JP6264189B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device.

In recent years, the use of lithium secondary batteries as a power source for mobile electronic devices such as mobile communication devices such as mobile phones and smartphones, game machines, and portable music players has spread.
In addition, wearability of electronic devices such as weight reduction, miniaturization, and fashionability of electronic devices is progressing, and the need for flexibility is increasing in order to obtain a degree of freedom in external design.

  In order to drive these electronic devices for a long time, research and development of a long life and high capacity of a lithium ion secondary battery have been actively conducted.

  Conventionally, a non-aqueous lithium ion secondary battery has a positive electrode and a negative electrode coated with a positive electrode active material or a negative electrode active material that absorbs and releases lithium ions on both sides of a sheet-like current collector such as aluminum or copper, A separator is sandwiched between the positive electrode and the negative electrode to be wound a plurality of times to form a wound body, which is sealed with an electrolyte in a cylindrical, square, or coin-shaped exterior body.

However, each member of the positive electrode, the negative electrode, and the separator has flexibility, but the flexibility is lost because the shape is fixed because it is formed by applying tension during winding and sealed in various exterior bodies. It will be broken. For this reason, the degree of freedom in external design cannot be obtained, and it has been difficult to provide a lithium ion secondary battery in a bent portion of an electronic device.
In addition, such a lithium ion secondary battery uses a liquid containing a flammable organic solvent in the electrolyte, which may cause liquid leakage due to an unexpected impact or the like, which is not preferable. Therefore, improvement in reliability has been desired.

Therefore, research and development of all-solid secondary batteries that do not use conventional non-aqueous electrolytes are actively conducted.
The all-solid-state secondary battery has a current collector, a positive electrode active material, a solid electrolyte, a negative electrode active material, and a current collector, and is flexible by making the whole battery thin or mounting it on a flexible substrate in the form of a chip. Can be realized (Patent Document 1).
Moreover, as described in Patent Document 2, by replacing the conventional non-aqueous electrolyte with an organic solid electrolyte or an inorganic solid electrolyte, there is no risk of liquid leakage, and a highly reliable lithium ion secondary battery is obtained. Can be realized.

JP2013-239435A Japanese Patent No. 5165443

  However, when a power storage device in which a plurality of power storage elements disclosed in Patent Document 1 is mounted on a flexible substrate is mounted and used on various wearable products such as bracelets or watches, the power storage device Is curved and used. When such a power storage device is bent, the power storage element may be damaged or the power storage element may be dropped. In addition, when a power storage device is mounted on a flexible substrate at a high density in order to increase the capacity and voltage of the power storage device, the power storage device may drop from the flexible substrate or a disconnection failure may occur. there were. When a disconnection failure occurs, there is a possibility that the capacity and voltage of the power storage device are rapidly reduced and the operation becomes impossible.

  Accordingly, an object of the present invention is to provide a power storage device in which a solid battery having excellent reliability is mounted on a flexible substrate, preventing the solid battery mounted at a high density from falling off, and reducing the disconnection failure. An object is to provide a power storage device having high flexibility.

  A power storage device according to the present invention includes a first solid battery group configured by electrically connecting a plurality of first solid batteries on a main surface of a flexible substrate in which wiring is provided on a resin substrate, A second solid state battery group configured by electrically connecting a plurality of second solid state batteries is mounted on the back surface opposite to the main surface of the flexible substrate, and the first solid state battery and the second solid state battery are mounted. The battery is characterized in that a cross section when cut in a direction perpendicular to the main surface is a trapezoid, and a long base side of the side of the trapezoid is the substrate side.

  According to such a configuration, when the first solid state battery or the second solid state battery having the trapezoidal cross section is mounted on the flexible substrate in which the wiring is applied to the resin substrate, the land and the second layer formed on the flexible substrate are arranged. Since the slope of the joint formed between the terminal electrode of the first solid battery or the second solid battery becomes gentle, local stress concentration on the joint is avoided when the flexible substrate is bent. Therefore, it is possible to obtain a power storage device in which cracks in the joint portion are reduced and solid battery dropping and disconnection failure are thereby suppressed.

  The power storage device according to the present invention is characterized in that, when projected from the back surface side, an overlapping area of the first solid state battery and the second solid state battery is half or less of a mounting area of the first solid state battery group. To do.

  According to this configuration, the tensile stress caused by the bonding agent generated on the main surface of the flexible substrate and the back surface opposite to the main surface overlaps the first solid battery and the second solid battery. This cancels out in the region, and the cracks at the joint are further reduced, thereby preventing the solid battery from falling off or being disconnected.

  The power storage device according to the present invention has a plurality of first wirings parallel to one side of the resin substrate on a main surface of the resin substrate of the power storage device, and wirings having different polarities from each other among the first wirings Are arranged so as to be adjacent to each other, and the first wiring having the same polarity is connected by a first bus wiring orthogonal to the first wiring, and the first solid state battery is adjacent to the first wiring having a different polarity. A plurality of second wires parallel to one side of the resin substrate on the back surface opposite to the main surface of the resin substrate, The wirings having different polarities are arranged adjacent to each other, and the second wirings having the same polarity are connected by a second bus wiring orthogonal to the second wirings, and the second solid state battery has an adjacent polarity. Arranged across the different second wiring It is characterized in that is.

  According to such a configuration, when the flexible substrate is bent, since it has a uniform mounting form, it is preferable that no stress is applied locally.

