Patent Description:
Patent Literature <NUM> discloses a connection structure between an electrode tab and a tab lead in a capacitor such as a lithium-ion battery. Patent Literature <NUM> discloses a nonaqueous solid-electrolyte battery in which a tab lead is connected to a positive electrode and a negative electrode. In Patent Literature <NUM> and <NUM>, a positive electrode tab and a negative electrode tab are arranged in a staggered fashion when viewed from above. Document <CIT> discloses a secondary battery which is small in size and in which current capacity per unit volume can be increased. The secondary battery includes two cell units each including a charging layer between a first electrode layer and a second electrode layer, the two cell units being parallel-connected by juxtaposing and connecting a first electrode layer of one cell unit and a first electrode layer of the other cell unit or a second electrode layer of the one cell unit and a second electrode layer of the other cell unit, and by wire-connecting the second electrode layer of the one cell unit and the second electrode layer of the other cell unit or the first electrode layer of the one cell unit and the first electrode layer of the other cell unit.

For a high-capacity battery, a laminated structure where sheet batteries are laminated together is employed. In this case, if tabs overlap each other, the thickness of the battery increases. To be specific, the thickness of the laminated structure increases because the thickness of a lamination of two sheets is the total thickness of sheets, tab leads, an insulating material, a conductive bonding agent and the like.

Further, if the positions of tab leads are staggered to reduce the thickness, a step of joining tab leads is needed, which decreases productivity. Further, if tab leads are comb-shaped or the like, a step of lamination becomes complicated, which also decreases productivity.

The present invention has been accomplished to solve the above problems and an object of the present invention is thus to provide a technique to simplify the structure of a laminated battery.

A laminated battery according to one aspect of this embodiment is a secondary battery in which a plurality of sheet batteries are laminated, which includes a first sheet battery, a second sheet battery, a third sheet battery and a fourth sheet battery, each including a first electrode on a front side surface and a second electrode on a back side surface, in which when viewed from above in a state where the first sheet battery, the second sheet battery, the third sheet battery and the fourth sheet battery are laminated, the first sheet battery includes a first tab part placed so as to project outward of the second sheet battery, and the second sheet battery includes a second tab part placed so as to project outward of the first sheet battery in a state where the second electrode of the first sheet battery and the second electrode of the second sheet battery are placed face-to-face to each other, the third sheet battery includes a third tab part placed so as to project outward of the fourth sheet battery, and the fourth sheet battery includes a fourth tab part placed so as to project outward of the third sheet battery in a state where the second electrode of the third sheet battery and the second electrode of the fourth sheet battery are placed face-to-face to each other, and the first tab part and the fourth tab part overlap each other so that the second electrode on the surface of the first tab part and the second electrode on the surface of the fourth tab part are placed face-to-face to each other.

In the above-described laminated battery, the second electrode on the surface of the first tab part and the second electrode on the surface of the fourth tab part may be connected through a conductive bonding agent.

In the above-described laminated battery, a thickness of the conductive bonding agent may be equal to a total thickness of the second sheet battery and the third sheet battery.

In the above-described laminated battery, the first to fourth sheet batteries may be laminated and folded without folding the first tab part, the second tab part, the third tab part and the fourth tab part.

In the above-described laminated battery, each of the first sheet battery, the second sheet battery, the third sheet battery and the fourth sheet battery may include a base material serving as the first electrode, and peripheral parts of the base materials of the first sheet battery, the second sheet battery, the third sheet battery and the fourth sheet battery may be bonded together.

In the above-described laminated battery, the second tab part and the third tab part are placed so as to overlap each other when viewed from above in a state where the first to fourth sheet batteries are laminated.

In the above-described laminated battery, the laminated battery may further include a fifth sheet battery and a sixth sheet battery, each including a first electrode on a front side surface and a second electrode on a back side surface, wherein when viewed from above in a state where the first to sixth sheet batteries are laminated, the fifth sheet battery may include a fifth tab part placed so as to project outward of the sixth sheet battery, and the sixth sheet battery may include a sixth tab part placed so as to project outward of the fifth sheet battery in a state where the second electrode of the fifth sheet battery and the second electrode of the sixth sheet battery are placed face-to-face to each other, and the third tab part and the sixth tab part may overlap each other so that the second electrode on the surface of the third tab part and the second electrode on the surface of the sixth tab part are placed face-to-face to each other and connected.

In the above-described laminated battery, the second electrode on the surface of the third tab part and the second electrode on the surface of the sixth tab part may be connected through a conductive bonding agent.

In the above-described laminated battery, the first electrode of the second sheet battery and the first electrode of the third sheet battery may be placed face-to-face to each other and connected.

In the above-described laminated battery, a first insulating material may be formed on the first sheet battery, a second insulating material may be formed on the second sheet battery, a third insulating material may be formed on the third sheet battery, a fourth insulating material may be formed on the fourth sheet battery, the first insulating material may be formed in close proximity to the second tab part, the second insulating material may be formed in close proximity to the first tab part, the third insulating material may be formed in close proximity to the fourth tab part, and the fourth insulating material may be formed in close proximity to the third tab part.

In the above-described laminated battery, the first to fourth sheet batteries may include rectangular parts placed so as to overlap each other when viewed from above in a state where the first to fourth sheet batteries are laminated, the first to fourth tab parts may project outward from one side of the rectangular parts.

In the above-described laminated battery, the first to fourth sheet batteries may include rectangular parts placed so as to overlap each other when viewed from above in a state where the first to fourth sheet batteries are laminated, the first tab part and the fourth tab part may project outward from a first side of the rectangular parts, and the second tab part and the third tab part may project outward from a second side opposed to the first side.

In the above-described laminated battery, each of the first to fourth sheet batteries may include a base material serving as the first electrode, the second electrode may be formed on both surfaces of the base material, and the second electrode of the second sheet battery and the second electrode of the third sheet battery may be placed face-to-face to each other and connected.

According to the present invention, it is possible to provide a technique to simplify the structure of a laminated battery.

Examples of embodiments of the present invention are described hereinafter with reference to the drawings. The following description describes preferred embodiments of the present invention, and the technical scope of the present invention is not limited to the embodiments described below.

<FIG> is a view showing the cross-sectional structure of a sheet battery <NUM>, which is a sheet-shaped oxide semiconductor secondary battery.

