lithium ions supplied by the positive electrode pass through the solid electrolyte 8 and the separator 7 to reach the surface of the electron collecting part 31 of the current collector. negative electrode 3 in the negative electrode 30, and the lithium metal deposition reaction occurs accordingly (Chemical reaction 3).
    Chemical reaction 3
    Li + + e 'Li
    Here, as illustrated in FIG. 3, the separator 7 is linked to the electron collecting part 31 to the linked portions 73. This is why the surface of the electron collecting part 31 is not exposed to the bonded portions 73, and the lithium metal deposition reaction does not occur. The lithium metal deposition reaction therefore takes place only in the unbound portion 74 of FIG. 4.
    As illustrated in FIG. 4, the rear surface of the electron collecting part 31 is covered with the film 9. This is why the electrolyte solution does not reach the rear surface of the electron collecting part. electrons 31, and therefore the lithium metal deposition reaction does not occur.
    If the rear surface of the electron collecting part 31 is not covered by the film 9 contrary to the above, the dendrite is deposited on this rear surface. The fine lithium produced when the ends of this dendrite break is dispersed in the electrolyte solution. Since this thin dispersed lithium does not contribute to the charging or discharging, the charging and discharging performance of the lithium-air cell decreases accordingly.
    On the other hand, the protected lithium electrode structure according to the embodiment can provide a high-performance lithium-air battery by suppressing the production of this dead lithium.
    At the same time, at the positive electrode, an oxygen-producing reaction indicated by Chemical Reaction 4 takes place.
    Chemical reaction 4
    4OH 'O 2 + 2H 2 O + 4th
    A description is provided below for the materials constituting the parts used for the first embodiment.
    Polyolefin based resins such as polypropylene resins and polyethylene resins can be used as the resin layer 21 in the laminated film of metal sheets 2. These resins have low melting points, are easy to heat treat , and are suitable for heat sealing (thermal bonding), facilitating the manufacture of the protected lithium electrode 1.
    In addition, the laminated metal foil film 2 is provided with the metal foil layer 22 to improve the barrier property against gases and resistance. It is possible to use a metal sheet such as aluminum sheet, stainless steel sheet, and copper sheet for the layer of metal sheets 22.
    Finally, as the resin layer 23, it is possible to use nylon-based resins and polyester-based resins such as polyethylene terephthalate resins. These resin materials exhibit excellent thermal and thermal resistance. It is therefore possible to improve durability, thermal resistance, resilience, etc. of the protected lithium electrode 1.
    Although the laminated metal sheet film 2 has a three-layer structure in the first embodiment, the laminated metal sheet film 2 may have a structure with four or more layers in which one or more resin films such as 'a nylon film are stacked between layers.
    For example, a glass ceramic, which is non-flammable and has excellent conductivity of lithium ions, can be used as a solid electrolyte 8. In particular in the case where an aqueous electrolyte solution is used as the electrolyte solution, it is possible to use a LATP-based glass ceramic electrolyte with high water resistance. LATP is an oxide having a crystal structure of the NASICON type which comprises, for example, Li, Ti, Al, P, Si, and O.
    As the film 9, for example, it is possible to use a resin sheet, such as polypropylene and polyethylene, which is resistant to an electrolyte solution (organic electrolyte solution). Note that the film 9 is bonded over the entire rear surface of the electron collecting portion 31 of the negative electrode current collector 3. However, only the peripheral edge portions can be bonded. What is more, not only the rear surface, but also the side surfaces (edge portions) of the negative electrode current collector 3 can be covered.
    The separator 7 can be a sheet of cellulose or of resin based on polyolefin such as polyethylene or porous polypropylene used as separator for a lithium ion battery, for example. The materials include, in addition to these, aramid and polytetrafluoroethylene before a porous structure. It is possible to use the above separator impregnated for example with an electrolyte solution (non-aqueous electrolyte solution, organic electrolyte solution) or with a polymer electrolyte.