  In the power storage device according to the present invention, a plurality of the first wirings or the second wirings arranged on the main surface or other than the outermost part on the back surface are partially adjacent to the first wiring or the first wiring. The two wirings have the same polarity.

  According to such a configuration, when the flexible substrate is bent, a short circuit between adjacent solid batteries is prevented and a uniform mounting form is provided. Is preferable because it can be prevented from falling off.

  The power storage device according to the present invention is characterized in that the first solid state battery and the second solid state battery mounted on the flexible substrate are pyramid-shaped solid batteries having a current collector layer, an active material layer, and a solid electrolyte layer. And

  According to such a configuration, since the pyramidal frustum makes the heat applied when mounting on the flexible substrate uniform, dissolution, diffusion, and cooling of the bonding agent at each bonding portion proceed uniformly, and good bonding is achieved. The part can be formed. For this reason, it is preferable because cracks in the joint portion are reduced, and not only can drop and disconnection failure be reduced, but also the Manhattan phenomenon in which the end portion of the solid battery rises from the land can be suppressed.

  According to the present invention, it is possible to provide a highly reliable flexible power storage device in which a solid battery mounted on a flexible substrate at a high density is prevented from dropping and disconnection failure is suppressed.

It is a figure explaining the electrical storage apparatus of this embodiment. It is a figure explaining the wiring on the main surface of the flexible substrate of this embodiment. It is a figure explaining the wiring on the back surface of the flexible substrate of this embodiment. It is a figure explaining the cross section of the electrical storage apparatus of this embodiment. It is a figure explaining the solid battery of this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

<Regarding the structure>
(Power storage device)
FIG. 1 is a plan view showing a power storage device 100 according to the present embodiment, which is a projection when projected from the back side of the surface opposite to the main surface of the flexible substrate 99 constituting the power storage device 100. . As shown in FIG. 1, the power storage device 100 is mainly composed of a flexible substrate 99 and a first solid battery in which a plurality of first solid batteries 96 arranged on the main surface of the flexible substrate 99 are electrically connected. The group 98 includes a second solid battery group 97 in which a plurality of second solid batteries 95 arranged on the back surface opposite to the main surface are electrically connected.

(1 for wiring and land)
FIG. 2 is a diagram when viewed from the main surface side of the flexible substrate 99 used in the power storage device 100 according to the present embodiment. The flexible substrate 99 has a plurality of first wirings 94 that are parallel to the resin substrate, and the plurality of first wirings 94 having the same polarity are orthogonal to the first wirings 94 so as to be connected to the outside. The first bus lines 93 are connected. The first solid state battery 96 is disposed across the first lands 92 provided in the adjacent first wirings 94 having different polarities.

(Regarding wiring and land 2)
FIG. 3 is a view when viewed from the back side opposite to the main surface of the flexible substrate 99 used in the power storage device 100 according to the present embodiment. The flexible substrate 99 has a plurality of second wirings 91 parallel to the resin substrate, and the plurality of second wirings 91 having the same polarity are orthogonal to the second wirings 91 so as to be connected to the outside. The second bus lines 90 are connected. The second solid state battery 95 is disposed across the second lands 89 provided in the adjacent second wirings 91 having different polarities.

(Regarding the arrangement of solid batteries)
FIG. 4 is a cross-sectional view when the first solid battery 96 is solder-mounted on the first land 92 and the second solid battery 95 is solder-mounted on the second land 89. The cross-section at this time is a cross-sectional view of a plane that is perpendicular to the main surface of the flexible substrate 99 and that cuts all the first solid state batteries. As shown in FIG. 4, the first solid battery group 98 composed of a plurality of the first solid batteries 96 is solder-mounted on the first land 92 on the main surface of the flexible substrate 99. On the back surface opposite to the main surface of the flexible substrate 99, the second solid battery group 97 composed of a plurality of the second solid batteries 95 is solder-mounted on the second lands 89 and joined thereto. The unit 88 is connected to the outside.

  In the present embodiment, in the power storage device 100, the first solid battery 96 and the second solid battery 95 have a trapezoidal cross section when cut in a direction perpendicular to the main surface of the flexible substrate 99, and the bottom side is It is the flexible substrate side. The bottom side means the longer side of the two opposite sides parallel to each other in the cross section, that is, the side that is larger than 1 when divided by one side.

  According to this configuration, when the first solid battery 96 and the second solid battery 95 are mounted on the flexible substrate 99, the first land 92 and the first solid formed on the flexible substrate 99 are provided. Since the slope of the junction electrode 88 formed between the terminal electrode 55 of the battery 96 and the second land 89 and the terminal electrode 55 of the second solid battery 95 is gently formed, the flexible substrate 99 is provided. Since the local stress applied to the joint portion 88 when the battery is bent can be avoided and cracks in the joint portion 88 are reduced, dropout and disconnection failure of the first solid battery and the second solid battery can be suppressed. In addition, as long as an effect is not impaired, you may have an unevenness | corrugation in a part of said cross section.

  In this embodiment, when the flexible substrate 99 is projected from the back side, the overlapping area of the first solid battery 96 and the second solid battery 95 is less than half of the mounting area of the first solid battery group 98. It is preferable that

  According to this configuration, the tensile stress caused by the bonding agent generated on the main surface of the flexible substrate 99 and the back surface opposite to the main surface is caused by the first solid battery 96 and the second solid battery. 95 is offset in the overlapping region, and cracks at the joint 88 are further reduced, so that the first solid battery 96 and the second solid battery 95 can be further prevented from dropping off or being disconnected.

