JP2012204160A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery which does not need an air-tight exterior package, is directly surface-mounted to a circuit board, and is not likely to be damaged when used even though the thickness of a power generation element is reduced.SOLUTION: A secondary battery includes: a lamination type power generation element formed by laminating a first electrode made of an oxide sintered body, a solid electrolyte layer, and a second electrode made of an oxide sintered body in this order; and an insulative substrate at which a pair of terminal electrodes are provided. The first electrode and the second electrode respectively and electrically connect with the pair of terminal electrodes of the insulative substrate through a first collector and a second collector. Further, at least one of the first electrode and the second electrode is joined to the insulative substrate.

Description

  The present invention relates to a secondary battery using a solid electrolyte.

  In recent years, secondary batteries have been used not only for mobile phones and notebook PCs but also as batteries for electric vehicles.

  Conventionally, as an electrolyte of a secondary battery, an electrolyte obtained by impregnating a porous membrane called a separator with a non-aqueous electrolyte solution has been used. Secondary batteries using solid electrolytes have been proposed from the viewpoint of simplifying the liquid injection process and the like and simplifying the battery structure.

  A secondary battery using a solid electrolyte can avoid the above-mentioned problems such as leakage because the electrolyte is not liquid, and can be directly mounted on a circuit board. As such a secondary battery, a simple structure that does not require an airtight exterior body made of a metal case, a laminate sheet, a resin, or the like, for example, a plurality of layers in which a positive electrode and a negative electrode are bonded via a solid electrolyte. There has been proposed an all-solid-state secondary battery in which a pair of external current collectors respectively connected to either a positive electrode or a negative electrode are attached to both side surfaces of a rectangular parallelepiped laminate that is a power generation element (Patent Document) 1).

JP 2007-80812 A

  However, in the all-solid-state secondary battery described in Patent Document 1, when the electrode or solid electrolyte is thinned or the number of stacked power generation elements is reduced in order to satisfy the low profile requirement required for the battery, There was a problem that the laminate was damaged when the surface was mounted on a circuit board due to insufficient strength of the laminate.

  An object of the present invention is to provide a secondary battery that can be directly surface-mounted on a circuit board without requiring an airtight exterior body, and is not easily damaged even when the power generation element is thin. .

  The secondary battery of the present invention includes a laminated power generation element in which a first electrode made of an oxide sintered body, a solid electrolyte layer, and a second electrode made of an oxide sintered body are laminated in this order; An insulating substrate provided with a pair of terminal electrodes, wherein the first electrode and the second electrode are connected to the pair of insulating substrates by the first current collector and the second current collector. Each of the electrodes is electrically connected to a terminal electrode, and at least one of the first electrode and the second electrode is bonded to the insulating substrate.

  ADVANTAGE OF THE INVENTION According to this invention, even if it makes thickness of an electric power generation element thin, it is hard to be damaged at the time of handling, and can provide the secondary battery which can be surface-mounted directly to a circuit board.

It is a perspective view which shows the secondary battery which is one Embodiment of this invention. It is a figure which shows the AA line longitudinal cross-section of the secondary battery of FIG. It is a longitudinal cross-sectional view which shows the secondary battery which is another embodiment of this invention. It is a top view of the secondary battery of FIG. It is a longitudinal cross-sectional view which shows the state which provided the protective layer in the secondary battery of FIG.

  FIG. 1 is a perspective view showing a secondary battery according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view taken along line AA.

  The secondary battery of this embodiment includes a negative electrode 1 that is a first electrode made of an oxide sintered body, a solid electrolyte layer 3, and a positive electrode 2 that is a second electrode made of an oxide sintered body. The surface of the negative electrode 1 of the stacked power generation element 9 that is sequentially stacked is disposed on the insulating substrate 4 provided with the positive electrode terminal 5P and the negative electrode terminal 5N that are a pair of terminal electrodes, and the negative electrode current collector that is the first current collector. It is joined by the body 7. In this case, the negative electrode current collector 7 is responsible for fixing the laminated power generation element 9 and the insulating substrate 4 in addition to the electrical connection between the negative electrode 1 and the negative electrode terminal 5N. The positive electrode 2 and the positive electrode terminal 5P are electrically connected by a positive electrode current collector 8 that is a second current collector.