In <FIG>, the sheet battery <NUM> has a laminated structure in which an n-type oxide semiconductor layer <NUM>, a charging layer <NUM>, a p-type oxide semiconductor layer <NUM>, and a second electrode <NUM> are laminated in this order on a base material <NUM>. Note that the laminated structure formed on the base material <NUM> is a laminate <NUM>. Thus, the laminate <NUM> includes the n-type oxide semiconductor layer <NUM>, the charging layer <NUM>, the p-type oxide semiconductor layer <NUM>, and the second electrode <NUM>.

The base material <NUM> is made of a conductive material such as metal or the like, and it functions as a first electrode. In this embodiment, the base material <NUM> acts as a negative electrode. For example, a metallic foil sheet such as an SUS sheet or an aluminum sheet may be used as the base material <NUM>.

Alternatively, the base material <NUM> made of an insulating material may be prepared, and the first electrode may be formed on the base material <NUM>. The base material <NUM> may have any structure as long as it includes the first electrode. In the case of forming the first electrode on the base material <NUM>, a metallic material such as chromium (Cr) or titanium (Ti) may be used as a material of the first electrode. An ally film containing aluminum (Al), silver (Ag) or the like may be used as a material of the first electrode. When forming the first electrode on the base material <NUM>, it can be formed in the same manner as that by which the second electrode <NUM> is formed, which is described later.

The n-type oxide semiconductor layer <NUM> is formed on the base material <NUM>. The n-type oxide semiconductor layer <NUM> is formed so as to contain an n-type oxide semiconductor material (a second n-type oxide semiconductor material). For example, titanium dioxide (TiO<NUM>), tin oxide (SnO<NUM>), zinc oxide (ZnO) or the like can be used as the n-type oxide semiconductor layer <NUM>. The n-type oxide semiconductor layer <NUM> may be deposited on the base material <NUM> by, for example, sputtering or vapor deposition. It is preferred to use titanium dioxide (TiO<NUM>) as a material of the n-type oxide semiconductor layer <NUM>.

The charging layer <NUM> is formed on the n-type oxide semiconductor layer <NUM>. The charging layer <NUM> is made of a mixture of an insulating material and an n-type oxide semiconductor material. For example, as an n-type oxide semiconductor material (a first n-type oxide semiconductor material) of the charging layer <NUM>, fine particles of n-type oxide semiconductor may be used. The photoexcited structure of the n-type oxide semiconductor is changed by exposure to ultraviolet radiation and becomes a layer with a charging function. Silicone resin may be used as an insulating material of the charging layer <NUM>. For example, it is preferred to use a silicon compound (silicone) with a basic skeleton having a siloxane bond of silicon oxide or the like as an insulating material.

For example, the charging layer <NUM> is made of oxide silicon and titanium dioxide where the first n-type oxide semiconductor material is titanium dioxide. Other preferred n-type oxide semiconductor materials that can be used for the charging layer <NUM> are tin oxide (SnO<NUM>) and zinc oxide (ZnO). A material composed of a combination of two or all of titanium dioxide, tin oxide and zinc oxide may be used.

A fabrication process of the charging layer <NUM> is described hereinafter. First, a coating liquid made by mixing a solvent with a mixture of a precursor of titanium oxide, tin oxide or zinc oxide and silicone oil is prepared. Further, a coating liquid made by mixing fatty acid titanium and silicone oil with a solvent is prepared. Then, the coating liquid is applied over the n-type oxide semiconductor layer <NUM> by spin coating, slit coating or the like. The coating film is then dried and baked, thereby forming the charging layer <NUM> on the n-type oxide semiconductor layer <NUM>. Note that an example of a precursor is titanium stearate, which is a precursor of titanium oxide. Titanium oxide, tin oxide and zinc oxide are formed by being resolved from aliphatic acid chloride, which is a precursor of metallic oxide. The charging layer <NUM> after drying and baking may be exposed to ultraviolet radiation so that it is UV cured.

Note that, for titanium oxide, tin oxide, zinc oxide and the like, fine particles of an oxide semiconductor may be used instead of using a precursor. A mixed solution is made by mixing nanoparticles of titanium oxide or zinc oxide with silicone oil. Further, a coating liquid is made by mixing a solvent with the mixed solution. The coating liquid is applied over the n-type oxide semiconductor layer <NUM> by spin coating, slit coating or the like. The coating film is then dried, baked and UV-exposed, thereby forming the charging layer <NUM>.

The first n-type oxide semiconductor material contained in the charging layer <NUM> and the second n-type oxide semiconductor material contained in the n-type oxide semiconductor layer <NUM> may be the same or different. For example, when the n-type oxide semiconductor material contained in the n-type oxide semiconductor layer <NUM> is tin oxide, the n-type oxide semiconductor material in the charging layer <NUM> may be tin oxide or an n-type oxide semiconductor material other than tin oxide.

The p-type oxide semiconductor layer <NUM> is formed on the charging layer <NUM>. The p-type oxide semiconductor layer <NUM> is formed so as to contain a p-type oxide semiconductor material. Nickel oxide (NiO), copper aluminum oxide (CuAlO<NUM>) or the like can be used as a material of the p-type oxide semiconductor layer <NUM>. For example, the p-type oxide semiconductor layer <NUM> may be a nickel oxide layer with a thickness of <NUM>. The p-type oxide semiconductor layer <NUM> is deposited on the charging layer <NUM> by a deposition method such as vapor deposition or sputtering.

The second electrode <NUM> may be formed using a conductive film. A metallic material such as chromium (Cr) or copper (Cu) may be used as a material of the second electrode <NUM>. Another example of a metallic material is a silver (Ag) alloy containing aluminum (Al) or the like. A method of formation may be a vapor-phase deposition such as sputtering, ion plating, electron beam evaporation, vacuum deposition or chemical vapor deposition. Further, a metallic electrode may be formed by electroplating, electroless plating or the like. A metal that is used for plating is typically copper, copper alloy, nickel, aluminum, silver, gold, zinc, tin or the like. For example, the second electrode <NUM> is an Al film with a thickness of <NUM>.