In the present embodiment, the flexible substrate 99 includes a plurality of first wirings 94 that are parallel to one side of the flexible substrate 99, and wirings having different polarities from among the first wirings 94 are adjacent to each other. The first wiring 94 having the same polarity is connected by a first bus wiring 93 orthogonal to the first wiring 94, and the first solid state battery 96 is adjacent to the first wiring 94 having a different polarity. A plurality of second wirings 91 parallel to one side of the flexible substrate 99 are provided on the back surface opposite to the main surface of the flexible substrate 99. The second wirings 91 are arranged so that wirings having different polarities from each other are adjacent to each other, and the second wirings 91 having the same polarity are connected by a second bus wiring 90 orthogonal to the second wiring 91. The second solid state battery 95 It is preferably disposed across different second wiring 91 of the adjacent polar.

  According to such a configuration, when the flexible substrate 99 is bent, it has a uniform mounting form, so that the solid battery can be prevented from falling off without being locally stressed.

  In the present embodiment, the power storage device 100 includes a plurality of the first wirings 94 or the second wirings 91 arranged on the main surface or other than the outermost part on the back surface. 94 or the second wiring 91 preferably has the same polarity. That is, in FIG. 2, assuming that the first wiring 94 is a positive electrode wiring, a regular arrangement of a positive electrode, a negative electrode, a negative electrode, a positive electrode, a positive electrode, a negative electrode, a negative electrode, and a positive electrode is provided. Of course, adjacent wirings of the same polarity may be separated into two or may be shared by one.

  According to such a configuration, when the flexible substrate 99 is bent, a short circuit between adjacent solid batteries is prevented and a uniform mounting form is obtained, so that no stress is locally applied and the solid substrate is solid. Battery dropout and disconnection failure can be further suppressed.

  In the present embodiment, the wiring shown in FIG. 2 has a 4-serial 4-parallel wiring structure. Of course, it is possible to freely design a desired voltage and a desired capacity depending on the wiring arrangement, either in series or in parallel. In the case of 4 series and 4 parallel, the first wirings 94 having different polarities may be formed adjacent to each other at a predetermined interval as shown in FIG. A series or parallel circuit can be configured by connecting the first solid state battery 96 between the adjacent first wirings 94.

Further, a parallel circuit can be configured by pulling out the first wirings 94 having different polarities to the opposite sides as shown in FIG.
Furthermore, a series circuit can be configured by combining a plurality of first wires 94 drawn to the opposite sides to form a comb shape. A 4-series 4-parallel circuit can be configured by combining these parallel circuits and series circuits.

  Further, in FIG. 2, a part of the first wiring 94 is adjacent to a wiring having the same polarity, so that a short circuit between solid batteries can be prevented and a more reliable power storage device can be obtained.

  In the present embodiment, the wiring shown in FIG. 3 has a 3 series 4 parallel wiring structure. Of course, it is possible to freely design a desired voltage and a desired capacity depending on the wiring arrangement, either in series or in parallel. In the case of 3 series and 4 parallel, the second wirings 91 having different polarities may be formed adjacent to each other at a predetermined interval as shown in FIG. A series or parallel circuit can be configured by connecting the second solid state battery 95 between the adjacent second wires 91.

Moreover, a parallel circuit can be comprised by drawing out the 2nd wiring 91 from which polarity differs in the other side as shown in FIG.
Furthermore, a series circuit can be configured by combining a plurality of second wirings 91 drawn to the opposite sides to form a comb shape. By combining these parallel circuits and series circuits, a 3 series 4 parallel circuit can be configured.

  Further, in FIG. 3, in a part of the second wiring 91, the same polarity wiring is adjacent to each other, so that a short circuit between the solid batteries can be prevented and a more reliable power storage device can be obtained.

  In the present embodiment, the power storage device 100 includes a current collector layer (positive electrode) in which the first solid battery 96 and the second solid battery 95 are mounted on the main surface of the flexible substrate 99 and the back surface opposite to the main surface. It is a generic name of a current collector layer and a negative electrode current collector layer.), An active material layer (a general name of a positive electrode active material layer and a negative electrode active material layer), and a pyramidal solid battery having a solid electrolyte layer. preferable.

  According to such a configuration, by using the truncated pyramid, the heat applied when mounting on the flexible substrate 99 becomes uniform, so that the dissolution, diffusion, and cooling of the bonding agent proceed uniformly, and a good bonding portion 88 is obtained. Since cracks at the joint portion 88 are reduced, it is possible to reduce the dropout and disconnection failure of the solid state battery. Further, the Manhattan phenomenon in which the end portion of the solid battery is lifted from the land can be suppressed.

(Resin substrate)
As a material that can be used for the above-described resin substrate, resin materials such as polyether sulfone, polycarbonate, polyarylate, polyethylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, and polyester can be used. As the flexible substrate 99, a substrate made of a resin material such as a flexible printed circuit board can be used, so that a thin layer, a light weight and high strength can be maintained as compared with the case where glass or a metal material is used. Flexibility can be provided. As a result, the power storage device can be made thinner and lighter, which is preferable for application to wearable portable electronic devices.