  Here, an insulating adhesive 10 may be used for joining the laminated power generation element 9 and the insulating substrate 4 as shown in FIG. 3, and in this case, the positive electrode terminal 5P and the negative electrode terminal 5N are connected to the negative electrode current collector. Short-circuiting by the body 7 can be effectively prevented. The insulating adhesive 10 may not be in contact with the negative electrode current collector 7 and may partially cover the negative electrode terminal 5N as long as electrical connection between the negative electrode 1 and the negative electrode terminal 5N is not hindered. On the other hand, in terms of simplification of the process and simplification of the constituent material, the negative electrode current collector 7 that electrically connects the negative electrode 1 and the negative electrode terminal 5N is interposed between the laminated power generation element 9 and the insulating substrate 4. It is preferable that the laminated power generation element 9 and the insulating substrate 4 are joined by being provided so as to be positioned. In this case, it is desirable that the positive electrode current collector 8 be provided separately from the negative electrode 1 and the solid electrolyte layer 3 located on the side surface of the multilayer power generation element 9.

  In the present embodiment, the insulating material 6 is provided between the negative electrode 1 and the solid electrolyte layer 3 located on the side surface of the multilayer power generation element 9 on the positive electrode terminal 5P side and the positive electrode current collector 8 provided there. It is preferable. If the conductive positive electrode current collector 8 is directly formed on the side surface of the multilayer power generation element 9, the positive electrode 2 is short-circuited to the negative electrode 1 through the positive electrode current collector 8, and the function as a battery is lost. By covering the side surface on the positive electrode terminal 5P side of the multilayer power generation element 9 with the insulating material 6 in advance, a short circuit due to the positive electrode current collector 8 can be prevented. The width of the insulating material 6 formed on the side surface of the multilayer power generation element 9 is made larger than the width of the positive electrode current collector 8 (see FIGS. 1 and 4). It can prevent more reliably that the positive electrode collector 8 contacts the exposed negative electrode 1. FIG.

  The secondary battery according to the present embodiment functions as a battery in this state. However, in order to improve moisture resistance, to prevent a short circuit due to contact with a foreign material, and to prevent damage in advance, as shown in FIG. It is preferable to cover the power generation element 9, the negative electrode current collector 7, and the positive electrode current collector 8 with an insulating protective film 11. The protective film 11 can be formed of an epoxy resin or low-melting glass, but an epoxy resin is preferable from the viewpoint of moisture permeability, strength, workability, and the like.

The thickness of the insulating substrate 4 used for the secondary battery of this embodiment is 0.1 to 0.3 mm, and it is preferable to use resin or ceramics as the material. The type of resin or ceramic used for the insulating substrate 4 is not particularly limited, and a resin such as phenol, epoxy, (Teflon (registered trademark)), or any of these resins and paper or glass is combined. And ceramics such as alumina, glass ceramics in which ceramics and glass are combined, and the like can be used. In particular, it is preferable to use alumina from the viewpoint of having high strength as a support and high insulating properties even with the above thickness.

  The insulating substrate 4 is provided with a positive terminal 5P and a negative terminal 5N made of gold or copper. In this embodiment, the insulating substrate 4 is provided with a pair of through holes, the conductive portions on both sides of the insulating substrate 4 formed around the through holes are connected via the respective through holes, and the positive terminal 5P and The negative terminal 5N is used.