Although the n-type oxide semiconductor layer <NUM> is placed under the charging layer <NUM>, and the p-type oxide semiconductor layer <NUM> is placed on top of the charging layer <NUM> in the above description, the positions of the n-type oxide semiconductor layer <NUM> and the p-type oxide semiconductor layer <NUM> may be interchanged. Specifically, the n-type oxide semiconductor layer <NUM> may be placed on top of the charging layer <NUM>, and the p-type oxide semiconductor layer <NUM> may be placed under the charging layer <NUM>. In this case, the base material <NUM> acts as a positive electrode, and the second electrode <NUM> acts as a negative electrode. Thus, on top of the charging layer <NUM> may be any of the n-type oxide semiconductor layer <NUM> and the p-type oxide semiconductor layer <NUM> as long as the charging layer <NUM> is interposed between the n-type oxide semiconductor layer <NUM> and the p-type oxide semiconductor layer <NUM>. In other words, the sheet battery <NUM> has a structure where the first electrode (the base material <NUM>), the first conductivity type oxide semiconductor layer (the n-type oxide semiconductor layer <NUM> or the p-type oxide semiconductor layer <NUM>), the charging layer <NUM>, the second conductivity type oxide semiconductor layer (the p-type oxide semiconductor layer <NUM> or the n-type oxide semiconductor layer <NUM>), and the second electrode <NUM> are laminated in this order from the bottom.

Further, the sheet battery <NUM> may have a structure that includes a layer other than the first electrode (the base material <NUM>), the first conductivity type oxide semiconductor layer (the n-type oxide semiconductor layer <NUM> or the p-type oxide semiconductor layer <NUM>), the charging layer <NUM>, the second conductivity type oxide semiconductor layer (the p-type oxide semiconductor layer <NUM> or the n-type oxide semiconductor layer <NUM>), and the second electrode <NUM>.

As described above, the laminate <NUM> that includes the n-type oxide semiconductor layer <NUM>, the charging layer <NUM>, the p-type oxide semiconductor layer <NUM> and the second electrode <NUM> is placed on top of the base material <NUM>. Thus, the uppermost surface of the sheet battery <NUM> is the second electrode <NUM>. Note that the laminate <NUM> is not at the edge of the sheet battery <NUM>. The laminate <NUM> is formed substantially all over the base material <NUM> except for the edge of its surface. Thus, the base material <NUM> is exposed to the outside at the edge of the sheet battery <NUM>. In other words, the outside of the laminate <NUM> (i.e., the periphery of the base material <NUM>) is an exposure position where the base material <NUM> is exposed to the outside. The base material <NUM> is the uppermost surface of the sheet battery <NUM> on the periphery of the sheet battery <NUM>.

The secondary battery according to this embodiment has a structure where the sheet batteries <NUM> shown in <FIG> are laminated together, thus having a high capacity. To be specific, a plurality of sheet batteries <NUM> are connected in parallel, thereby increasing the capacity of the secondary battery. To this end, the sheet batteries <NUM> are laminated face-to-face in this embodiment.

In this embodiment, two types of sheet batteries are prepared. The two types of sheet batteries are the same in laminated structure and different in planar shape. <FIG> shows the planar shapes of two types of sheet batteries. In <FIG>, one of the two types of sheet batteries is type-I sheet battery <NUM>, and the other is type-II sheet battery <NUM>. In <FIG>, a plane on which the sheet batteries <NUM> and <NUM> are placed is an X-Y plane. The X direction and the Y direction are orthogonal to each other. Further, <FIG> shows the planar shapes of the sheet batteries <NUM> and <NUM> when viewed from the laminate <NUM> side (the upper side of <FIG>).

The planar shape of the type-I sheet battery <NUM> on the X-Y plane is described first. As shown in <FIG>, the sheet battery <NUM> has a rectangular part <NUM> and a tab part <NUM>. The rectangular part <NUM> may be oblong or square on the X-Y plane. In this example, the rectangular part <NUM> has an oblong shape having sides parallel to the X direction and the Y direction, with their longer sides along the X direction. The tab part <NUM> juts out in the +Y direction from the rectangular part <NUM>. Specifically, the tab part <NUM> projects outward from one side along the X direction of the rectangular part <NUM>. In this example, the sheet battery <NUM> is inverted L-shaped on the X-Y plane. The tab part <NUM> is formed at the +X and +Y side edge of the rectangular part <NUM>.

A base material <NUM> in <FIG> corresponds to the base material <NUM> in <FIG>. Likewise, a laminate <NUM> in <FIG> corresponds to the laminate <NUM> in <FIG>. Thus, the laminate <NUM> includes the n-type oxide semiconductor layer <NUM>, the charging layer <NUM>, the p-type oxide semiconductor layer <NUM> and the second electrode <NUM> as shown in <FIG>.

A major part of the laminate <NUM> is formed in the rectangular part <NUM> and the tab part <NUM>. Thus, the uppermost surface is the second electrode <NUM> in the most part of the rectangular part <NUM> and the tab part <NUM>. In the area where the laminate <NUM> is not placed, the base material <NUM> is exposed to the outside. Therefore, the uppermost surface is the base material <NUM> in the peripheral part of the sheet battery <NUM>.

Further, an insulating material <NUM> is formed on the sheet battery <NUM>. As shown in <FIG>, the insulating material <NUM> is formed as a part of the rectangular part <NUM>. To be specific, the tab part <NUM> is formed at the +X and +Y side edge of the rectangular part <NUM>, and the insulating material <NUM> is formed at the -X and +Y side edge of the rectangular part <NUM>. The insulating material <NUM> is placed along the X direction.

The insulating material <NUM> is placed on the outside of the laminate <NUM>. Specifically, the insulating material <NUM> is formed in the area where the uppermost surface is the base material <NUM>. The insulating material <NUM> is formed directly on the base material <NUM> so as to be in contact with the base material <NUM>. The insulating material <NUM> is formed to cover a part of the base material <NUM>. The insulating material <NUM> is coated on the base material <NUM> by vapor deposition, spraying or the like. A resin film such as polyimide, for example, may be used as the insulating material <NUM>. The insulating material <NUM> preferably has elasticity.

The structure of the type-II sheet battery <NUM> is described next. The sheet battery <NUM> has a planar shape that is symmetrical to the sheet battery <NUM>. To be specific, the sheet battery <NUM> and the sheet battery <NUM> are symmetric with respect to a line parallel to the Y direction.

The sheet battery <NUM> has a rectangular part <NUM> and a tab part <NUM>. The rectangular part <NUM> may be oblong or square on the X-Y plane. In this example, the rectangular part <NUM> has an oblong shape having sides parallel to the X direction and the Y direction, with their longer sides along the X direction. The tab part <NUM> juts out in the +Y direction from the rectangular part <NUM>. Specifically, the tab part <NUM> projects outward from one side along the X direction of the rectangular part <NUM>. In this example, the sheet battery <NUM> is inverted L-shaped on the X-Y plane. The tab part <NUM> is formed at the -X and +Y side edge of the rectangular part <NUM>.