    In addition, it is possible to use the separator 7 with a porosity of about 40% to 90% and a thickness of about 10 to 300 µm, preferably about 15 to 100 µm. The size of each pore can be from about 20 nm to 500 nm, preferably from about 20 to 70 nm. Furthermore, it is preferable that the separator 7 itself has a certain degree of rigidity and resistance.
    Regarding the electrolyte solution, for example, as a non-aqueous electrolyte solution, it is possible to use a mixed solvent of organic solvent based on carbonate ester containing PC (propylene carbonate), EC (ethylene carbonate), DMC (dimethyl carbonate), or EMC (ethyl methyl carbonate), or an ether-based solvent such as ethylene glycol dimethyl ether, dimethyl ether of tetraethylene glycol, and the dimethyl ether of triethylene glycol, added with an electrolyte such as LiPFf (lithium hexafluorophosphate), LiClCL (lithium perchlorate), LiBp4 (lithium tetrafluoroborate), LiTFSI (bis (trifluoromethanesulfonyl) lithium imide), and LiFSI (lithium bis (fluorosulfonyl) imide). As an aqueous electrolyte solution, for example such as a lithium salt to be dissolved in water, it is possible to use LiCl (lithium chloride), LiOH (lithium hydroxide), L1NO3 ( lithium nitrate), and CH3COOL1 (lithium acetate), or a mixed solution thereof.
    It should be noted that the positive electrode (not shown) can be, for example, a catalytically active noble metal such as platinum, gold, iridium, or ruthenium, an oxide thereof, or an oxide of catalytically active metal such as catalytically active manganese dioxide having a large specific surface, mixed with an electrically conductive agent such as highly conductive carbon and, as a binder, polyvinylidene fluoride, polytetrafluoroethylene, rubber styrene-butadiene, etc., and supported on an air electrode current collector having a conductivity and a gas dispersing property. For example, for this air electrode current collector, it is possible to use carbon paper, carbon fabric, carbon nonwoven fabric, titanium lattice, nickel lattice, copper, a stainless steel mesh, porous nickel (nickel metal foam), and a metal mesh in which a highly corrosion-resistant metal such as nickel, titanium, or stainless steel is used. It should be noted that the carbon fabric mentioned here refers to a fabric type sheet woven with, for example, carbon fibers, and the nonwoven carbon fabric indicates sheet-like carbon fibers woven randomly with each other. other. Note that if an aqueous electrolyte solution is used for the electrolyte solution, the air electrode current collector must also be resistant to corrosion by the electrolyte solution. It is therefore possible to preferably use, for example, carbon fibers which have a high conductivity, are resistant to corrosion by both acid and alkaline solutions, and are light in weight.
    Figure 4 illustrates an example of the negative electrode 30 in the first embodiment and is a diagram of the negative electrode seen from above in Figure 2. The current collector of the negative electrode 3 comprises the collecting part of electrons 31 positioned on the left side in the figure and the terminal portion 32 positioned on the right side in the figure. The electron collecting part 31 has the shape of a quadrilateral with a larger surface than that of the terminal portion 32. The electron collecting part 31 has the layer of active material of negative electrode 5 and the separator 7 stacked therein. In the negative electrode 30, a sheet of the negative electrode active material layer 5 which is a lithium metal and is smaller than the surface of the negative electrode current collector 3 is bonded to the current collector. negative electrode 3 which has a structure in which the electron collecting part 31 and the terminal portion 32 formed for example from a copper foil are integrated. In addition, on the negative electrode active material layer 5, an edge portion of the lithium fine powder capture layer 11 is bonded to a bonded portion 12 to one side of the negative electrode current collector by the resistance welding machine. On this portion is placed the separator 7 which is a thermoplastic resin such as polyethylene or porous polypropylene often used in a lithium ion battery so as to cover these elements. The separator 7 is bonded by welding to the bonded portions 73, namely the four sides of the peripheral edge portion, where the layer of active negative electrode material 5 positioned on the surface of the negative electrode current collector 3 and the lithium fine powder capture layer 11 are not arranged. In addition, the rear surface of the electron collecting portion 31 of the negative electrode current collector 3 is completely covered with the film 9 (see Figure 1). This film 9 is also preferably a resin sheet which does not allow an electrolyte solution to pass through and is resistant to degradation by an electrolyte solution, for example a resin sheet resistant to an organic electrolyte solution , such as polypropylene or polyethylene. In this example, the lithium fine powder capture layer 11 is bonded to the copper foil of the negative electrode current collector 3 with, for example, a spot welding machine. This bonded portion is indicated with the reference 12 and is a portion in which an edge portion of the lithium fine powder capture layer 11 and the copper foil of the negative electrode current collector 3 are stacked one on the other. the other. It should be noted that in FIG. 4, the reference 13 indicates a thermal bonding sheet used to thermally weld the separator 7 and the copper sheet of the negative electrode current collector 3.