  Further, the first current collector is responsible for joining the multilayer power generation element 9 and the insulating substrate 4 and electrically connects the negative electrode 1 of the multilayer power generation element 9 and the negative electrode terminal 5N of the insulating substrate 4. As the negative electrode current collector 7, a conductive adhesive containing a carbon material, a metal material (aluminum, gold, platinum, etc.) or a conductive oxide material (indium tin oxide (ITO) glass, tin oxide, etc.) as a filler is used. It is preferable to use it. By applying these conductive adhesives to desired portions of the insulating substrate 4 and bringing the surface of the laminated power generation element 9 on the negative electrode 1 side into contact therewith, the conductive adhesive is dried or cured. The negative electrode current collector 7 can be obtained. The positive electrode current collector 8, which is a second current collector that does not need to bear the bonding between the laminated power generation element 9 and the insulating substrate 4, may use the conductive adhesive as described above. In addition, a conductive paint including a carbon material, a metal material (aluminum, gold, platinum, or the like) or a conductive oxide material (indium tin oxide (ITO) glass, tin oxide, or the like) as a filler can also be used.

  As the electrode used in the secondary battery of the present embodiment, a dense oxide sintered body is used for both the negative electrode 1 and the positive electrode 2. The dense oxide sintered body is a sintered body substantially consisting of an oxide-based active material and having a porosity of 15% or less. By making the electrode a dense body of only the active material, not only can the capacity decrease due to conductive aids, binders, solid electrolytes, etc. not directly related to power generation be suppressed, but the joint area between the active materials can be greatly increased, The original electronic conductivity and ionic conductivity of the oxide-based active material can be effectively utilized, and a secondary battery having high capacity, high energy density and excellent output characteristics can be obtained. Moreover, moisture resistance can be improved by reducing the surface area of the electrode in contact with the atmosphere.

  Furthermore, the junction area with the solid electrolyte layer 3 which opposes can be enlarged by making the negative electrode 1 and the positive electrode 2 into a dense sintered compact. That is, in an electrode having many defects such as voids, a bonding interface with the solid electrolyte layer 3 is not formed in the defective portion. As a result, the number of ion paths decreases, the internal resistance increases, and the battery performance decreases. Ideally, the porosity of the oxide sintered body is desirably 0%, but the acceptable porosity is preferably 15% or less, and more preferably 10% or less.

The active material used for the electrode is not particularly limited as long as a dense oxide sintered body can be formed. Examples of the active material used for the oxide sintered body forming the positive electrode 2 include lithium cobalt composite oxide, Examples thereof include lithium manganese composite oxide, manganese dioxide, lithium nickel composite oxide, lithium nickel cobalt composite oxide, lithium nickel manganese composite oxide, lithium vanadium composite oxide, and vanadium oxide. In particular, lithium nickel manganese composite oxide (LiNi _x Mn _y O ₄ (x = 0.1 to 0.5, y = 1.5 to 1.9)) has a high charge / discharge voltage and a large charge / discharge capacity. It is an active material particularly suitable for increasing the capacity and energy density of secondary batteries. On the other hand, lithium cobalt composite oxide is excellent from the viewpoint of electron conductivity, and lithium cobalt composite oxide can also be suitably used in applications that require rapid charge / discharge.

Examples of the active material used for the oxide sintered body forming the negative electrode 1 include titanium oxide, tungsten oxide, molybdenum oxide, niobium oxide, vanadium oxide, iron oxide, and the like, and lithium composite oxide composed of these oxides and lithium. Can be used. In particular, it is preferable to use lithium titanium composite oxide (Li ₂ Ti ₃ O ₇ and its related active materials) which is lithium titanate. Since lithium titanate has a low charge / discharge potential and a large charge / discharge capacity among oxides, a secondary battery having a high voltage can be formed when used as an active material of the negative electrode 1.

  The solid electrolyte layer 3 is required to pass ions and prevent a short circuit between the positive and negative electrodes. Therefore, the thickness of the solid electrolyte layer 3 is preferably as thin as possible in order to shorten the moving distance as a path for ions, and specifically, the total thickness of the solid electrolyte layer 3 is preferably 10 μm or less. Is 3 μm or less, more preferably 1 μm or less. When the thickness of the solid electrolyte layer 3 is thin, the internal resistance due to the solid electrolyte is reduced, and battery performance such as output characteristics is improved. Further, if the thickness of the solid electrolyte layer 3 can be reduced, more active material can be packed as compared with the secondary battery having the same volume, so that the capacity is increased and as a result, the energy density is also improved. However, in order to prevent a short circuit, it is necessary to ensure a minimum thickness that does not cause a breakdown due to dielectric breakdown or pinholes.

