JP5661550B2 - Secondary battery unit and assembled secondary battery - Google Patents

Description

  The present invention relates to a solid electrolyte separator, a secondary battery unit, and an assembled secondary battery.

Patent Document 1 (US2009 / 0061288
A1) uses a thin Li conductive ceramic dense body as a separator in a LiS (lithium-sulfur) secondary battery. In LiS batteries using electrolyte, the positive electrode polysulfide elutes into the electrolyte, and the positive electrode eluted in the electrolyte migrates (moves) to the negative electrode and can be charged and discharged as the charge / discharge cycle is repeated. There is a problem that capacity gradually decreases. For this reason, a method of suppressing migration (migration) of the positive electrode polysulfide to the negative electrode by applying a dense ceramic film having Li ion conductivity to the separator portion is disclosed. Further, LISICON (Li1 + xAlxTi2-x (PO4) 3 (x = 0.0 to 0.5)) is disclosed as a ceramic dense body to be used. Also disclosed is a configuration in which a porous reinforcing membrane that allows electrolyte to penetrate is sandwiched between both sides of LISICON for mechanical strength reinforcement.

Patent Document 2 (US2008 / 0268327
A1) discloses a configuration in which a solid electrolyte separator is applied to a water-based metal-air battery. It is an ion conductive solid electrolyte separator having a dense layer in the center and a structure in which both sides thereof are sandwiched between porous layers provided to prevent damage to the dense layer. Solid electrolyte material with NASICON structure such as Li1-xMxTi2 (PO4) 3 (x = 0-1.5, M = Al, Zr, Sn, Hf, Y) should be provided in the dense layer. Is disclosed.

  In Patent Document 3 (WO 2008-059987), a solid electrolyte structure in which a porous solid electrolyte layer is formed on both sides of a dense solid electrolyte plate, and an all-solid battery in which an electrode material is accommodated in the porous solid electrolyte layer Is disclosed.

Patent Document 4 (Japanese Patent Application Laid-Open No. 2011-73962) discloses a specific ceramic material having a garnet crystal structure as a solid electrolyte material of a lithium secondary battery.

  Furthermore, the all-solid-state energy storage device described in Patent Document 5 (Japanese Patent Application Laid-Open No. 2008-078119) discloses a solid electrolyte separator having concave portions that accommodate positive and negative electrodes. Generally, in an all-solid-state power storage element, it is necessary to reduce internal resistance by increasing the contact area between an electrode active material and an electrolyte in order to improve battery output characteristics. However, on the other hand, the resistance of the electrolyte layer decreases as the junction area becomes thinner, but the strength decreases when a thin and wide area of the electrolyte layer is formed. For this reason, the contact areas between the electrodes and the solid electrolyte are increased by arranging the recesses accommodating the electrode portions alternately or in a staggered manner in the solid electrolyte separator, and at the same time, the solid electrolyte is made thinner.

US2009 / 0061288A1 US2008 / 0268327A1 WO 2008-059987 JP2011-73962A JP2008-078119

  In Patent Document 1 and Patent Document 2, a reinforcing film is added because the ceramic dense film is a thin plate and it is difficult to maintain the strength. However, this is a factor that decreases the energy density of the battery. Recently, a battery design that reduces the weight of the battery case and improves the energy density by stacking in series or in parallel in one unit of the battery may be performed. However, in this configuration, an electrolyte liquid junction occurs. Therefore, it is necessary to connect the batteries individually, and stacking in the unit is not possible. As another means for improving the energy density, a method of enlarging the battery can be considered, but in this case, the problem of the substrate strength becomes more obvious and the enlarging is impossible.

  In addition, LISICON (Li1 + xAlxTi2-x (PO4) 3 (x = 0.0 to 0.5)), Li1-xMxTi2 (PO4) 3 (x = 0-1.5, M = Al, Zr, Sn, Hf, Y) etc. The solid electrolyte material having the NASICON structure is reduced at the lithium potential when Li dendrite is generated at the negative electrode because the potential window on the reduction side is narrow. For this reason, the solid electrolyte is degenerated, and in some cases, electronic conductivity is generated in the solid electrolyte, and there is a possibility that a short circuit occurs between the positive and negative electrodes.

  Batteries are required to have both excellent energy density and power density characteristics. Therefore, not only is the electrode filling efficiency good, but the low internal resistance of the battery is one of the excellent battery conditions. is there. In the solid electrolyte separator described in Patent Document 5, lithium ions move between the positive electrode and the negative electrode, that is, through the partition walls (side walls) of the recesses of the solid electrolyte separator. That is, lithium ions move in the horizontal direction when the separator is viewed in plan. Therefore, one of the measures for reducing the resistance on the ion conduction surface is to increase the opposing area between the positive and negative electrodes. For this purpose, it is necessary to deepen the electrode housing recess. However, in that case, electrons are conducted in the thickness direction of the separator. Therefore, if each recess is deepened, the conductive distance to the current collector is increased, so that the resistance is increased in terms of electron conduction. In terms of the manufacturing method, it is not preferable to form (insert) each electrode layer in each recess because the technical difficulty level increases.