A base material <NUM> in <FIG> corresponds to the base material <NUM> in <FIG>. Likewise, a laminate <NUM> in <FIG> corresponds to the laminate <NUM> in <FIG>. Thus, the laminate <NUM> includes the n-type oxide semiconductor layer <NUM>, the charging layer <NUM>, the p-type oxide semiconductor layer <NUM> and the second electrode <NUM> as shown in <FIG>. The laminated construction of the laminate <NUM> is the same as that of the laminate <NUM>.

A major part of the laminate <NUM> is formed in the rectangular part <NUM> and the tab part <NUM>. The uppermost surface is the second electrode <NUM> in the most part of the rectangular part <NUM> and the tab part <NUM>. In the area where the laminate <NUM> is not placed, the base material <NUM> is exposed to the outside. Therefore, the uppermost surface is the base material <NUM> in the peripheral part of the sheet battery <NUM>.

Further, an insulating material <NUM> is formed on the sheet battery <NUM>. As shown in <FIG>, the insulating material <NUM> is formed as a part of the rectangular part <NUM>. To be specific, the tab part <NUM> is formed at the -X and +Y side edge of the rectangular part <NUM>, and the insulating material <NUM> is formed at the +X and +Y side edge of the rectangular part <NUM>. The insulating material <NUM> is placed along the X direction.

The insulating material <NUM> is placed to prevent the base material <NUM> from being short-circuited with the second electrode <NUM> of the other sheet battery <NUM> when the sheet batteries <NUM>, <NUM> are laminated together. Likewise, the insulating material <NUM> is placed to prevent the base material <NUM> from being short-circuited with the second electrode <NUM> of the other sheet battery <NUM> when the sheet batteries <NUM> are laminated together.

Note that the type-I sheet battery <NUM> and the type-II sheet battery <NUM> are different only in the positions of the tab parts <NUM> and <NUM> and the insulating materials <NUM> and <NUM> in the X direction. For example, the rectangular part <NUM> has the same size as the rectangular part <NUM>. Further, the tab part <NUM> has the same size as the tab part <NUM>.

A battery structure where two sheet batteries <NUM> are laminated together is described hereinafter with reference to <FIG>. Hereinafter, the battery structure where two sheet batteries <NUM> are laminated together is described as a sheet pair <NUM>. <FIG> is an exploded perspective view of the sheet pair <NUM>. <FIG> is an X-Z plane view showing the side structure of the sheet pair <NUM>. <FIG> is an X-Y plane view showing the planar shape of the sheet pair <NUM>.

The sheet pair <NUM> has a pair of two sheet batteries 110a and 110b. In the sheet pair <NUM>, the two sheet batteries 110a and 110b are connected. Note that, in the figures described hereinbelow, a plane on which the sheet batteries 110a and 110b are placed is an X-Y plane, just like in <FIG>. Further, a direction orthogonal to the X-Y plane is the Z direction. An XYZ orthogonal coordinate system where the in-plane directions of the sheet batteries 110a and 110b are the X direction and the Y direction and the thickness direction of the sheet pair <NUM> is the Z direction is used in the following description.

Further, for the sake of description, +Z side is the upper side, and the -Z side is the lower side. The sheet battery 110b is placed on the upper side of the sheet battery 110a.

To distinguish between the elements of the two sheet batteries 110a and 110b, the alphabet "a" or "b" is added after the reference numeral. For example, the insulating material <NUM>, the rectangular part <NUM>, the tab part <NUM>, the second electrode <NUM> and the laminate <NUM> included in the sheet battery 110a are the insulating material 143a, the rectangular part 131a, the tab part 132a, the second electrode 17a and the laminate 120a, respectively. Likewise, the insulating material <NUM>, the rectangular part <NUM>, the tab part <NUM>, the second electrode <NUM> and the laminate <NUM> included in the sheet battery 110b are the insulating material 143b, the rectangular part 131b, the tab part 132b, the second electrode 17b and the laminate 120b, respectively. Note that, to clarify the description, the reference symbols of the laminate 120a, 120b and the second electrode 17a, 17b are shown side by side in the figures as appropriate. Further, when there is no need to distinguish between the two sheet batteries 110a and 110b, the alphabet "a" or "b" after the reference numeral is omitted as appropriate.

The sheet pair <NUM> includes the sheet battery 110a, which is a first sheet battery, and the sheet battery 110b, which is a second sheet battery. The tab part 132a of the sheet battery 110a is a first tab part, and the tab part 132b of the sheet battery 110b is a second tab part. Likewise, the insulating material 143a placed in the sheet battery 110a is a first insulating material, and the insulating material 143b placed in the sheet battery 110b is a second insulating material.

The sheet battery 110a and the sheet battery 110b are placed with the second electrodes 17a and 17b facing each other. Thus, the sheet battery 110b is inverted relative to the sheet battery 110a so that the second electrode 17b faces in the -Z direction. To be specific, rotating the sheet battery <NUM> in <FIG> by <NUM>° about the Y axis being the axis of rotation gives the orientation of the sheet battery 110b. The orientation of the sheet battery 110a is the same as that of the sheet battery <NUM> in <FIG>.

The second electrode 17a of the sheet battery 110a is placed facing upward, and the second electrode 17b of the sheet battery 110b is placed facing downward. Thus, as shown in <FIG>, the laminate 120a is placed on the upper side of the base material 111a in the sheet battery 110a, and the laminate 120b is placed on the lower side of the base material 111b in the sheet battery 110b. The sheet battery 110a and the sheet battery 110b are laminated together in such a way that the rectangular part 131a and the rectangular part 131b overlap each other when the XY plane is viewed from above.

In the sheet pair <NUM>, the second electrode 17a of the sheet battery 110a and the second electrode 17b of the sheet battery 110b are placed face-to-face with each other and connected. The second electrode 17a is exposed on the upper surface of the sheet battery 110a, and the second electrode 17b is exposed on the lower surface of the sheet battery 110b. Accordingly, by placing the second electrode 17a of the sheet battery 110a and the second electrode 17b of the sheet battery 110b facing each other, the second electrode 17a and the second electrode 17b come into contact with each other. The second electrode 17a of the sheet battery 110a and the second electrode 17b of the sheet battery 110b thereby become electrically continuous.