  The solid electrolyte layer 3 is formed by joining, for example, a first solid electrolyte on the negative electrode side provided on the negative electrode 1 and a second solid electrolyte on the positive electrode side provided on the positive electrode 2.

  As a method for forming the first solid electrolyte and the second solid electrolyte on the surfaces of the negative electrode 1 and the positive electrode 2 made of an oxide sintered body, respectively, a liquid phase synthesis method or a gas phase synthesis method can be used. The synthesis method is suitable because a thin, uniform and dense film can be easily formed and the interface resistance can be reduced.

The solid electrolyte used in the present embodiment includes lithium, which is considered to be capable of following the change in the shape of the interface accompanying the change in the volume of the electrode and suppressing the increase in the interface resistance due to the presence of random ion conduction paths. preferably the glass-based solid electrolytes such as _{Li 1 + x Zr 2 Si x} P 3-x O 12, Li 1 + x Zr 2-x / 3 Si x P 3-x O 12-2x / 3 (1.5 <x <2. 2), Li _{1 + x} M _x Ti _2-x (PO ₄ ) ₃ (M = Al, Sc, Y, or La, 0 <x <2), Li _0.5-3x M _{0.5 + x} TiO ₃ (M = La, Pr, Nd, or Sm, 0 <x <1/6), Li ₂ SO ₄ , Li ₄ SiO ₄ , Li ₃ PO ₄ , Li ₄ GeO ₄ , Li ₃ VO ₄ , Li ₂ MoO ₄ , Li ₄ ZrO _4, Li _{2 O 3, Li 2 O, LiPON} , SiO 2, ZrO 2, V 2 O 5, P 2 O 5, B 2 O 3, Al 2 O 3, TiO 2, Zn 2 GeO 4, Li 2 S, SiS 2, _{li 2 Se, SiSe 2, B} 2 S 3, P 2 S 5, GeS 2, LiI, LiW 2 O 7, LiNbO 3 and the like. Among them, lithium phosphate oxynitride (hereinafter also referred to as LIPON) has a high ionic conductivity of about 1 × 10 ⁻⁶ S / cm at room temperature and is known to be electrochemically stable over a wide potential range. It is suitable.

  A method for manufacturing the secondary battery of this embodiment will be described.

  First, sintered bodies to be the negative electrode 1 and the positive electrode 2 are produced. For example, lithium titanium composite oxide is used as the active material for the negative electrode 1, and lithium manganese composite oxide is used as the active material for the positive electrode 2, and these active materials and binders such as butyral are optionally added with a dispersant and a plasticizer. The added water or an organic solvent such as toluene is mixed as a solvent by a well-known method to prepare negative electrode and positive electrode slurries. The slurry is coated on a base film such as a polyethylene terephthalate (PET) film by a known method and dried to produce a green sheet having a desired thickness. At this time, the slurry may be dried and granulated, and a green sheet may be produced by roll pressing, or may be press-formed into a desired shape.

The obtained green sheet is punched into a desired shape, degreased as necessary, and then fired to obtain a dense sintered body that becomes the negative electrode 1 and the positive electrode 2. What is necessary is just to select a calcination temperature suitably according to the sinterability of the active material which is raw material powder.

Next, for example, LIPON is formed as a first solid electrolyte and a second solid electrolyte on the surfaces of the obtained negative electrode 1 and positive electrode 2 by a gas phase synthesis method, respectively. LIPON is a lithium phosphate (Li ₃ PO ₄ ) in which part of the oxygen is replaced with nitrogen, and the film is formed by reactive high-frequency sputtering using lithium phosphate as a target in a nitrogen atmosphere. Can do.