    Figures 5A and 5B show another example of the negative electrode 30 in the first embodiment. In this example, the separator 7 has bonded portions 75 on both ends, on which portions of the thermal bonding sheets 14, 14 are placed and bonded, as shown in Figure 5B. The negative electrode 30 illustrated in Figure 5A is formed by: folding a separator 7 illustrated in Figure 5B along a fold 7a close to the center thereof to form a mountain fold; performing a heat seal to the thermal bonding portions 76, namely two peripheral edge portions to give the separator a bag shape; placing a single unit of the negative electrode active material layer 5 and the negative electrode current collector 3 in the bag; then thermal welding of the thermal bonding portions 76 together to close the bag, thermal welding of the separator 7 to the copper foil of the negative electrode current collector 3, and bonding of the thermal bonding sheets 14, 14 to the bonded portion 77 next to the tied portion 75 to close the bag more tightly. In the negative electrode 30 having such a configuration, it is possible to obtain the same effects as those of the negative electrode 30 in FIG. 4. It should be noted that the thermal bonding sheet which is interposed between the separator 7 and the copper sheet of the negative electrode current collector 3 and is used to bond these elements is preferably a thermal bonding sheet based on acid-modified polypropylene.
    Second embodiment
    Using Figure 6, a description is provided for a protected lithium electrode structure for a lithium-air battery according to a second embodiment. Note that the second embodiment is a modification of the first embodiment illustrated in Figures 1 to 4, the repeated explanation is omitted and only the differences are explained.
    A protected lithium electrode 1 illustrated in Figure 6 has a configuration in which an opening portion 4 of a solid electrolyte 8 of the protected lithium electrode is provided on each side of the battery. The protected lithium electrode 1 in this second embodiment has a structure in which a layer of negative electrode active material 5, a layer of fine lithium powder capture 11, a separator 7, a solid electrolyte, and a laminated film of metal sheets 2 are provided on each side, upper and lower, with a negative electrode current collector 3 as a border.
    Such a structure makes it possible to omit a film 9 covering the rear surface of the negative electrode current collector 3 and the laminated film of metal sheets 2 covering the rear surface of the protected lithium electrode 1, and to reduce the volumes and the weights of the protected lithium electrode 1 and of a lithium-air battery using it compared to a structure in which the battery is sealed in a container with a surface of an air electrode facing a surface d '' a protected lithium electrode 1.
    In addition, unlike the upper covering material of the opening portion 4 of the solid electrolyte 8 of the protected lithium electrode 1 (corresponding to the laminated film of upper metal sheets 2), the opposite side (corresponding to the film lower metal foil laminate 2) may have a structure in which the negative electrode active material layer 5 is bonded to a copper foil portion of a two layer structure laminate film of copper foil / PET resin , and the negative electrode 30 is covered by the separator 7, namely the porous resin sheet of the present proposal. This configuration makes it possible to supply the copper foil of the laminated film of metal foils 2, namely a covering material, as a negative electrode current collector 3, and to reduce the number of parts and the thickness and weight of the battery.
    Other embodiments
    The above descriptions of embodiments are examples intended to explain the protected lithium electrode structure for the lithiumair cell according to the present invention and are not intended to limit the invention claimed in the claims. In addition, the configuration of each component of the present invention is not limited to the embodiments described above and can be varied in various ways within the technical scope described in the claims.