(Wiring and land)
The material that can be used for the wiring and the land is not particularly limited as long as it is a conductive material. However, since tracking is required when the flexible substrate 99 is bent and bent, the malleability and ductility are improved. An excellent material is preferred. For example, it is preferable to use metals such as gold, platinum, copper, aluminum, titanium, stainless steel, iron, and zinc, and alloys thereof.

(Connection between land and solid state battery)
In order to electrically connect the first solid battery 96 and the second solid battery 95 to the first land 92 and the second land 89, respectively, a known mounting technique can be used. Specifically, solder, solder paste, lead-free solder, lead-free solder paste, conductive paste, thermosetting conductive paste, anisotropic conductive paste, metal-containing resin, etc. Good.

(Structure of solid battery)
Next, the solid state battery used in the power storage device of this embodiment will be described. FIG. 5 is a cross-sectional view of the first solid state battery 96 and the second solid state battery 95 mounted on the power storage device according to the present embodiment. As shown in FIG. 5, the first solid battery 96 and the second solid battery 95 are trapezoidal in cross section, and the solid electrolyte layer 50, the positive electrode current collector layer 51, the positive electrode active material layer 52, the negative electrode current collector layer 53, It is composed of a negative electrode active material layer 54 and a terminal electrode 55, and each has a laminated structure. An intermediate layer for relaxing the thermal expansion coefficient may be provided between the positive electrode active material layer 52 and the solid electrolyte layer 50 and between the negative electrode active material layer 54 and the solid electrolyte layer 50.

  The composition of the positive electrode current collector layer 51 and the negative electrode current collector layer 53 is not particularly limited. For example, in addition to the conductive material, an active material, a solid electrolyte, and a sintering aid may be included.

  The compositions of the positive electrode active material layer 52 and the negative electrode active material layer 54 are not particularly limited. For example, a solid electrolyte, a sintering aid, and a conductive material may be included in addition to the active material.

  The composition of the solid electrolyte layer 50 is not particularly limited. For example, a sintering aid may be included in addition to the solid electrolyte.

  There is no clear distinction between the active materials constituting the positive electrode active material layer 52 and the negative electrode active material layer 54, and the potential of two kinds of compounds is compared, and a compound showing a more noble potential is used as the positive electrode active material layer 52. Thus, a compound having a lower potential can be used as the negative electrode active material layer 54. Moreover, you may be comprised with one type of compound.

<About materials>
(Solid electrolyte)
As the solid electrolyte constituting the solid electrolyte layer 50 of the first solid battery 96 and the second solid battery 95, it is preferable to use a material having low electron conductivity and high lithium ion conductivity. For example, perovskite type compounds such as La _0.5 Li _0.5 TiO ₃ , silicon type compounds such as Li ₁₄ Zn (GeO ₄ ) ₄ , garnet type compounds such as Li ₇ La ₃ Zr ₂ O ₁₂ , Li _1. NASICON compounds such as ₃ Al _0.3 Ti _1.7 (PO ₄ ) ₃ and Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ , Li _3.25 Ge _0.25 P _0.75 Thiolicone type compounds such as S ₄ and Li ₃ PS ₄ , glass compounds such as Li ₂ S—P ₂ S ₅ and Li ₂ O—V ₂ O ₅ —SiO ₂ , Li ₃ PO ₄ and Li _3.5 Si _0. It is desirable that it is at least one selected from the group consisting of phosphoric acid compounds such as ₅ P _0.5 O ₄ and Li _2.9 PO _3.3 N _0.46 .

(Current collector material)
Specific examples of the conductive material constituting the positive electrode current collector layer 51 and the negative electrode current collector layer 53 include gold (Au), platinum (Pt), platinum (Pt) -palladium (Pd), silver (Ag), Silver (Ag) -palladium (Pd), aluminum (Al), copper (Cu), indium-tin oxide film (ITO), and the like can be given.

(Positive electrode active material and negative electrode active material)
As the positive electrode active material and the negative electrode active material constituting the positive electrode active material layer 52 and the negative electrode active material layer 54 of the first solid battery 96 and the second solid battery 95, a material that efficiently releases and adsorbs lithium ions is used. preferable. For example, it is preferable to use a transition metal oxide or a transition metal composite oxide. Specifically, the lithium manganese composite oxide _{Li 2 Mn x3 Ma 1-x3} O 3 (0.8 ≦ x3 ≦ 1, Ma = Co, Ni), lithium cobaltate (LiCoO _2), lithium nickelate (LiNiO ₂ ), Lithium manganese spinel (LiMn ₂ O ₄ ), and a general formula: LiNi _x4 Co _y4 Mn _z4 O ₂ (x4 + y4 + z4 = 1, 0 ≦ x4 ≦ 1, 0 ≦ y4 ≦ 1, 0 ≦ z4 ≦ 1) Composite metal oxide, lithium vanadium compound (LiV ₂ O ₅ ), olivine type LiMbPO ₄ (where Mb is one or more selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, Zr) Element), lithium vanadium phosphate (Li ₃ V ₂ (PO ₄ ) ₃ or LiVOPO ₄ ), Li-rich solid solution positive electrode Li ₂ MnO ₃ -L iMcO ₂ (Mc = Mn, Co, Ni), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), Li _a Ni _x5 Co _y5 Al _z5 O ₂ (0.9 <a <1.3, 0.9 <x5 + y5 + z5) It is preferably any of the composite metal oxides represented by <1.1).