  Thereafter, the negative electrode 1 and the positive electrode 2 are laminated so that the first solid electrolyte and the second solid electrolyte are opposed to each other, and the solid electrolytes are joined together to produce the laminated power generating element 9. LIPON is stable even when heated in a non-oxidizing atmosphere, particularly in a nitrogen atmosphere, and the ionic conductivity does not change. For example, LIPON is hot-pressed at a temperature of 500 ° C. to 800 ° C. in a nitrogen atmosphere, for example. By joining the first solid electrolyte and the second solid electrolyte on the positive electrode 2 side, the solid electrolytes 9 can be produced by joining the solid electrolytes while suppressing the deterioration of LIPON.

  As described above, the first solid electrolyte and the second solid electrolyte are respectively formed on the surfaces of the negative electrode 1 and the positive electrode 2 made of a dense oxide sintered body by a vapor phase synthesis method, and the solid electrolytes are directly bonded to each other. Thus, it is possible to obtain the stacked power generation element 9 having a high capacity and a high energy density. The thickness of the laminated power generation element 9 created in this way can be set to 0.1 to 0.3 mm, for example.

  Next, the insulating material 6 is apply | coated to the side surface of the side connected with the positive electrode terminal 5P of the obtained laminated | stacked electric power generation element 9. FIG. The insulating material 6 is for preventing the negative electrode 1 and the positive electrode 2 from being short-circuited by the positive electrode current collector 8 and may be any material having an insulating property, and the material is not particularly limited. For example, an epoxy resin, a phenol resin, a urethane resin, or the like can be used. As a coating method, a known coating method may be selected as necessary, such as a dip coating method or a printing method. If insulation between the positive electrode current collector 8 and the negative electrode 1 can be ensured, an insulating plate such as resin or ceramics is provided on the side of the laminated power generation element 9 that is connected to the positive electrode terminal 5P, or an insulating film is coated. May be. The insulating material 6 formed on the side surface of the multilayer power generation element 9 is placed on the surface side of the negative electrode 1 so that the surface bonded to the insulating substrate 4 of the negative electrode 1 does not contact the positive electrode terminal 5P of the insulating substrate 4. You may wrap around. The insulating material 6 may wrap around the other side surface adjacent to the side surface on the side connected to the positive electrode terminal 5P or the surface side of the positive electrode 2.

  Next, the laminated power generation element 9 and the insulating substrate 4 including the positive electrode terminal 5P and the negative electrode terminal 5N are joined. A region where the laminated power generating element 9 is bonded is defined on the main surface of the insulating substrate 4, and a conductive adhesive using, for example, carbon as a filler is applied to the region by a known printing method or the like. The region where the conductive adhesive is applied includes the negative electrode terminal 5N, and the multilayer power generation element 9 is connected to the region so that the negative electrode 1 and the negative electrode terminal 5N of the multilayer power generation element 9 are electrically connected to each other. Install and join. The conductive adhesive solidified between the stacked power generation element 9 and the insulating substrate 4 serves as an electrical connection between the negative electrode 1 and the negative electrode terminal 5N as the negative electrode current collector 7. In order to prevent the conductive adhesive from being directly formed on the positive electrode terminal 5P, the positive electrode terminal 5P on the main surface of the insulating substrate 4 and its peripheral portion may be masked before applying the conductive adhesive. Good. This masking may be removed after the conductive adhesive is applied, or may not be removed if the electrical connection between the positive electrode terminal 5P and the positive electrode current collector 8 is not hindered.

  The positive electrode current collector 8 that electrically connects the positive electrode 2 and the positive electrode terminal 5P includes a side surface on which the insulating material 6 is formed from the surface of the positive electrode 2 of the stacked power generation element 9 and a positive electrode terminal on the main surface of the insulating substrate 4. Over 5P, for example, a conductive paint using carbon as a filler can be applied and dried to form the secondary battery of this embodiment.

  Furthermore, if necessary, as shown in FIG. 5, the laminated power generation element 9 side of the obtained secondary battery is covered with an epoxy resin to form a protective film 11. The protective film 11 only needs to cover at least the multilayer power generation element 9, the negative electrode current collector 7, and the positive electrode current collector 8, and the mounting portions of the positive electrode terminal 5P and the negative electrode terminal 5N are exposed to the circuit board or the like. May be formed on the entire surface of the secondary battery.