    For example, in the embodiments described above, the lithium fine powder capture layer 11, the layer of negative electrode active material 5, the negative electrode current collector 3, the solid electrolyte 8 , etc., do not have to be rectangular or square. The shape can be changed to a circular or polygonal shape depending on the intended use. In addition, a protected lithium electrode does not necessarily need to have a layer of negative electrode active material 5, but may have more than one layer of active negative electrode material 5. In addition, the protected lithium electrode does not need to be flat, but can be modified according to the intended use. For example, the protected lithium electrode may be of a three-dimensional shape.
    It should be noted that the capture layer of fine lithium powder 11 may be a sheet formed like wool using the same material as that of the negative electrode current collector 3, for example copper, stainless steel, and the Ni. There is a phenomenon in which, when different metals are in contact with each other, corrosion of one of the metals (the metal with the greatest tendency to ionize) is generally favored due to the difference in tendency to ionization (galvanic corrosion). However, if the two metals are of the same material, there is an advantage in that the degradation of the cell can be delayed, since no galvanic corrosion occurs. Although it is necessary to bond the fine lithium powder capture layer 11 and the negative electrode current collector 3 together by means of resistance welding, for example with a spot welding machine in order to establish an electrical conductivity, it is difficult to bond different metals together even when using such welding means. However, if the lithium fine powder capture layer 11 and the negative electrode current collector 3 are of the same material, they are easily bonded because the above problem is eliminated. Therefore, there is an advantage in that productivity is improved.
    Example 1
    Below, an example is shown below in which a charging and discharging experiment has been carried out for the lithium-air cell by adopting a protected lithium electrode structure 1 according to the first embodiment.
    First, a description is provided for a protected lithium electrode 1 (see Figure 1 and Figure 7) used in Example 1, a positive electrode, and a method of manufacturing a lithium-air battery using them.
    In this example, a laminated film of metal sheets 2 was used which comprises the resin layer 21 made of a PP resin (polypropylene), the metal sheet layer 22 of Al sheet (aluminum), and the resin layer 23 of PET resin (polyethylene terephthalate). An opening portion 4 was provided by drilling a hole of 2 square centimeters in the central portion of this laminated film of metal sheets 2. Next, a polypropylene film modified with perforated acid (outer peripheral portion: 3 centimeters square; inner periphery:
    square centimeters), a solid electrolyte 8 of 2.5 square centimeters (LATP), and a polypropylene film modified with perforated acid (outer peripheral portion:
    square centimeters; inner periphery: 2 square centimeters) were stacked on top of each other in this order under the laminated film of metal sheets 2. Then the four sides of solid electrolyte 8 were heat sealed and bonded using with a heat sealer so as to close the opening portion 4. Next, an adhesive sheet (polypropylene film modified with perforated acid (outer peripheral portion: 3 square centimeters; inner periphery: 2 square centimeters)) was inserted between each of the two layers, and the four sides of the solid electrolyte 8 were heat sealed and bonded to the laminated film of metal sheets 2 using a heat sealer.
    At the same time, the negative electrode 30 (see Figure 3) was fabricated inside a glove box under an argon atmosphere. First, a negative electrode current collector 3 was prepared (copper foil thickness: 10 μιη; size of the current collector: 3 cm x 7 cm) in which a polypropylene film modified with acid has been bonded to the back surface. Next, a layer of copper wool to capture fine lithium powder 11 (produced in the form of a sheet of the following dimensions: 1.45 cm × 2 cm; fiber diameter: 0.02 mm or less; and thickness : 2 mm or less) has been stacked on a central surface portion of a 3 square centimeter portion of the end portion. The edge portion on the terminal side of the negative electrode current collector 3 and one side of the lithium fine powder capture layer 11 have been bonded using a micro-spot welding machine, and were then covered with a polypropylene resin separator 7 for a lithium ion battery. The four sides of the edge portions have been heat sealed and bonded to a portion where the polypropylene of the rear surface of the negative electrode current collector 3 has been bonded, and the negative electrode 30 has thus been formed integrally (Figure 7 and Figure 8). Note that in Figures 1 to 3 and in Figure 6, reference 12 indicates a bonded portion where the lithium fine powder capture layer 11 and the copper foil of the negative electrode current collector 3 are welded with, for example, a spot welding machine.