Because the sheet battery 110b is inverted relative to the sheet battery 110a, the tab part 132a and the tab part 132b are arranged in a staggered fashion on the X-Y plane. Specifically, the tab part 132a is placed at the +X side edge of the sheet battery 110a, and the tab part 132b is placed at the -X side edge of the sheet battery 110b. In this manner, the position of the tab part 132a and the position of the tab part 132b in the X direction are different. The tab part 132a and the tab part 132b are staggered on the X-Y plane. In other words, the tab part 132a of the sheet battery 110a projects to the outer side of the sheet battery 110b on the X-Y plane. Likewise, the tab part 132b of the sheet battery 110b projects to the outer side of the sheet battery 110a on the X-Y plane.

Further, the insulating material 143b is formed on the lower surface of the sheet battery 110b. The insulating material 143b is placed in close proximity to the tab part 132a. The insulating material 143b is placed at the edge of the sheet battery 110b. A "close" position is a position where the laminate 120b of the sheet battery 110b is not placed and which corresponds to the tab part 132a, for example. The insulating material 143b is placed between the sheet battery 110a and the sheet battery 110b in the position extending to the tab part 132a of the sheet battery 110a. In other words, the insulating material 143b is placed in the area of the rectangular part 131a at the boundary between the tab part 132a and the rectangular part 131a of the sheet battery 110a on the X-Y plane. The insulating material 143b is thereby interposed between the second electrode 17a on the uppermost surface of the laminate 120a in close proximity to the tab part 132a and the base material 111b of the sheet battery 110b. It is thus possible to prevent short-circuit between the second electrode 17a of the sheet battery 110a and the base material 111b of the sheet battery 110b.

Further, the insulating material 143a is formed on the upper surface of the sheet battery 110a. The insulating material 143a is placed in close proximity to the tab part 132a. The insulating material 143a is placed at the edge of the sheet battery 110a. The insulating material 143a is placed between the base material 111a of the sheet battery 110a and the laminate 120b of the sheet battery 110b.

To be specific, the insulating material 143a is formed in a position where the laminate 120a of the sheet battery 110a is not placed and which corresponds to the tab part 132b. The insulating material 143a is placed between the sheet battery 110a and the sheet battery 110b in the position extending to the tab part 132b of the sheet battery 110b. In other words, the insulating material 143a is placed in the area of the rectangular part 131b at the boundary between the tab part 132b and the rectangular part 131b of the sheet battery 110b on the X-Y plane.

The insulating material 143a is thereby interposed between the second electrode 17b on the uppermost surface of the laminate 120b in close proximity to the tab part 132b and the base material 111a of the sheet battery 110a. It is thus possible to prevent short-circuit between the second electrode 17a of the sheet battery 110a and the base material 111b of the sheet battery 110b.

As described above, the tab part 132a and the tab part 132b are staggered in position in the X direction. Therefore, in this embodiment, there is an area where the second electrode <NUM> of one sheet battery <NUM> and the base material <NUM> of the other sheet battery <NUM> face each other at the boundary between the tab part <NUM> and the rectangular part <NUM>. In this embodiment, the insulating material <NUM> is placed in this area. In other words, the insulating material <NUM> is placed between the sheet battery 110a and the sheet battery 110b in the area where the base material <NUM> is exposed. By placing the insulating material <NUM> in this exposure position, it is possible to prevent the second electrode <NUM> from being short-circuited with the first electrode of the other sheet battery <NUM>.

Note that the sheet batteries <NUM> are also laminated in the same manner to form a sheet pair. The two sheet batteries <NUM> are placed with their second electrodes facing each other and being connected. <FIG> shows the X-Y plane shape of a sheet pair <NUM> that includes sheet batteries 210c and 210d. Note that the laminated construction of the sheet pair <NUM> is the same as that of the sheet pair <NUM> and therefore the description thereof is omitted.

In the sheet pair <NUM>, the type-II sheet batteries 210c and 210d shown in <FIG> are laminated together with the laminate 220c and the laminate 220d facing each other. To be specific, the laminate 220c of the sheet battery 210c faces upward, and the laminate 220d of the sheet battery 210d faces downward. Specifically, rotating the sheet battery <NUM> in <FIG> by <NUM>° about the Y axis being the axis of rotation gives the orientation of the sheet battery 210d. The sheet battery 210c and the sheet battery 210d are placed in such a way that their second electrodes <NUM> face each other and are connected.

In the sheet pair <NUM>, the positions of the tab parts 232c and 232d along the X direction are different. The tab part 232c is placed at the -X side edge, and the tab part 232d is placed at the +X side edge. The tab part 232c of the sheet battery 210c projects to the outer side of the sheet battery 210d on the X-Y plane. Likewise, the tab part 132d of the sheet battery 210d projects to the outer side of the sheet battery 210c on the X-Y plane.

As described above, two kinds of sheet pairs <NUM> and <NUM> are used in this embodiment. Note that, in a sheet pair composed of two sheet batteries of the same type, the positions of the tab parts are different on the X-Y plane where the sheet batteries are laminated. Specifically, in the sheet pair, the tab part of one sheet battery protrudes to the outside of the other sheet battery. The sheet pair <NUM> is referred to as a first sheet pair <NUM>, and the sheet pair <NUM> is referred to as a second sheet pair <NUM>.

When laminating the sheet pairs <NUM> and <NUM> together, the sheet batteries <NUM> and <NUM> are laminated in such a way that the rectangular parts <NUM> and <NUM> overlap each other. Thus, on the X-Y plane, the tab part 232c of the sheet pair <NUM> overlaps the tab part 132a of the sheet pair <NUM>, and the tab part 232d of the sheet pair <NUM> overlaps the tab part 132b of the sheet pair <NUM>. Note that the tab part 132a and the tab part 232c are placed with the laminates 120a and 220c facing the +Z side, and the tab part 132b and the tab part 232d are placed with the laminates 120b and 220d facing the -Z side.

The structure of a laminated battery having a plurality of sheet pairs is described hereinafter with reference to <FIG> and <FIG>. <FIG> is a schematic view showing the structure of a laminated battery <NUM>. <FIG> is an X-Z plane view showing the side structure of the laminated battery <NUM>. Note that, in the laminated battery <NUM>, the sheet batteries <NUM> and <NUM> are laminated with their substantially whole areas overlapping each other. In <FIG>, the sheet batteries <NUM> and <NUM> are partly displaced to clarify the description.

<FIG> and <FIG> show the laminated battery <NUM> that includes <NUM> sheet batteries 110a, 110b, 210c, 210d, 110e, 110f, <NUM>, and <NUM>. The sheet batteries 110a, 110b, 110e and 110f are the type-I sheet batteries <NUM> shown in <FIG>. The sheet batteries 210c, 210d, <NUM> and <NUM> are the type-II sheet batteries <NUM> show in <FIG>.