  In order to improve the energy density of the battery, it is necessary to design the electrode with a high accommodation density. However, on the other hand, in order to improve the output density, it is necessary to design the electrode to be thin. Therefore, it is desirable that the electrode layer has a wide and thin structure. Therefore, a ceramic separator made of a solid electrolyte is required to have a large area and a thin plate shape. However, it requires tough strength, and the conventional design has a limit in achieving both large area and low resistance.

  An object of the present invention is to reduce both resistance to ionic conduction and resistance to electronic conduction in a secondary battery in which each electrode is partitioned by a dense solid electrolyte separator having ionic conductivity, making it easy to accommodate each electrode. It is to provide a solid electrolyte separator and a battery using the solid electrolyte separator.

The present invention is a secondary battery unit comprising a solid electrolyte separator ,
The separator is formed of a dense solid electrolyte having ion conductivity for a secondary battery, the first electrode and the second electrode of the secondary battery are divided, and the separator is a plate-like ion conductive portion, A first partition wall protruding from the ion conductive portion toward the first main surface side, a second partition wall protruding from the ion conductive portion toward the second main surface side, and opening to the first main surface side; A first recess for accommodating the first electrode, and a second recess for opening the second electrode and opening the second main surface, and including a periphery of the first recess. At least a portion is divided by the first partition, at least a portion of the periphery of the second recess is partitioned by the second partition, and the first electrode is a negative electrode,
The secondary battery unit is
A first current collector that covers the first recess, blocks ion conduction, and has electron conductivity;
A second current collector that covers the second recess, blocks ionic conduction, and has electronic conductivity; and
A metal film is provided on the inner surface of the first recess, and the metal film functions as an electron conduction path to the first current collector .

The present invention also provides:
An air battery unit comprising a solid electrolyte separator,
The separator is formed of a dense solid electrolyte having ion conductivity for a secondary battery, the first electrode and the second electrode of the secondary battery are divided, and the separator is a plate-like ion conductive portion, A first partition wall protruding from the ion conductive portion toward the first main surface side, a second partition wall protruding from the ion conductive portion toward the second main surface side, and opening to the first main surface side; A first recess for accommodating the first electrode, and a second recess for opening the second electrode and opening the second main surface, and including a periphery of the first recess. At least a portion is divided by the first partition, at least a portion of the periphery of the second recess is partitioned by the second partition, and the first electrode is a negative electrode,
The air battery unit is
A current collector that covers the first recess, blocks ion conduction, and has electron conductivity;
An oxygen permeable membrane covering the second recess, and
A metal film provided on an inner surface of the first recess is provided, and the metal film functions as an electron conduction path to the current collector .

  The present invention also relates to an assembled secondary battery, wherein a plurality of the secondary battery units are stacked.

  According to the present invention, the first electrode is formed in the first recess opening in the first main surface of the separator, and the second electrode is accommodated in the second recess opening in the second main surface of the separator. To do. And from the ion conduction part which isolate | separates a 1st recessed part and a 2nd recessed part, a 1st partition is protruded on the 1st main surface side, and a 2nd partition is protruded on the 2nd main surface side.

  Thereby, the ionic conduction between the first electrode and the second electrode is carried by the ion conducting portion extending in the separator surface direction. Therefore, even if each concave portion is shallow, the area between both poles does not change, so that the ionic conductivity in this portion does not decrease. On the other hand, since the conductive distance in the thickness direction of the separator is shortened in the electrode layer accommodated in the recess, both ion conductivity and electron conductivity in the electrode layer can be improved. As described above, the structure of the present invention is a ceramic separator structure that can improve both ion conductivity and electron conductivity in the electrode housing portion in a well-balanced manner while using a solid electrolyte separator in a secondary battery. In addition, since it is not necessary to deepen the recesses in order to enlarge the opposing area between the positive and negative electrodes, it is easy to accommodate the electrodes in the respective recesses.

  On the other hand, in the battery structure described in Patent Document 5, ions move in the surface direction of the separator, and electrons move in the thickness direction of the separator. For comparison, for example, the volume of the electrode housing recess is made constant to ensure a constant energy density. Then, as a design of the electrode housing part that reduces the internal resistance of the battery, it is preferable because the ion movement distance (diffusion distance) in the plane direction can be reduced by reducing the area of the opening, but on the other hand, the electrode housing part is deepened. Since it is necessary to design, it becomes difficult to form a current collection (electron conduction path) at the deepest portion, and the difficulty of the manufacturing method for accommodating the electrode to the deepest portion is increased.