  As described above, the secondary battery according to one embodiment of the present invention has been described. However, the present invention is not limited to this embodiment, and of course a combination in which the first electrode is a positive electrode and the second electrode is a negative electrode. The present invention can be applied to various modifications without departing from the scope of the present invention.

(1) and a butyral is Li _0.5 Mn _1.5 O ₄ and a binder is a manufacturing process the cathode active material of the positive electrode material, toluene and mixed in a ball mill as a solvent, to prepare a slurry for positive electrode. And the slurry for positive electrodes was apply | coated on the polyerylene terephthalate film, and it was made to dry, and the green sheet for positive electrodes with a thickness of 125 micrometers was produced. Thereafter, a green sheet for a positive electrode is punched into a size of 7 mm × 18 mm, fired at 1000 ° C., and then heat-treated at 700 ° C. for 10 hours, whereby a dense Li having a thickness of 100 μm, a size of 6 mm × 15 mm, and a porosity of 10%. A positive electrode of an oxide sintered body made of _0.5 Mn _1.5 O ₄ was produced.

(2) Production process of negative electrode material Li ₂ Ti ₃ O _{7 as} a negative electrode active material and butyral as a binder were mixed by a ball mill using toluene as a solvent to prepare a negative electrode slurry. And the slurry for negative electrodes was apply | coated on the polyerylene terephthalate film, and it was made to dry, and the green sheet for negative electrodes with a thickness of 125 micrometers was produced. Thereafter, a green sheet for a negative electrode is punched into a size of 7 mm × 18 mm and baked at 1100 ° C., whereby an oxide made of dense Li ₂ Ti ₃ O ₇ having a thickness of 100 μm, a size of 6 mm × 15 mm, and a porosity of 10%. A sintered negative electrode was prepared.

(3) Solid electrolyte formation process on each electrode The positive electrode and the negative electrode are each mounted on a sample holder of a high-frequency magnetron sputtering apparatus, a lithium phosphate sintered compact target is loaded, and a nitrogen atmosphere (pressure: 5 mtorr) is formed for 5 hours. A membrane was formed, and a solid electrolyte having a thickness of 0.5 μm was formed on the surfaces of the positive electrode and the negative electrode, respectively.

(4) Solid electrolyte bonding step The positive electrode solid electrolyte prepared in step (3) and the negative electrode solid electrolyte are set in the press portion in the hot press apparatus so that they face each other, and after both are brought into contact with each other, the atmosphere The gas was replaced from nitrogen to nitrogen. The atmosphere after the substitution was set to 0.1 MPa nitrogen. In that state, the temperature was raised to 600 ° C. over 1 hour, and when the temperature reached 800 ° C., a pressure of 10 MPa was applied between the electrodes by a press device, and the solid electrolytes were heated and joined. Then, it cooled to near room temperature and produced the laminated type electric power generation element.

(5) Formation of insulating material Among the side surfaces of the multilayer power generation element produced in step (4), a surface on which a positive electrode current collector is formed is determined, and a container containing a two-component epoxy resin in which the surface is mixed in advance And the side part was covered with an epoxy resin, and then allowed to stand until the epoxy resin was cured.

(6) Adhesion step between the laminated power generation element and the insulating substrate An insulating substrate made of alumina ceramics having a positive electrode terminal and a negative electrode terminal formed in advance is prepared, and the positive electrode terminal is attached to the portion where the laminated power generation element is bonded. In order to avoid contact, a conductive adhesive containing carbon as a filler is supplied by a dispenser, and the laminated power generation element is pressed therewith the negative electrode facing down, and the laminated power generation element is fixed after waiting for the adhesive to harden. . The conductive adhesive used here becomes a negative electrode current collector that bonds and fixes the multilayer power generation element to the insulating substrate and electrically connects the negative electrode of the multilayer power generation element and the negative electrode terminal of the insulating substrate.