(Sintering aid)
Sintering aid added to the solid electrolyte layer 50, the positive electrode current collector layer 51, the positive electrode active material layer 52, the negative electrode current collector layer 53, and the negative electrode active material layer 54 constituting the first solid battery 96 and the second solid battery 95. The type of the agent is not particularly limited as long as the sintering can be performed at a low temperature, but a lithium compound such as Li ₂ CO ₃ or LiOH, a boron compound such as H ₃ BO _3, or a compound composed of lithium and boron is used. It is good to use. These materials are preferable because the compound form is hardly changed by water or carbon dioxide, and can be weighed in the air, and lithium and boron can be easily and accurately added.

  The addition amount of the sintering aid is not limited as long as the characteristics are not impaired. Particularly, in the case of a lithium compound, lithium is 4.38 mol% to 13.34 mol% with respect to the positive electrode active material, the negative electrode active material, and the solid electrolyte. In the case of a compound composed of boron, a range of 0.37 mol% to 1.11 mol% is more preferable.

  The addition amount of the added sintering aid can be analyzed by STEM-EELS analysis that combines a scanning transmission electron microscope and electron energy loss spectroscopy.

<About the process>
(Power storage device)
A lead-free solder paste can be formed on the first land by screen printing using a metal mask designed for the first land formed on the first wiring on the main surface of the flexible substrate. .
The first solid battery is mounted on the lead-free solder paste formed on the first land on the main surface so as to straddle the first wirings having different polarities, and solder mounting is performed through a reflow furnace. The inside of the reflow furnace has a three-stage temperature profile, and includes a first preheat zone, a second main heat zone, and a third cooling zone.
The main surface on which the first solid state battery is mounted is turned over, and lead-free by screen printing using a metal mask designed for the second land formed on the second wiring on the back surface of the flexible substrate. A solder paste can be formed on the second land.
The second solid battery is mounted on the lead-free solder paste formed on the second land on the back surface so as to straddle the second wiring having different polarities, and solder mounting is performed through a reflow furnace. The inside of the reflow furnace has a three-stage temperature profile, and includes a first preheat zone, a second main heat zone, and a third cooling zone. In this manner, a power storage device can be manufactured.
(Method for manufacturing solid battery)
The first solid battery 96 and the second solid battery 95 of the present embodiment include a positive electrode current collector layer 51, a positive electrode active material layer 52, a solid electrolyte layer 50, a negative electrode current collector layer 53, and a negative electrode active material layer 54. Each material is made into a paste, coated and dried to produce a green sheet, the green sheet is laminated, and the produced laminate is simultaneously fired.

  The method for forming the paste is not particularly limited, and for example, a paste can be obtained by mixing the powder of each of the above materials in a vehicle. Here, the vehicle is a general term for the medium in the liquid phase. The vehicle includes a solvent and a binder. By this method, the paste for the positive electrode current collector layer 51, the paste for the positive electrode active material layer 52, the paste for the solid electrolyte layer 50, the paste for the negative electrode current collector layer 53, and the paste for the negative electrode active material layer 54 are obtained. Make it.

  The composition of the paste for the positive electrode current collector layer 51 and the paste for the negative electrode current collector 53 is not particularly limited. For example, in addition to the conductive material, an active material, a solid electrolyte, and a sintering aid may be included. .

  The composition of the paste for the positive electrode active material layer 52 and the paste for the negative electrode active material layer 54 is not particularly limited. For example, in addition to the active material, a solid electrolyte, a sintering aid, and a conductive material may be included.

  The composition of the paste for the solid electrolyte layer 50 is not particularly limited. For example, a sintering aid may be included in addition to the solid electrolyte.

  The prepared paste is applied in a desired order on a base material such as PET (polyethylene terephthalate) and dried as necessary, and then the base material is peeled to prepare a green sheet. The paste application method is not particularly limited, and a known method such as screen printing, application, transfer, doctor blade, or the like can be employed.

The produced green sheets are laminated in a desired order to obtain a laminated substrate.
In the case of producing a parallel type or series-parallel type battery, it is preferable to stack the layers after alignment so that the end surface of the positive electrode active material layer 52 and the end surface of the negative electrode active material layer 54 are accurately stacked. . Further, the laminated structure is not limited to this.

  The produced laminated substrate is crimped together. The pressure bonding is performed while heating, and the heating temperature is, for example, 40 to 90 ° C.

  The obtained laminated substrate is aligned as necessary, and is cut using a tapered blade to produce a laminated body separated into desired dimensions. Although the cutting method is not limited, it may be performed by dicing or knife cutting.

  Chamfering may be performed with a dry green barrel or a wet green barrel before firing the separated laminate.

  In the case of a dry green barrel, it is good to carry out with an abrasive such as alumina, zirconia, or resin beads.

  In the case of a wet green barrel, a solvent is used in addition to an abrasive such as alumina, zirconia, and resin beads. As the solvent at that time, for example, ion-exchanged water, pure water, a fluorine-based solvent, or the like can be used. Further, a lithium salt such as lithium chloride may be dissolved.

  Before firing the singulated laminate, the terminal electrode 55 may be formed and then fired.

  For example, the laminated body is heated and fired in an air atmosphere to obtain a sintered body. In the manufacture of the first solid battery 96 and the second solid battery 95 of the present embodiment, the firing temperature is preferably in the range of 600 to 1200 ° C. If the temperature is lower than 600 ° C., the firing does not proceed sufficiently, and if it exceeds 1200 ° C., problems such as melting of the solid electrolyte and changes in the structure of the positive electrode active material and the negative electrode active material occur. Furthermore, it is more preferable to set it as the range of 700-1100 degreeC. A range of 700 to 1100 ° C. is more suitable for promoting firing and reducing manufacturing costs. The firing time is, for example, 1 to 3 hours. Moreover, you may provide the debuy process which burns off a binder in a part of temperature rising process of baking.