On the contrary, when the opening of the accommodating portion is designed to be wide and shallow, the manufacturing method for accommodating the electrode layer is facilitated and the distance of electron conduction is shortened, while the ion conduction distance (diffusion distance) is increased.
In other words, it has been difficult to achieve both a battery design that reduces the internal resistance of the battery by shortening the distance traveled by both ions and electrons, and a design that facilitates the manufacturing method of housing the electrode layer.

  Preferably, the partition wall serving as a beam provided for reinforcement in order to form the opposing portion between the positive and negative electrodes in a thin and large area, the partition wall on the first main surface side when viewed in the thickness direction of the separator. By providing at the position where the partition on the second main surface side overlaps, when the battery units are stacked, they can be joined via the partition. In general, electrode materials are known to repeatedly expand and contract during charging and discharging, and the entire electrode does not always expand and contract evenly depending on the method of using the battery. In addition, high-capacity active materials (for example, solid solution systems, layered oxide systems, sulfur-based cathodes, alloy systems, and negative electrodes such as lithium metals) that are attracting attention as further capacity increases are expected. Further expansion is expected. From such a background, when the battery units are laminated with an electrode active material, the ceramic separator becomes more susceptible to local stress strain as the number of stages increases, and the possibility of breakage increases. However, if the battery units can be stacked and connected via the partition made of a solid electrolyte, the influence of expansion and contraction of the electrode active material can be avoided.

  Here, it is preferable that the first partition wall and the second partition wall are each formed as an elongated protrusion (beam or stripe) along the outer edge of the separator. The partition wall is at a position overlapping with the separator in the thickness direction. In this case, a 1st partition and a 2nd partition may exist in the position which overlaps over the perimeter of a separator along an outer edge.

  Preferably, the first partition wall and the second partition wall existing on the inner side from the outer periphery of the separator are formed as elongated protrusions (beams or stripes), respectively. The partition walls overlap with each other when viewed in the thickness direction of the separator. Thereby, the structural strength of the separator can be further increased.

  In a preferred embodiment, one electrode or both electrodes include a solid electrode material and an electrolytic solution impregnated in the electrode material. In this case, the above-described effects such as expansion and contraction of the electrode are large, and the present invention is particularly suitable. Such electrodes will be described in detail later.

(A) is a perspective view of the solid electrolyte separator 1, and (b) is a perspective view showing one section of the separator 1. (a) is sectional drawing which shows 1 division of the separator 1, (b) shows the state which formed the electrode in the recessed part of the separator 1, (c) is each current collection on each main surface side of a separator, respectively. The state which provided the part is shown. (A) is a perspective view which shows the state which formed the current collection part on each main surface of a separator, (b) is a perspective view which shows the 1 division. (A), (b), (c) is sectional drawing which respectively shows a secondary battery unit. It is a disassembled perspective view which shows typically the assembled secondary battery 20 which laminated | stacked the secondary battery unit 11 of Fig.4 (a). FIG. 6 is a cross-sectional view schematically showing the assembled secondary battery in FIG. 5. It is sectional drawing which shows the specific example of a secondary battery unit. It is a figure which shows typically the assembly secondary battery which laminated | stacked the secondary battery unit of FIG. (A), (b), (c) is a perspective view which shows each separator, respectively. (A) is a perspective view which shows the separator 31 for air batteries which concerns on other embodiment, (b) is a perspective view which shows 1 division of the separator 31. FIG. (A) is a perspective view which shows the state which formed the electrode and the current collection part in the separator 31, (b) is sectional drawing of (a). It is a perspective view which shows the state which laminated | stacked the separator 31. FIG. It is sectional drawing which shows the state which laminated | stacked the secondary battery unit 41, and was seen in the XIII direction of FIG. It is sectional drawing which shows the state which laminated | stacked the secondary battery unit 41, and was seen in the XIV direction of FIG. The 3 is a perspective view showing a state in which an oxygen permeable membrane 50 is formed at a gas port of an assembled battery using a separator 31. FIG. It is sectional drawing which shows the assembled battery of FIG. The specific example of an air battery unit is shown.

1 to 6 relate to a reference embodiment.
As shown in FIG. 1, the separator 1 is formed with a plurality of sections A. The separator 1 is provided with a plate-like ion conducting portion 4, and partition walls 3 </ b> A and 3 </ b> B are formed from the ion conducting portion 4 toward one main surface 4 a side, and on the opposite main surface 4 b side. Partition walls 5A and 5B are formed. The partition walls 3A and 5A are formed on the outer edge of the separator over the entire circumference. Further, in addition to the partition walls 3A and 5A, the separator 1 is divided into the sections A by partition walls 3B and 5B that do not exist on the inner outer edge. On the first main surface side, each recess 2 is formed by the partition wall 3B, and on the second main surface side, each recess 6 is formed by the partition wall 5B. In this example, the planar shape of each recess is a square or a rectangle.