    The upper metal foil laminate 2, the negative electrode 30, and the lower metal foil laminate 2 (without the solid electrolyte opening portion 4) were stacked on top of each other so that the solid electrolyte 8 and the layer of negative electrode active material 5 on the negative electrode current collector 3 were located at the corresponding positions. Next, three sides of the peripheral portion were heat sealed and bonded using a heat sealer. In addition, 1 ml of non-aqueous electrolyte solution (4 M (mol / 1) LiFSEEGDME) was injected through the unbound side remaining inside the protected lithium electrode. Then, after letting the interior gas out, the remaining side of the edge portion (end portion 32 of the negative electrode current collector 3) was finally bonded with a heat sealer and closed. The protected lithium electrode 1 in Figure 3 was thus fabricated.
    It should be noted that LATP (LICGC manufactured by OHARA INC.) Was used as a solid electrolyte. In addition, the separator used for the lithium ion cell was made from a polypropylene resin and had a thickness of 25 qm, an average pore diameter of 0.03 qm or less, a porosity of 44%, and a permeability of 450 s / 100 cc.
    Next, a positive electrode (not shown) was fabricated. First, 0.8 g of MnCE (specific surface of approximately 300 m 2 / g) as a positive electrode catalyst, 0.1 g of Ketjen black (specific surface of approximately 800 m 2 / g) as an electrically conductive agent, and 0.1 g of polytetrafluoroethylene (PTFE) as a binder were prepared. These, supplemented with 5 ml of ethanol as a dispersant, were mixed in an agate mortar to create a positive electrode material.
    Then, the positive electrode material was divided into two equal portions which were arranged on the two surfaces of a compression connection portion of Ti lattice having fully one unit of a compression connection portion of 2, 5 x 2.5 cm 2 and a terminal portion of 1 x 5.5 cm 2 , then bonded by compression with a force of 20 kN. The product obtained was dried naturally for 24 hours to prepare a positive electrode structure. Then, a lithiumair battery was made with the protected lithium electrode 1 and the positive electrode facing each other. The aqueous electrolyte solution on the positive electrode side used was a mixed liquid of LiOH and LiCl. An aqueous electrolyte solution was prepared in which 1.5 M (mol / L) of aqueous LiOH solution and 10 M (mol / L) of aqueous LiCl solution were mixed in a 1: 1 ratio of so the pH was 10 or less. It should be noted that in order to retain the aqueous electrolyte solution, 1.5 ml of the solution were deposited on the 3 cm square polyacrylamide sheet and arranged between the protected lithium electrode 1 and the positive electrode.
    Figure 9 and Figure 10 illustrate a negative electrode 30 used to make performance comparisons with the negative electrode 30 illustrated in Figure 7 and Figure 8. Fa Figure 9 is a plan view and Figure 10 is a view from below of the negative electrode 30. As for the negative electrode 30 illustrated in Figure 9 and Figure 10, the elements having the same functions as those illustrated in Figure 7 and Figure 8 are given the same references, and the repetitive explanations are omitted. The negative electrode 30 illustrated in Figure 9 and Figure 10 differs from the negative electrode 30 illustrated in Figure 7 and Figure 8 only in that it does not include the lithium fine powder capture layer 11.
    Below, a description is provided for a discharge and load test in Example 1.