  When the obtained sintered body is not subjected to green barrel before firing, chamfering may be performed with a barrel after dry firing or a barrel after wet firing.

  In the case of barrel after dry firing, it is preferable to carry out with a polishing agent such as alumina, zirconia, or resin beads.

  In the case of the barrel after wet firing, a solvent is used in addition to the abrasive such as alumina, zirconia, and resin beads. For example, ion-exchanged water, pure water, or a fluorine-based solvent may be used as the solvent at that time. Further, a lithium salt such as lithium chloride may be dissolved.

  When the terminal electrode 55 is not formed before firing, the terminal electrode 55 may be formed on the obtained sintered body and heat-treated again to provide the terminal electrode 55.

  A method for forming the terminal electrode 55 is not limited, but a known film formation technique can be used. Specific examples of materials that can be used for the terminal electrode 55 include gold (Au), platinum (Pt), platinum (Pt) -palladium (Pd), silver (Ag), and silver (Ag) -palladium (Pd). , Aluminum (Al), copper (Cu), indium, indium-tin oxide film (ITO), and the like.

  In addition, the terminal electrode 55 may be formed by a thermosetting conductive paste obtained by mixing particles of the conductive material with a thermosetting resin into a paste.

  The terminal electrode 55 may be plated. The plating method and the type of coating are not particularly limited. For example, after forming a Ni coating by electroless Ni plating or electrolytic Ni plating, a Ni-Sn coating is formed by forming a Sn coating by electrotin plating. And good.

  Further, a film made of at least one kind of metal such as Pt, Au, Cu, Ti, Ni, Sn, or an alloy thereof may be formed on the terminal electrode 55 by sputtering.

  The surface of the first solid battery 96 and the second solid battery 95 of the present embodiment may be subjected to water repellent treatment. Although the method of water repellency treatment is not particularly limited, for example, it can be formed by immersing in a solution made of a fluororesin or a silane resin.

  A glass layer may be formed on the surfaces of the first solid battery 96 and the second solid battery 95 of the present embodiment. Although the formation method is not particularly limited, it can be formed by applying a low melting point glass and performing a heat treatment at a desired temperature.

  The power storage device 100 of the present embodiment may be accommodated in a case with high hermeticity. The shape of the case to be accommodated is not limited to a square shape, a cylindrical shape, a coin shape, a card shape or the like.

  The power storage device 100 of this embodiment may be covered with a resin.

  The power storage device 100 of this embodiment may be used in combination with other lithium ion secondary batteries, solar power generation units, wind power generation units, geothermal power generation units, piezoelectric elements, thermoelectric elements, and the like.

Example 1
EXAMPLES The present invention will be described in detail below using examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, a part display is a weight part.

(Production of active material)
Li ₂ MnO ₃ produced by the following method was used as the active material. Li ₂ CO ₃ and MnCO ₃ were used as starting materials, these were weighed so as to have a molar ratio of 2: 1, wet-mixed in a ball mill for 16 hours using water as a solvent, and then dehydrated and dried. The obtained powder was calcined in air at 800 ° C. for 2 hours. The calcined product was coarsely pulverized, wet pulverized with a ball mill for 16 hours using water as a solvent, and then dehydrated and dried to obtain an active material powder. The average particle size of this powder was 0.40 μm. It was confirmed using an X-ray diffractometer that the composition of the produced powder was Li ₂ MnO ₃ .

(Production of active material paste)
The active material paste was prepared by adding 15 parts of ethyl cellulose as a binder and 65 parts of dihydroterpineol as a solvent to 100 parts of this active material powder, and kneading and dispersing with three rolls.

(Preparation of solid electrolyte sheet)
As a solid electrolyte, Li _3.5 Si _0.5 P _0.5 O ₄ produced by the following method was used. Using Li ₂ CO ₃ , SiO ₂ and Li ₃ PO ₄ as starting materials, these were weighed to a molar ratio of 2: 1: 1, wet mixed with a ball mill for 16 hours using water as a solvent, and then dehydrated and dried. did. The obtained powder was calcined in air at 950 ° C. for 2 hours. The calcined product was coarsely pulverized, wet-ground with a ball mill for 16 hours using water as a solvent, and then dehydrated and dried to obtain a solid electrolyte powder. The average particle size of this powder was 0.49 μm. It was confirmed using an X-ray diffractometer that the composition of the produced powder was Li _3.5 Si _0.5 P _0.5 O ₄ .

  Next, 100 parts of ethanol and 200 parts of toluene were added to 100 parts of the powder by a ball mill and wet mixed. Thereafter, 16 parts of polyvinyl butyral binder and 4.8 parts of benzylbutyl phthalate were further added and mixed to prepare a solid electrolyte paste. This solid electrolyte paste was formed into a sheet using a PET film as a base material by a doctor blade method to obtain a solid electrolyte sheet having a thickness of 9 μm.