  As shown in FIG. 2A, the partition walls 3A and 5A, 3B and 5B are formed at positions overlapping each other in plan view. This means that when viewed in the thickness direction (direction E) of the separator, the partition walls 3A and 5A, 3B and 5B are in overlapping positions. Thereby, when pressure is applied to the separator 1 in the thickness E direction, the partition walls 3A and 5A, 3B and 5B support the pressure in the thickness direction. Can be maintained.

  Next, as shown in FIG. 2B, the first electrode 7 is formed in the first recess 2, and the second electrode 8 is formed in the second recess 6. Next, as shown in FIG. 2C, by forming the first current collector 9A on the first electrode 7 and forming the second current collector 9B on the second electrode 8, The secondary battery unit 10 is formed.

  FIG. 3A is a perspective view showing the secondary battery unit 11 thus obtained, and FIG. 3B shows one section thereof. FIG. 4A is a cross-sectional view of the unit of FIG.

  In the example of FIG. 4A, the partition walls 3A and 5A, 3B and 5B are formed at positions overlapping each other in plan view. This means that the partition walls 3 and 5 are in a position where they overlap when viewed in the thickness direction (direction E) of the separator. Thereby, when pressure is applied to the separator 1 in the thickness E direction, the partition walls 3A and 5A, 3B and 5B support the pressure in the thickness direction. Can be maintained.

  In the case of the separator 1A shown in FIG. 4B, the partition walls 3A and 5A, 3B and 5B are in a position overlapping each other when viewed in the thickness direction. However, in this example, the partition wall 12 is further formed on the second main surface side. As a result, the recess portion 6 is formed by the partition walls 5B and 12 on the second main surface side, and the electrode is formed in the recess portion 6. 8 is housed. In this example, since the partition walls 3A, 5A, 3B, and 5B overlap each other in the thickness direction, the structural strength of the separator can be maintained by these partition walls. Since the partition wall 12 does not have a partition wall corresponding to the first main surface side, the partition wall 12 does not work as a support for pressure.

  In this embodiment, at least a part of each of the recesses is partitioned by the partition wall of the present invention having a partition wall corresponding to the thickness direction, but a part thereof is a partition wall having no partition wall corresponding to the thickness direction (for example, It may be partitioned by a partition wall 12). Particularly preferably, the recess is defined by a partition wall having a partition wall corresponding to the thickness direction over the entire circumference.

  In the unit 16 shown in FIG. 4C, the partition walls 13A and 15A are located at positions overlapping each other when viewed in the thickness direction. However, the partition wall 13B on the first main surface side and the partition wall 15B on the second main surface side located inside from the outer edge portion are in positions where they do not overlap when viewed in the thickness direction of the separator. That is, the partition wall 13B does not have a partition wall corresponding to the second main surface side, and the partition wall 15B does not have a partition wall corresponding to the first main surface side.

  In the present invention, each recess is designed to be relatively shallow, so that each electrode can be easily accommodated in each recess. The movement of ions is a movement that passes through the ion conducting portion 4 between the electrodes 7 and 8, that is, a movement in the thickness direction of the separator. Electrons also move in the thickness direction of the separator in the same way as ion conduction. Therefore, by designing the electrode housing recesses to be relatively shallow, it is possible to design both the distance that the cations diffuse to the solid electrolyte separator and the distance that the electrons diffuse to the current collector. Thus, in addition to facilitating the battery manufacturing method, the battery can be designed with a small diffusion resistance inside the electrode layer.

  As for the arrangement of the electrode housing recesses, it is preferable to arrange the first electrode and the second electrode at the same position when viewed in the thickness direction. However, as shown in FIG. 4B, the shape of the electrode 7 and the shape of the electrode 8 do not need to match. However, if there is a partition wall 12 that does not have a corresponding partition wall on the opposite side, the electrode accommodation area decreases accordingly, and the utilization efficiency tends to decrease.

  The electrode housing recess has a structure in which a partition wall is provided around the electrode housing recess. By using this partition as a support and stacking, a series-connected assembled secondary battery is formed. When stacking, the battery unit is a high-potential assembled battery connected in series by blocking ion conduction between battery units and dividing (separating) with a current collector having electron conductivity. Also, a high-capacity assembled battery that is connected in parallel by pulling the current collecting unit to the side surface and alternately connecting it, or an assembled battery that interlaces in series and parallel are possible.

That is, although the secondary battery unit can be used alone, it is preferable to form an assembled battery (an assembled secondary battery) 20 by stacking as shown in FIGS. In this case, the current collecting portions 9A and 9B of the units 11 adjacent in the thickness direction come into contact with each other so that the adjacent units are connected in series. Electrons (current) flow in the thickness direction of the separator. And electric power is taken out from the upper end and lower end of the assembled secondary battery after being laminated.