In <FIG> and <FIG>, tab parts placed in the sheet batteries 110a, 110b, 110e and 110f are tab parts 132a, 132b, 132e and 132f, respectively. Laminates placed in the sheet batteries 110a, 110b, 110e and 110f are laminates 120a, 120b, 120e and 120f, respectively. Likewise, tab parts placed in the sheet batteries 210c, 210d, <NUM> and <NUM> are tab parts 232c, 232d, <NUM> and <NUM>, respectively. Laminates placed in the sheet batteries 210c, 210d, <NUM> and <NUM> are laminates 220c, 220d, <NUM> and <NUM>, respectively. Further, in <FIG>, base materials placed in the sheet batteries 110a, 110b, 110e and 110f are base materials 111a, 111b, 111e and 111f, respectively, and base materials placed in the sheet batteries 210c, 210d, <NUM> and <NUM> are base materials 211c, 211d, <NUM> and <NUM>, respectively.

In the following description, when there is no particular need to distinguish among the sheet batteries 110a, 110b, 210c, 210d, 110e, 110f, <NUM>, and <NUM>, the alphabet "a" to "h" are omitted and they are simply referred to as the sheet batteries <NUM> and <NUM>, which is the same for the other elements.

As shown in <FIG>, the sheet batteries 110a, 110b, 210c, 210d, 110e, 110f, <NUM>, and <NUM> are laminated in this order. In <FIG>, the sheet battery 110a is placed on the lowermost side, and the sheet battery <NUM> is placed on the uppermost side. Note that the sheet batteries 110a, 110b, 210c, 210d, 110e, 110f, <NUM>, and <NUM> are sequentially referred to as a first sheet battery 110a to an eighth sheet battery <NUM>, which is the same for the other elements.

In <FIG> and <FIG>, sheet pairs composed of the type-I sheet batteries <NUM> are sheet pairs 150a and 150e. The first sheet pair 150a has two sheet batteries 110a and 110b. The sheet pair 150e has two sheet batteries 110e and 110f. Likewise, sheet pairs composed of the type-II sheet batteries <NUM> are sheet pairs 250c and <NUM>. The second sheet pair 250c has two sheet batteries 210c and 210d. The sheet pair <NUM> has two sheet batteries <NUM> and <NUM>.

In the sheet pair 150a, the laminate 120a and the laminate 120b are placed facing each other, and therefore the second electrodes <NUM> (not shown in <FIG> and <FIG>) are connected to each other as shown in <FIG>. Likewise, in the sheet pair 150e, the laminate 120e and the laminate 120f are placed facing each other, and therefore the second electrodes <NUM> (not shown in <FIG> and <FIG>) are connected to each other. In the sheet pair 250c, the laminate 220c and the laminate 220d are placed facing each other, and therefore the second electrodes <NUM> (not shown in <FIG> and <FIG>) are connected to each other. Likewise, in the sheet pair <NUM>, the laminate <NUM> and the laminate <NUM> are placed facing each other, and therefore the second electrodes <NUM> (not shown in <FIG> and <FIG>) are connected to each other. In this manner, the positive electrodes are connected to each other in each of the sheet pairs 150a, 150e, 250c and <NUM>.

As shown in <FIG>, the sheet batteries 110b, 210d, 110f and <NUM> are placed in such a way that the laminates 120b, 220d, 120f and <NUM> face downward. For example, in the second sheet battery 110b, the base material 111b is placed on the upper side of the laminate 120b. In the fourth sheet battery 210d also, the base material 211d is placed on the upper side of the laminate 220d. In the sixth sheet battery 110f also, the base material 111f is placed on the upper side of the laminate 120f. In the eighth sheet battery <NUM> also, the base material <NUM> is placed on the upper side of the laminate <NUM>.

On the other hand, as shown in <FIG>, the sheet batteries 110a, 210c, 110e and <NUM> are placed in such a way that the laminates 120a, 220c, 120e and <NUM> face upward. In the first sheet battery 110a, the base material 111a is placed on the lower side of the laminate 120a. In the third sheet battery 210c also, the base material 211c is placed on the lower side of the laminate 220c. In the fifth sheet battery 110e also, the base material 111e is placed on the lower side of the laminate 120e. In the seventh sheet battery <NUM> also, the base material <NUM> is placed on the lower side of the laminate <NUM>.

As shown in <FIG>, the orientations of the base material and the laminate are vertically inverted between the odd-numbered sheet batteries 110a, 210c, 110e and <NUM> and the even-numbered sheet batteries 110b, 210d, 110f and <NUM> in their laminated structures.

Therefore, the base material 111b of the second sheet battery 110b and the base material 211c of the third sheet battery 210c are placed face-to-face with each other and connected. Likewise, the base material 211d of the fourth sheet battery 210d and the base material 111e of the fifth sheet battery 110e are placed face-to-face with each other and connected. The base material 111f of the sixth sheet battery 110f and the base material <NUM> of the seventh sheet battery <NUM> are placed face-to-face with each other and connected.

The sheet batteries 110a, 110b, 110e and 110f are the type-I sheet batteries <NUM> shown in <FIG>, and the sheet batteries 210c, 210d, <NUM> and <NUM> are the type-II sheet batteries <NUM> show in <FIG>. The orientation of the laminate is different between the even-numbered sheet batteries and the odd-numbered sheet batteries.

Thus, the tab parts 132a, 232d, 132e and <NUM> of the first sheet battery 110a, the fourth sheet battery 210d, the fifth sheet battery 110e and the eighth sheet battery <NUM> are placed at the +X side edge. The tab parts 132a, 232d, 132e and <NUM> thereby overlap each other on the X-Y plane (refer also to <FIG>).

The tab parts 132b, 232c, 132f and <NUM> of the second sheet battery 110b, the third sheet battery 210c, the sixth sheet battery 110f and the seventh sheet battery <NUM> are placed at the -X side edge. The tab parts 132b, 232c, 132f and <NUM> thereby overlap each other on the X-Y plane (refer also to <FIG>). Further, the tab parts 132b, 232c, 132f and <NUM> and the tab parts 132a, 232d, 132e and <NUM> are arranged in a staggered fashion on the X-Y plane.

Because the first tab part 132a overlaps the fourth tab part 232d, the second electrode <NUM> of the first tab part 132a and the second electrode <NUM> of the fourth tab part 232d are placed face-to-face with each other. The second electrode <NUM> of the first tab part 132a and the second electrode <NUM> of the fourth tab part 232d can be thereby easily connected.