(Preparation of current collector paste)
After mixing Ag / Pd with a weight ratio of 70/30 and Li ₂ MnO ₃ as a current collector so as to have a volume ratio of 60:40, 10 parts of ethyl cellulose as a binder and 50 parts of dihydroterpineol as a solvent were added. A current collector paste was prepared by kneading and dispersing with three rolls. Here, Ag / Pd having a weight ratio of 70/30 was a mixture of Ag powder (average particle size 0.3 μm) and Pd powder (average particle size 1.0 μm).

(Create terminal electrode paste)
Silver powder, epoxy resin, and solvent were kneaded and dispersed with three rolls to produce a thermosetting conductive paste.

  Using these pastes, lithium ion secondary batteries were produced as follows.

(Preparation of positive electrode active material unit)
A positive electrode active material paste was printed on the solid electrolyte sheet with a thickness of 5 μm by screen printing. Next, the printed positive electrode active material paste was dried at 80 ° C. for 10 minutes, and a positive electrode current collector paste was printed thereon with a thickness of 5 μm by screen printing. Next, the printed positive electrode current collector paste was dried at 80 ° C. for 10 minutes, and the positive electrode active material paste was printed again thereon by screen printing to a thickness of 5 μm. The printed positive electrode active material paste was dried at 80 ° C. for 10 minutes, and then the PET film was peeled off. In this manner, a positive electrode active material unit sheet in which the positive electrode active material paste, the positive electrode current collector paste, and the positive electrode active material paste were printed and dried in this order on the solid electrolyte sheet was obtained.

(Preparation of negative electrode active material unit)
On the solid electrolyte sheet, a negative electrode active material paste was printed with a thickness of 5 μm by screen printing. Next, the printed negative electrode active material paste was dried at 80 ° C. for 10 minutes, and a negative electrode current collector paste was printed thereon with a thickness of 5 μm by screen printing. Next, the printed negative electrode current collector paste was dried at 80 ° C. for 10 minutes, and further, the negative electrode active material paste was printed again by screen printing at a thickness of 5 μm. The printed negative electrode active material paste was dried at 80 ° C. for 10 minutes, and then the PET film was peeled off. In this way, a negative electrode active material unit sheet in which the negative electrode active material paste, the negative electrode current collector paste, and the negative electrode active material paste were printed and dried in this order on the solid electrolyte sheet was obtained.

(Production of laminate)
One positive electrode active material unit and one negative electrode active material unit were stacked with a solid electrolyte interposed therebetween. At this time, the positive electrode current collector paste layer of the first positive electrode active material unit extends only on one end surface, and the negative electrode current collector paste layer of the second negative electrode active material unit extends only on the other end surface. As you did, each unit was staggered and stacked. A solid electrolyte sheet was stacked on both surfaces of the stacked unit so as to have a thickness of 500 μm, and thereafter, this was molded at a temperature of 80 ° C. and a pressure of 1000 kgf / cm 2 [98 MPa] to prepare a stacked body.
(Division and firing of the laminate)
Next, the laminated body was divided into individual laminated blocks by cutting with a dicing saw using a double-edged blade with a taper angle of 30 degrees. Thereafter, the laminated block was simultaneously fired to obtain a sintered body. In the simultaneous firing, the temperature was raised to 800 ° C. at a rate of temperature rise of 200 ° C./hour in the air, kept at that temperature for 2 hours, and naturally cooled after firing. The appearance size of the sintered body after the co-firing was 3.7 mm × 3.2 mm × 0.4 mm. Further, in the cross section when the obtained sintered body is cut in a direction perpendicular to the planes parallel to each other, the longer side of the two opposite sides parallel to each other is the lower base, and the other is the upper base. In this case, the two base angles at both ends of the lower base were each about 75 degrees. The base angle of the produced sintered body was measured using a projector.

(Terminal electrode formation process)
A thermosetting conductive terminal electrode paste was applied to the end face of the sintered body, and thermosetting was performed at 150 ° C. for 30 minutes to form a pair of terminal electrodes.

  A surface other than the terminal electrode was masked, and a film was formed on the terminal electrode in the order of Ni, Cu, and Sn by sputtering to obtain a truncated pyramid solid battery.

The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A flexible substrate having a width of 30 mm and a length of 80 mm, which was designed to be 1/2 of the above, was prepared.
Here, the mounting area refers to the bottom area obtained by the vertical length x horizontal length of the bottom base of the truncated pyramid solid battery to be mounted. Each example is shown in Table 1.
First, a lead-free solder paste was formed on each land by screen printing using a metal mask designed in accordance with the land formed on the main surface of the flexible substrate.
The long bottom side of the truncated pyramid solid battery was mounted on a lead-free solder paste formed on the land, and solder mounting was performed through a reflow furnace. The reflow furnace has a generally three-step temperature profile, passing through the first 170 ° C. preheat zone over 300 seconds, passing through the second 270 ° C. main heat zone in 60 seconds, By cooling the cooling zone over 600 seconds, 28 pyramidal solid batteries were mounted on the main surface.
The main surface side on which the pyramid-shaped solid battery is mounted is turned over, and a lead-free solder paste is formed on each land by screen printing using a metal mask designed for the land formed on the back surface. A solid pyramidal solid battery is mounted on the back surface in the same manner as the main surface side, except that the long bottom side of the same size pyramid solid battery is mounted on a lead-free solder paste and solder mounting is performed. Individually mounted to obtain a power storage device.

(Example 2)
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1/3 of the above was used.

(Example 3)
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1/4 of the above was used.

Example 4
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1 / 5.5 of the above was used.

(Example 5)
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1/10 of the above was used.