    First of all, the lithium-air battery manufactured as described above was charged for five hours at 4 mA (which corresponds to a current density of 2 mA / cm 2 in terms of surface of copper wool) to be adjusted to a negative electrode capacity corresponding to 20 mAh. Fa Figure 11 illustrates a result of the voltage change at a temperature of 25 ° C when the charge and discharge were repeated for one hour at 4 mA (which corresponds to a current density of 2 mA / cm 2 in terms of copper wool surface), the same value as above, which was measured with HJ1001SD8 manufactured by Hokuto Denko Corporation. Consequently, the discharge was stopped in the fifteenth cycle in the comparative example illustrated in FIG. 9 and in FIG. 10, while on the other hand the charge and the discharge continued for 56 cycles in Example 1 illustrated in the Figure 7 and Figure 8, which means that the charge and discharge cycle property has been improved.
    Of course, the invention is not limited to the exemplary embodiments described and shown above, from which other modes and other embodiments can be provided, without going beyond the ambit of the invention.
    List of references protected lithium electrode laminated film of metal sheets negative electrode current collector opening portion layer of negative electrode active material solid electrolyte separator film heat sealing material (thermal bonding sheet) capture layer fine lithium powder bonded portion heat sealing material (thermal bonding sheet) heat sealing material (thermal bonding sheet) resin layer metal sheet layer resin layer resin layer negative electrode electron collecting part terminal portion tied portion unbound portion tied portion thermal bonding portion tied portion
    权利要求:
    Claims (7)
    [1" id="c-fr-0001]
    1. Protected lithium electrode structure for a lithium-air battery, comprising: a negative electrode current collector (3);
    a layer of negative electrode active material (5) which consists of a lithium metal, an alloy containing mainly lithium, or a compound containing mainly lithium and which is stacked on the negative electrode current collector (3 ); and a separator (7) stacked on the layer of active material of negative electrode (5), in which the layer of active material of negative electrode (5) is sealed by the separator (7) and the current collector negative electrode (3), and a lithium fine powder capture layer (11) which captures the lithium metal fine powder produced during charging and discharging is provided between the layer of negative electrode active material (5) and the separator (7), and has an electrical conductivity by means of a bonding on one side of the capture layer of the fine lithium powder (11).
    [2" id="c-fr-0002]
    2. Protected lithium electrode structure for a lithium-air cell according to claim 1, wherein the lithium fine powder capture layer (11) is a conductive foam or a body formed of metal fibers.
    [3" id="c-fr-0003]
    3. Protected lithium electrode structure for a lithium-air cell according to claim 1 or 2, in which the lithium fine powder capture layer (11) is made of the same material as that of the electrode current collector. negative (3).
    [4" id="c-fr-0004]
    4. Protected lithium electrode structure for a lithium-air cell according to claim 2, wherein the body formed of metal fibers is a fabric or a body formed of wool type or felt type.
    [5" id="c-fr-0005]
    5. Protected lithium electrode structure for a lithium-air cell according to any one of claims 1 to 4, in which the separator (7) is linked to the negative electrode current collector (3) to a portion of peripheral edge of the negative electrode active material layer (5).
    [6" id="c-fr-0006]
    6. Protected lithium electrode structure for a lithium-air cell according to any one of claims 1 to 5, in which the negative electrode current collector (3) has a sheet or plate shape, the layer of negative electrode active material (5) is arranged on a surface of the
    10 negative electrode current collector (3), and another surface of the negative electrode current collector (3) is covered with a substance having a non-conductance of lithium ions.
    [7" id="c-fr-0007]
    7. Protected lithium electrode structure for a lithium-air battery according to one
    15 of any of claims 1 to 6, wherein the layer of negative electrode active material (5) is stacked on a surface of the negative electrode current collector (3) so as to cover an area smaller than the surface of the negative electrode current collector (3).
    1/4
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    US10784503B2|2020-09-22|
    CN108539204A|2018-09-14|
    JP2018147572A|2018-09-20|
    DE102018104635A1|2018-09-06|
    FR3063576B1|2022-01-14|
    JP6853504B2|2021-03-31|
    US20180254474A1|2018-09-06|
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    法律状态:
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    优先权:
    申请号 | 申请日 | 专利标题
    JP2017038307|2017-03-01|
    JP2017038307A|JP6853504B2|2017-03-01|2017-03-01|Negative electrode composite structure of lithium-air battery|
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