  The electrode accommodated in the recess may contain an electrolytic solution. By adopting a structure in which the open surface of the recess is sandwiched by another unit via the current collector, it is possible to facilitate sealing (sealing) by the current collector and to prevent the electrolyte from leaking. A normal lithium ion secondary battery has a problem of liquid junction and cannot be connected in series in the battery. However, when this structure is used, it is possible to prevent liquid junction even when stacked.

  In a preferred embodiment, the width of the partition wall at the outermost periphery of the separator is relatively increased. The battery unit needs to be sealed (sealed) only at the outermost peripheral portion of the separator, and the liquid junction between the individual electrode housing portions does not pose a problem because of the parallel connection. For this reason, the internal seal (sealing) does not have to be made completely. However, since it is necessary to perform sealing (sealing) completely on the outermost periphery of the separator, it is desirable that the wall portion on the outermost periphery is provided with a sufficient width to ensure a bonding strength.

  A structure in which a certain volume is secured by a ceramic separator structure in which a partition wall is provided in the electrode housing recess is employed. Since the active material itself expands and contracts as the electrode active material is charged / discharged, if the charge / discharge state varies partially in the electrode layer, the electrode layer has a thickness variation. When the wall portion is not provided, a partial strain stress is applied to the ceramic separator due to the thickness variation, and the separator is cracked or cracked, leading to an internal short circuit of the battery and further destruction of the battery itself. However, if the electrode housing recess is configured in a space in which a certain volume is secured in advance, the electrode housing portion can maintain a constant shape regardless of the expansion and contraction of the electrode active material. For example, in a battery that uses a high-capacity active material that is expected to have a high energy density in the future, the number of lithium ions that enter and exit per unit active material weight (volume) increases, so inevitably the expansion of the active material itself It is known that shrinkage also increases. Typical examples include a sulfur positive electrode, an air battery positive electrode, and a battery to which a negative electrode made of lithium metal or a lithium alloy is applied as an example of an active material that is not expanded or contracted but has a large volume change. A battery using the separator of the present application in which an electrode housing portion is formed in advance is suitable for a battery using such an active material having a large expansion and contraction.

  In this embodiment, the separator has a waffle-like shape (a structure in which wall portions intersecting both surfaces of a thin plate are provided). By providing beams made of partition walls as necessary, it is possible to secure strength when the area is increased. Then, it is possible to obtain a structure in which a plurality of electrode housing portions are arranged in parallel in the plane direction in a matrix form. By connecting them in parallel via a current collector foil (sealed) layer, it becomes possible to obtain a battery pack having a high potential and a high capacity.

  A film of a metal that can be alloyed with an alkali metal used for the negative electrode can be formed on the inner surface of the concave portion on the negative electrode side, in addition to copper generally used for the negative electrode current collector. The metal film formed on the inner surface of the concave portion forms an anode active material by being alloyed with, for example, lithium metal during charging, and at the same time as an electron conduction path to the current collecting portion that seals (seals) the electrode housing portion. It has the function of.

  For the negative electrode current collector, a current collector layer having a current collector column protruding like a sword mountain can be used. The current collecting column extends from the current collecting portion toward the concave portion of the electrode housing portion, and is formed with a length reaching the bottom of the concave portion. In addition to the film part in which the negative electrode side electron conduction path is formed on the inner surface, the electron conduction can be secured via the current collecting column.

  In a preferred embodiment of the positive electrode portion, an electrode paste containing an electrode active material is applied and formed on the current collector foil so that the electrode is patterned in a portion corresponding to the concave portion of the electrode housing portion. An electrode layer impregnated with an electrolyte made of an organic electrolyte, a semi-solid gel, polymer, or the like is disposed and accommodated so that the electrode portion is accommodated in the recess of the electrode accommodating portion.

  That is, in the secondary battery unit 10A of FIGS. 7 and 8, a metal film 19 of copper or aluminum is formed on the inner surface of the recess 2 and is drawn out to the current collector 9A. A predetermined negative electrode 7 is deposited between the current collector 9A and the metal film 19. On the other hand, in the concave portion 6, the porous electrode layer 8 is formed by printing on the current collecting portion 9B, and the electrolytic solution is impregnated therein.

  In order to improve the energy density, the planar shape of each recess is designed freely as appropriate. In particular, from the viewpoint of close packing, a triangle, a rectangle, a square, a hexagon (honeycomb) shape, or a combination of a plurality of polygons is also preferable. On the other hand, from the viewpoint of structural strength, a shape such as a circle or an ellipse that does not have corners is preferable. In order to achieve both energy density and strength, a shape that is a combination of the characteristics of the two, a triangle, a quadrangle, a hexagon, and a plurality of polygons, with rounded corners is more preferable.