To be specific, the laminated battery <NUM> has a conductive bonding agent 45ad so as to connect the second electrode <NUM> of the first tab part 132a and the second electrode <NUM> of the fourth tab part 232d. Specifically, the first tab part 132a and the fourth tab part 232d are bonded together, and the second electrode <NUM> of the first sheet battery 110a and the second electrode <NUM> of the fourth sheet battery 210d are connected through the conductive bonding agent 45ad. The second electrodes <NUM> of the two adjacent sheet pairs 150a and 250c are thereby connected. Because the two sheet batteries 110b and 210c are placed between the first sheet battery 110a and the fourth sheet battery 210d, the conductive bonding agent 45ad corresponds to the thickness of the two sheet batteries.

Likewise, because the third tab part 232c overlaps the sixth tab part 132f, the second electrode <NUM> of the third tab part 232c and the second electrode <NUM> of the sixth tab part 132f are placed face-to-face with each other. The second electrode <NUM> of the third tab part 232c and the second electrode <NUM> of the sixth tab part 132f can be thereby easily connected.

To be specific, the laminated battery <NUM> has a conductive bonding agent 45cf so as to connect the second electrode <NUM> of the third tab part 232c and the second electrode <NUM> of the sixth tab part 132f. Specifically, the third tab part 232c and the sixth tab part 132f are bonded together, and the second electrode <NUM> of the third sheet battery 210c and the second electrode <NUM> of the sixth sheet battery 110f are connected through the conductive bonding agent 45cf. The second electrodes <NUM> of the two adjacent sheet pairs 150e and 250c are thereby connected. Because the two sheet batteries 210d and 110e are placed between the third sheet battery 210c and the sixth sheet battery 110f, the conductive bonding agent 45cf corresponds to the thickness of the two sheet batteries.

Further, because the fifth tab part 132e overlaps the eighth tab part <NUM>, the second electrode <NUM> of the fifth tab part 132e and the second electrode <NUM> of the eighth tab part <NUM> are placed face-to-face with each other. The second electrode <NUM> of the fifth tab part 132e and the second electrode <NUM> of the eighth tab part <NUM> can be thereby easily connected.

To be specific, the laminated battery <NUM> has a conductive bonding agent 45eh so as to connect the second electrode <NUM> of the fifth tab part 132e and the second electrode <NUM> of the eighth tab part <NUM>. Specifically, the fifth tab part 132e and the eighth tab part <NUM> are bonded together, and the second electrode <NUM> of the fifth sheet battery 110e and the second electrode <NUM> of the eighth sheet battery <NUM> are connected through the conductive bonding agent 45eh. The second electrodes <NUM> of the two adjacent sheet pairs 150e and <NUM> are thereby connected. Because the two sheet batteries 110f and <NUM> are placed between the fifth sheet battery 110e and the eighth sheet battery <NUM>, the conductive bonding agent 45eh corresponds to the thickness of the two sheet batteries.

As described above, use of the conductive bonding agents 45ad, 45cf and 45eh allows all the second electrodes <NUM> of the eight sheet batteries <NUM> and <NUM> to be connected in parallel. This eliminates the need for tab leads and comb-like electrodes for connecting the second electrodes <NUM>. It is thereby possible to reduce the number of parts and simplify the structure and the fabrication process. The productivity of the laminated battery is thereby improved. Each of the conductive bonding agents 45ad, 45cf and 45eh has a thickness corresponding to two sheets batteries, which reduces the thickness of the laminated battery. It is thereby possible to save the space.

The thickness of the bonding agent <NUM> is substantially equal to the total thickness of two sheets batteries. It is thereby possible to reduce a difference in thickness even when the number of laminated sheet batteries <NUM> and <NUM> is large. Easier lamination is achieved by making the thickness of a sheet pair equal to the thickness of a conductive bonding agent.

Further, because a lamination method is simple, it is possible to reduce manufacturing costs without adding an extra step. It is thereby possible to achieve a thinner laminated battery easily. Furthermore, because a plurality of sheet batteries <NUM> are connected in parallel, it is possible to achieve high-capacity.

Note that, although the laminated battery <NUM> that includes four sheet batteries <NUM> and four sheet batteries <NUM> is described in this embodiment, the total number of sheet batteries <NUM> and <NUM> included in the laminated battery <NUM> is not limited to <NUM>. The laminated battery <NUM> includes at least one sheet pair <NUM> and one sheet pair <NUM>. In other words, the laminated battery <NUM> includes four or more sheet batteries <NUM> and <NUM>.

Further, the laminated battery <NUM> preferably includes a plurality of sets of the sheet pair <NUM> and the sheet pair <NUM>, i.e., four sheet batteries <NUM> and <NUM>. For example, the total number of sheet batteries <NUM> and <NUM> included in the laminated battery <NUM> may be <NUM> or <NUM>. In this case, the sheet batteries <NUM> and <NUM> are laminated in such a way that the sheet pair <NUM> and the sheet pair <NUM> are arranged alternately.

Further, the laminated battery <NUM> may be folded. A structure of folding the laminated battery <NUM> is described hereinafter with reference to <FIG> is a plan view illustrating, in a simple way, the structure of the laminated battery <NUM> where a plurality of sheet batteries <NUM> and <NUM> are laminated.

As shown in <FIG>, the laminated battery <NUM> can be folded along a fold line X1 in parallel with the X direction. Folding the laminated battery <NUM> allows the area on the X-Y plane to be reduced half, thereby easily reducing the size of the laminated battery <NUM>. The fold line X1 does not lie across the tab parts <NUM> and <NUM>. Only the rectangular parts <NUM> and <NUM> are thereby folded. Thus, the laminated battery <NUM> is folded without folding the tab parts <NUM> and <NUM>.

Further, areas of the tab parts <NUM> and <NUM> which are on the +Y side of the laminate <NUM> are joint regions <NUM> and <NUM>. The joint regions <NUM> and <NUM> are peripheral areas of the base materials <NUM> band <NUM>, respectively. In the peripheral areas of the base materials <NUM> band <NUM>, the laminate <NUM> is not placed, and the base materials <NUM> band <NUM> are exposed. Specifically, in the joint regions <NUM> and <NUM>, the base materials <NUM> band <NUM> are exposed on the surfaces of the both sheet batteries <NUM> and <NUM>. A joint part <NUM> joins the joint regions <NUM> and <NUM> together. In this manner, in the joint part <NUM>, the peripheral areas of the base materials <NUM> and <NUM> of the sheet battery <NUM> and the sheet battery <NUM> are joined together.