(7) Formation process of positive electrode current collector In order to electrically connect the positive electrode and the positive electrode terminal, carbon is used as a filler by using a dispenser from the positive electrode of the stacked power generation element to the side surface portion where the insulating material is formed and the positive electrode terminal. A conductive paint was applied. After coating, the positive electrode current collector was formed by heating at 60 ° C. for about 5 minutes.

(8) Evaluation test of secondary battery In order to confirm the strength in handling the secondary battery obtained by the steps (1) to (7), a mounting test on a test printed circuit board is performed by a surface mounter. It was. As a result, the secondary battery was not damaged in the mounting test using the surface mounting machine.

In addition, a charge / discharge test was performed under the following conditions to confirm battery performance.
Charge / discharge voltage range: upper limit 3.7V, lower limit 1.5V
Charge / discharge current value: 10 μA (constant current charge / discharge)
Measurement temperature: 30 ° C
As a result of the charge / discharge test, it was confirmed that charge / discharge can be repeated at an average discharge voltage of 3.0V.

(9) Formation of protective film In order to further increase the moisture resistance and mechanical strength of the secondary battery produced by the steps (1) to (7), the entire laminated power generation element side of the secondary battery is made of epoxy resin. Covered to form a protective film. In this example, the insulating battery surface of the secondary battery is sucked and fixed with suction tweezers, and the laminated power generation element side of the secondary battery is immersed in a container containing the epoxy resin to protect the epoxy resin. Film formation was performed.

(10) Confirmation of effect of protective film A secondary battery provided with a protective film and a secondary battery without a protective film are left in a high-temperature and high-humidity tank at 85 ° C. and 95% RH for 100 hours, and both are charged and discharged. A test was conducted.

  As a result of the charge / discharge test, the discharge capacity of the secondary battery without the protective film was reduced by about 12% compared to the capacity obtained in the step (8). On the other hand, in the secondary battery provided with the protective film, the capacity decrease was only 4%. Moreover, the strength of the secondary battery was further improved by forming the protective film with an epoxy resin.

DESCRIPTION OF SYMBOLS 1 ... Negative electrode 2 ... Positive electrode 3 ... Solid electrolyte 4 ... Insulating board | substrate 5N ... Negative electrode terminal 5P ... Positive electrode terminal 6 ... Insulating material 7 ... Negative electrode collector 8 ...・ Positive electrode current collector 9... Laminated power generation element 10 ..insulating adhesive 11 ..protective film

Claims (9)

  A laminated power generation element in which a first electrode made of an oxide sintered body, a solid electrolyte layer, and a second electrode made of an oxide sintered body are laminated in this order, and a pair of terminal electrodes are provided An insulating substrate, and the first electrode and the second electrode are electrically connected to the pair of terminal electrodes of the insulating substrate by a first current collector and a second current collector, respectively. The secondary battery is characterized in that at least one of the first electrode and the second electrode is bonded to the insulating substrate.   The first current collector is provided so as to be positioned between the stacked power generation element and the insulating substrate, and the second current collector is formed of the first electrode and the solid electrolyte layer. The secondary battery according to claim 1, wherein the secondary battery is provided apart.   The secondary battery according to claim 2, wherein an insulating material is provided between the first electrode and the solid electrolyte layer, and the second current collector.   The laminated power generation element, the first current collector, and the second current collector are covered with an insulating protective film, according to any one of claims 1 to 3. Secondary battery.   The secondary battery according to claim 4, wherein the insulating protective film is made of an epoxy resin.   The secondary battery according to claim 1, wherein the first current collector is made of a conductive adhesive.   The active material of the oxide sintered body forming either one of the first electrode and the second electrode is a lithium nickel manganese composite oxide. A secondary battery according to any one of the above.   8. The active material of the oxide sintered body forming one of the first electrode and the second electrode is a lithium titanium composite oxide. 9. Secondary battery described in 1.   The secondary battery according to claim 1, wherein the solid electrolyte layer is made of lithium phosphate oxynitride.

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