  For example, in the separator 21A of FIG. 9A, the planar shape of each recess 2A is a triangle. Moreover, in the separator 21B of FIG.9 (b), the planar shape of each recessed part 2B is a hexagon. Further, in the separator 21C of FIG. 9C, the planar shape of each recess 2C is circular.

The present invention can also be suitably applied to so-called air batteries.
In the air battery, the gas flow passage is formed by increasing the height of the first partition wall in one of the electrode housing recesses. In the air battery, there is a problem with the gas introduction method when the stacked stack is formed. However, when the separator having the above structure is used, stacking can be performed with the gas introduction port secured.

  As shown in FIG. 10, the separator 31 is formed with an elongated beam-shaped partition wall 35A on the outer edge of the separator on the first electrode side. In addition, a plurality of elongated beam-like partition walls 35B are arranged and formed inside the partition wall 35A. In addition, partition walls 33 lower than the partition walls 35A and 35B are formed between the partition walls 35A and 35B at regular intervals. Recesses 32 are formed by the partition walls 33 and 35A and 35B. A pair of opposing sides of each recess 32 is partitioned by a partition wall 35, and a pair of opposing sides is partitioned by a partition wall 33.

  On the other hand, on the other main surface 34b side of the electron conducting portion 34, an elongated beam-shaped partition wall 36A is formed on the outer edge of the separator. In addition, a plurality of elongated beam-like partition walls 36B are arranged and formed inside the partition wall 36A. Recesses 38 are formed by the partitions 36A and 36B. The height of the partition walls 36A and 36B is constant on the other main surface side. When viewed in the thickness direction of the separator, the partition walls 35 </ b> A and 36 </ b> A existing along the outer edge overlap each other. Further, when viewed in the thickness direction of the separator, the partition walls 33, 35B, and 36B are located at overlapping positions.

  As shown in FIG. 11, the electrode 33 is formed in the first recess 32, and the electrode 37 is formed in the second recess 38. A current collector 50 is formed on the electrode 37, and an oxygen permeable film 39 is formed on the electrode 33. A gas flow path 42 is formed on the oxygen permeable film 39 inside the partition walls 35A and 35B. The oxygen permeable film 39 transmits oxygen, suppresses the permeation of moisture and carbon dioxide, and suppresses the leakage of the electrolytic solution in the electrode housing portion.

The air battery units 40 thus obtained are stacked and stacked as shown in FIGS. That is, the current collector 50 and the partition walls 35 </ b> A and 35 </ b> B of the unit 41 adjacent in the stacking direction are brought into contact with each other and the gas flow path 42 is formed between the current collector 50 and the oxygen permeable film 39. Then, as shown in FIG. 12, the oxygen-containing gas flows into the gas flow path as indicated by arrow C and is discharged as indicated by arrow D. Even in this structure, the partition walls 35A, 35B and 36A, 36B are present at the same position in the stacking direction, and provide support columns extending in the stacking direction. Further, as in the above-described embodiment, both electrons and ions flow in the stacking direction.

  Preferably, as shown in FIGS. 15 and 16, oxygen permeable membranes 50 are provided on the gas inlet side and outlet side end faces of the assembled secondary battery. This oxygen permeable membrane permeates oxygen, suppresses permeation of moisture and carbon dioxide, and suppresses leakage of the electrolyte solution in the electrode housing portion. Reference numeral 45 denotes a current collector.

  FIG. 17 shows an example of the air battery unit 40A. A metal film 52 made of copper, aluminum, or the like is formed on the inner surface of the recess 38 by vapor deposition, sputtering, or the like. A negative electrode 37 </ b> A is accommodated in the recess 38, and the recess 38 is covered with the current collector 50. The negative electrode 37A is made of a negative electrode material such as lithium or a lithium alloy.

  On the other hand, an air electrode 60 is formed in the recess 32 on the opposite side. The air electrode 60 is obtained by embedding a current collecting member 51 in a catalyst layer 61 having mesopores, and the catalyst layer 61 is impregnated with an electrolytic solution.

  When battery units are stacked and stacked, the oxygen permeable membrane can be individually formed in each battery unit. However, from the viewpoint of improving energy density, it is preferable to collect the oxygen permeable membranes as shown in FIGS. After the batteries are stacked, the oxygen permeable membrane 50 is provided collectively.