(Example 6)
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1/12 of the above was used.

(Example 7)
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1/20 of that was used.

(Example 8)
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1/40 of that of the first example was used.

Example 9
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1 / 1.5 of that of the first example was used.

(Example 10)
The overlapping area of the first solid state battery mounted on the main surface is the overlapping area of the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface. A power storage device was manufactured in the same manner as in Example 1 except that a flexible substrate designed to be 1 / 1.3 of that was used.

(Example 11)
Except for using a flexible substrate designed so that the first solid state battery mounted on the main surface of the flexible substrate and the second solid state battery mounted on the back surface opposite to the main surface completely overlap each other. A power storage device was manufactured in the same manner as in Example 1.

(Example 12)
A power storage device was produced in the same manner as in Example 11 except that a laminated body was cut using a double-edged blade with a blade edge angle of 60 degrees and a blade was cut to produce a truncated pyramid solid battery.

(Example 13)
A power storage device was produced in the same manner as in Example 1 except that the laminated body was cut by using a double-edged blade with a blade edge angle of 60 degrees and a blade was cut to produce a truncated pyramid solid battery.

(Example 14)
A power storage device was produced in the same manner as in Example 5 except that a laminated body was cut by using a double-edged blade with a blade edge angle of 60 degrees and a blade was cut to produce a truncated pyramid solid battery.

(Example 15)
A power storage device was produced in the same manner as in Example 11 except that a laminated body was cut using a double-edged blade with a blade edge angle of 90 degrees and a truncated pyramid solid battery was produced.

(Example 16)
A power storage device was produced in the same manner as in Example 1 except that a laminated body was cut by using a double-edged blade with a blade edge taper of 90 degrees to produce a truncated pyramid solid battery.

(Example 17)
A power storage device was produced in the same manner as in Example 5 except that a laminated body was cut by using a double-edged blade with a blade edge taper of 90 degrees to produce a truncated pyramid solid battery.

(Comparative Example 1)
A power storage device was produced in the same manner as in Example 11 except that a rectangular solid battery produced by cutting the laminate using a dicing blade having no taper was mounted.

(Test method)
One end of a power storage device in which a solid battery is mounted on a flexible substrate is fixed, and the opposite end is twisted 60 degrees to the left and right, 60 times per minute for 6 hours. The defect rate was evaluated from the number and the number of solid batteries mounted on the main surface and the back surface. The results are shown in Table 1.

  In the power storage devices after the tests of Examples 1 to 17 and Comparative Example 1, it was confirmed that the solid battery was detached from the flexible substrate.

  The power storage devices of Examples 1 to 8, Example 13, Example 14, Example 16, and Example 17 exhibited less twisting and twist resistance. In particular, when a pyramid-shaped solid battery having a trapezoidal cross-sectional shape when cut in a direction perpendicular to the main surface was mounted, the solid-state battery did not drop out and showed high torsion resistance.

  By using the arrangement of the present invention, a solid state battery mounted on a flexible substrate at a high density is prevented, and a highly reliable power storage device with suppressed disconnection failure is provided. I can do it.

DESCRIPTION OF SYMBOLS 100 ... Power storage device 99 ... Flexible board 98 ... 1st solid battery group 97 ... 2nd solid battery group 96 ... 1st solid battery 95 ... 2nd solid battery 94 ... 1st wiring 93 ... 1st bus wiring 92 ... 1st 1 land 91 ... 2nd wiring 90 ... 2nd bus wiring 89 ... 2nd land 88 ... junction 50 ... solid electrolyte layer 51 ... positive electrode current collector layer 52 ... positive electrode active material layer 53 ... negative electrode current collector layer 54 ... negative electrode Active material layer 55 ... terminal electrode

Claims (5)

A first solid battery group configured by electrically connecting a plurality of first solid batteries is mounted on a main surface of a flexible substrate in which wiring is applied to a resin substrate, and the main surface of the flexible substrate A second solid battery group configured by electrically connecting a plurality of second solid batteries is mounted on the back surface on the opposite side,
The first solid battery and the second solid battery have a trapezoidal cross section when cut in a direction perpendicular to the main surface, and the long base side of the side of the trapezoid is the flexible substrate side. Power storage device.   2. The power storage device according to claim 1, wherein an area where the first solid battery and the second solid battery overlap when projected from the back side is not more than half of a mounting area of the first solid battery group. . The main surface of the resin substrate of the power storage device has a plurality of first wirings parallel to one side of the resin substrate, and the wirings having different polarities among the first wirings are adjacent to each other,
The first wiring having the same polarity is connected by a first bus wiring orthogonal to the first wiring, and the first solid state battery is disposed across the adjacent first wirings having different polarities. In addition, a plurality of second wirings parallel to one side of the resin substrate are provided on the back surface opposite to the main surface of the resin substrate, and wirings having different polarities from among the second wirings are adjacent to each other. The second wirings having the same polarity are connected by a second bus wiring orthogonal to the second wiring, and the second solid state battery straddles adjacent second wirings having different polarities. The power storage device according to claim 1 or 2, wherein   A plurality of the first wirings or the second wirings arranged on the main surface or other than the outermost part on the back surface have the same polarity in the adjacent first wirings or the second wirings. The power storage device according to claim 3. The first solid battery and the second solid battery according to any one of claims 1 to 4 are truncated pyramid solid batteries having a current collector layer, an active material layer, and a solid electrolyte layer. apparatus.

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