As the positive electrode active material, various metal oxides, metal sulfides, and the like can be used. In particular, when a metal oxide is used, secondary battery sintering can be performed in an oxygen atmosphere. Specific examples of such a positive electrode active material include manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (eg, LixMn ₂ O ₄ or LixMnO ₂ ), lithium nickel composite oxide (eg, LixMnO ₂ ). _x NiO _2), lithium cobalt composite oxide _(Li x _CoO 2), lithium nickel cobalt composite oxide (e.g., _{LiNi 1-y Co y O 2} ), lithium manganese cobalt composite oxides (e.g. LiMn _y Co _1-y O _2), spinel type lithium-manganese-nickel composite oxide _{(Li x Mn 2-y Ni} y O 4), lithium phosphates having an olivine structure _{(Li x FePO 4, LixFe 1} -y Mn y PO 4, Li x CoPO _4, etc.), lithium phosphate compounds having a NASICON structure Li such _{x V 2 (PO 4) 3} ), include at least one selected from iron sulfate _{(Fe 2 (SO 4) 3} ), vanadium oxide (e.g. _V 2 _{O 5).} In these chemical formulas, x and y are preferably in the range of 0-1.
Further, it is possible to use sulfur or its compound as the positive electrode active material, S (sulfur), _Li 2 S (lithium sulfide), or _Li 2 _{S n} (lithium polysulphides) can be mentioned.

  In addition to the positive electrode active material, the positive electrode can appropriately include a conductive additive, a binder, a solid electrolyte described later, and the like. Examples of the conductive assistant include acetylene black, carbon black, graphite, various carbon fibers, and carbon nanotubes. Examples of the binder include polyvinylidene fluoride (PVDF), SBR, and polyimide.

Examples of the negative electrode active material include simple metal, carbon, metal compound, metal oxide, Li metal compound, Li metal oxide (including lithium-transition metal composite oxide), boron-added carbon, graphite, and NASICON structure. A compound having the above can be used. These may be used alone or in combination of two or more. Examples of the carbon include conventionally known carbon materials such as graphite carbon, hard carbon, and soft carbon. The single metal is Li, and the metal compound is LiAl, LiZn, Li ₃ Bi, Li ₃ Cd, Li ₃ Sd, Li ₄ Si, Li _4.4 Pb, Li _4.4 Sn, Li _0.17 C. (LiC _6), and the like. The metal _{oxides, SnO, SnO 2, GeO,} GeO 2, In 2 O, In 2 O 3, PbO, PbO 2, Pb 2 O 3, Pb 3 O 4, Ag 2 O, AgO, Ag 2 O ₃ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , SiO, ZnO, CoO, NiO, FeO and the like. Examples of the Li metal compound include Li ₃ FeN ₂ , Li _2.6 Co _0.4 N, Li _2.6 Cu _0.4 N, and the like. Examples of the Li metal oxide (lithium-transition metal composite oxide) include a lithium-titanium composite oxide represented by Li _x Ti _y O _z such as Li ₄ Ti ₅ O ₁₂ . Examples of the boron-added carbon include boron-added carbon and boron-added graphite. In addition to the positive electrode active material, the negative electrode can appropriately include a conductive additive, a binder, a solid electrolyte described later, and the like. The conductive aid and binder are the same as those already described in the section “Positive electrode active material and positive electrode”. Examples of the compound having a NASICON structure include lithium phosphate compounds (such as Li _x V ₂ (PO ₄ ) ₃ ).

For example, inorganic solid as the preferred electrolyte for use in electrolytic, _Li 3 PO ₄ including, _LiPO mixed with nitrogen _{Li 3 PO 4 4-x N} x (x is _{0 <x ≦ 1), Li} 2 S- Lithium ion conductive glassy solid electrolytes such as SiS ₂ , Li ₂ S—P ₂ S ₅ , Li ₂ S—B ₂ S ₃ , lithium halides such as LiI and lithium such as Li ₃ PO _{4 on} these glasses Examples thereof include a lithium ion conductive solid electrolyte doped with an oxyacid salt. Among them, a titanium oxide type solid electrolyte containing lithium, titanium, and oxygen, for example, Li _x La _y TiO ₃ (x is 0 <x <1, y is 0 <y <1) and NASICON type phosphoric acid compound For example, Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ (x is 0 <x <1) is preferable because it exhibits stable performance even in firing in an oxygen atmosphere.

A conventionally known polymer electrolyte can be used as the polymer solid electrolyte. For example, it is a layer composed of a polymer having ion conductivity, and the material is not limited as long as it exhibits ion conductivity. Examples of the all solid polymer electrolyte include known solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. The solid polymer electrolyte contains a lithium salt in order to ensure ionic conductivity. As the lithium salt, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or a mixture thereof can be used.

  Particularly preferably, the solid electrolyte separator contains Li, La, Zr, Nb and / or Ta, Al, and O, and the molar ratio of (Nb + Ta) / La is 0.03 or more and 0.20 or less, and Al / It consists of a garnet-type solid electrolyte material having a composition in which the molar ratio of La is 0.008 or more and 0.12 or less.

  The garnet-type solid electrolyte material having the above composition is a material having both high ionic conductivity and Li reduction resistance. Therefore, it is possible to achieve both the reduction of the resistance of the solid electrolyte portion and the suppression of the dendrite short circuit due to the negative electrode metal lithium, which is the most suitable material for the solid electrolyte ceramic separator proposed in the present application.

Conventionally known materials can be used for the positive electrode current collector and the negative electrode current collector. As the current collector material, a conductive metal oxide layer is preferably used. For _{example, SnO 2, In 2 O 3} , ZnO, TiO x (0.5 ≦ x ≦ 2) and the like. These conductive metal oxides may contain a trace element (for example, 10 at% or less) for enhancing conductivity such as Sb, Nb, Ta in the structure. In consideration of high temperature use and life, Cu and Al clad materials are preferable.

  The material constituting the external electrode is not particularly limited. For example, Ag, Ag / Pd alloy, Ni plating, Cu by vapor deposition, and the like can be mentioned. Further, solder plating for mounting may be performed on the surface of the external electrode. The connection form of the external electrode is not particularly limited.

As an air battery catalyst, oxides containing transition metals, carbon, Pt, or the like can be mainly used. Specific examples of the _{oxide, MnO 2, Mn 3 O 4} , FeO 2, Fe 3 O 4, NiO 2 and _{La 0.6 Sr 0.4 MnO 3, La} 0.6 Sr 0.4 FeO 3, LaNiO ₃ can be used. The fine structure of the catalyst is preferably a menoporous structure with a large specific surface.

As the electrolyte solution impregnated in the catalyst of the air battery, a solution obtained by dissolving an electrolyte such as a lithium salt in a nonaqueous solvent is used. A known nonaqueous solvent can be used as the nonaqueous solvent. For example, propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC) and the like can be mentioned, and a mixed solvent thereof is preferable. Examples of the electrolyte contained in the non-aqueous electrolyte include lithium perchlorate (LiClO _4).
), Lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), and the like. A gel electrolyte can also be used. Specifically, a nonaqueous electrolytic solution composed of a polymer material and a nonaqueous electrolytic solution can be used. Examples of the polymer material include polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), and the like.

Claims (8)

A secondary battery unit comprising a solid electrolyte separator ,
The separator is formed of a dense solid electrolyte having ion conductivity for a secondary battery, the first electrode and the second electrode of the secondary battery are divided, and the separator is a plate-like ion conductive portion, A first partition wall protruding from the ion conductive portion toward the first main surface side, a second partition wall protruding from the ion conductive portion toward the second main surface side, and opening to the first main surface side; A first recess for accommodating the first electrode, and a second recess for opening the second electrode and opening the second main surface, and including a periphery of the first recess. At least a portion is divided by the first partition, at least a portion of the periphery of the second recess is partitioned by the second partition, and the first electrode is a negative electrode,
The secondary battery unit is
A first current collector that covers the first recess, blocks ion conduction, and has electron conductivity;
A second current collector that covers the second recess, blocks ionic conduction, and has electronic conductivity; and
A secondary battery unit , comprising a metal film provided on an inner surface of the first recess, wherein the metal film functions as an electron conduction path to the first current collector . The secondary battery unit according to claim 1, wherein a planar shape of the first recess and the second recess is a polygon or a circle. The secondary battery unit according to claim 1, wherein the ion is lithium. The secondary battery unit according to claim 3, wherein the first electrode includes at least one of lithium metal and a lithium alloy. The solid electrolyte separator contains Li, La, Zr, Nb and / or Ta, Al, and O, and a molar ratio of (Nb + Ta) / La is 0.03 or more and 0.20 or less, and a mole of Al / La The secondary battery unit according to any one of claims 1 to 4, wherein the secondary battery unit is made of a garnet-type solid electrolyte material having a composition with a ratio of 0.008 to 0.12. An assembled secondary battery, wherein a plurality of the secondary battery units according to any one of claims 1 to 5 are stacked. An air battery unit comprising a solid electrolyte separator,
The separator is formed of a dense solid electrolyte having ion conductivity for a secondary battery, the first electrode and the second electrode of the secondary battery are divided, and the separator is a plate-like ion conductive portion, A first partition wall protruding from the ion conductive portion toward the first main surface side, a second partition wall protruding from the ion conductive portion toward the second main surface side, and opening to the first main surface side; A first recess for accommodating the first electrode, and a second recess for opening the second electrode and opening the second main surface, and including a periphery of the first recess. At least a portion is divided by the first partition, at least a portion of the periphery of the second recess is partitioned by the second partition, and the first electrode is a negative electrode,
The air battery unit is
A current collector that covers the first recess, blocks ion conduction, and has electron conductivity;
An oxygen permeable membrane covering the second recess, and
An air battery unit comprising a metal film provided on an inner surface of the first recess, wherein the metal film functions as an electron conduction path to the current collector . An assembled secondary battery, wherein a plurality of the air battery units according to claim 7 are stacked.

Images