The joint part <NUM> is formed by welding such as resistance welding or ultrasonic welding, for example. The first electrodes of all the sheet batteries <NUM> and <NUM> are thereby connected. The plurality of sheet batteries <NUM> and <NUM> can be thereby connected in parallel. Further, all the sheet batteries <NUM> and <NUM> are bonded together in the joint part <NUM>. Thus easily reduces the size of the laminated battery <NUM>.

This embodiment is the same as the first embodiment in that sheet batteries are laminated, and is different from the first embodiment in the planar shape of sheet batteries. The planar shape of a sheet battery <NUM> according to this embodiment is described hereinafter with reference to <FIG>. Note that, in this embodiment, all of sheet batteries <NUM> have the same planar shape. Specifically, all of sheet batteries are the type III. Note that the description common to the first embodiment is omitted as appropriate below.

The type-III sheet battery <NUM> is different from the type-I sheet battery <NUM> and the type-II sheet battery <NUM> in the positions of a tab part <NUM> and an insulating material <NUM>. Note that the type-III sheet battery <NUM> is the same as the sheet batteries <NUM> and <NUM> of the first embodiment except for the position of the tab part <NUM>, and the description thereof is omitted. For example, a base material <NUM> and a laminate <NUM> are the same as the base material <NUM> and the laminate <NUM>, respectively, and the description thereof is omitted.

A rectangular part <NUM> is oblong or square on the X-Y plane. The tab part <NUM> projects in the +Y direction from the rectangular part <NUM>. The tab part <NUM> is placed in the middle of the rectangular part <NUM> in the X direction.

The insulating material <NUM> is placed at the -Y side edge of the rectangular part <NUM>. The insulating material <NUM> is placed in the middle of the rectangular part <NUM> in the X direction. Thus, the positions of the tab part <NUM> and the insulating material <NUM> in the X direction coincide with each other.

A battery structure where two sheet batteries <NUM> are laminated together is described hereinafter with reference to <FIG>. Hereinafter, the battery structure where two sheet batteries 310a and 310b are laminated together is described as a sheet pair 350a. <FIG> is an exploded perspective view of the sheet pair 350a. <FIG> is an X-Z plane view showing the side structure of the sheet pair 350a. <FIG> is an X-Y plane view showing the planar structure of the sheet pair 350a.

The sheet battery 310a and the sheet battery 310b are placed with the second electrodes 17a and 17b facing each other. Thus, the sheet battery 310b has a structure that is the inverse of the sheet battery <NUM> in <FIG>. To be specific, rotating the sheet battery <NUM> in <FIG> about the X axis being the axis of rotation gives the orientation of the sheet battery 310b. The sheet battery 310a is in the same orientation as the sheet battery <NUM> in <FIG>.

The second electrode 17a of the sheet battery 310a is placed facing upward, and the second electrode 17b of the sheet battery 310b is placed facing downward. Thus, as shown in <FIG>, the laminate 320a is placed on the upper side of the base material 311a in the sheet battery 310a, and the laminate 320b is placed on the lower side of the base material 311b in the sheet battery 310b. The sheet battery 310a and the sheet battery 310b are laminated together in such a way that the rectangular part 331a and the rectangular part 331b overlap each other when the XY plane is viewed from above.

In the sheet pair 350a, the second electrode 17a of the sheet battery 310a and the second electrode 17b of the sheet battery 310b are placed face-to-face with each other and connected. The second electrode 17a is exposed on the upper surface of the sheet battery 310a, and the second electrode 17b is exposed on the lower surface of the sheet battery 310b. The second electrode 17a of the sheet battery 310a and the second electrode 17b of the sheet battery 310b thereby become electrically continuous.

Further, a tab part 332a and a tab part 332b are placed in different positions on the X-Y plane. To be specific, the tab part 332a is placed at the +Y side edge, and the tab part 332b is placed at the -Y side edge. Therefore, just like in the first embodiment, the tab part 332a protrudes to the outside of the sheet battery 310b on the X-Y plane. The tab part 332b protrudes to the outside of the sheet battery 310a on the X-Y plane.

An insulating material 343b is placed in close proximity to the tab part 332a. Thus, the insulating material 343b is thereby interposed between the base material 311b and the second electrode 17a of the sheet battery 310a. This prevents short-circuit between the base material 311b and the second electrode 17a of the sheet battery 310a. Likewise, an insulating material 343a is interposed between the base material 311a and the second electrode 17b of the sheet battery 310b, which prevents short-circuit.

The structure of a sheet pair 350c having a different planar structure from the sheet pair 350a is described hereinafter with reference to <FIG>. The sheet pair 350c includes a sheet battery 310c and a sheet battery 310d.

The sheet battery 310c and the sheet battery 310d are placed with second electrodes 17c and 17d facing each other. The second electrode 17c of the sheet battery 310c is placed facing upward, and the second electrode 17d of the sheet battery 310d is placed facing downward. Thus, rotating the planar shape of <FIG> by <NUM>° about the Z axis being the axis of rotation gives the planar shape shown in <FIG>. In this case, the sheet battery 310a corresponds to the sheet battery 310c, and the sheet battery 310b corresponds to the sheet battery 310d.

A tab part 332c and a tab part 332d are placed in different positions on the X-Y plane. To be specific, the tab part 332d is placed at the +Y side edge, and the tab part 332c is placed at the -Y side edge. Therefore, just like in the first embodiment, the tab part 332c protrudes to the outside of the sheet battery 310d on the X-Y plane, and the tab part 332d protrudes to the outside of the sheet battery 310c on the X-Y plane.

When laminating the sheet pair 350a and the sheet pair 350c together, they are laminated in such a way that the tab part 332a of the sheet battery 310a and the tab part 332d of the sheet battery 310d overlap each other on the X-Y plane. Likewise, the tab part 332b of the sheet battery 310b and the tab part 332c of the sheet battery 310c overlap each other on the X-Y plane. The tab part 332a and the tab part 332d are arranged in a staggered fashion on the X-Y plane.

The structure of a laminated battery <NUM> where a plurality of sheet batteries <NUM> are laminated is described hereinafter with reference to <FIG> is an X-Z plane view showing the laminated structure of the laminated battery <NUM>.

The laminated battery <NUM> includes <NUM> sheet battery 310a to sheet battery <NUM>. As shown in <FIG>, a sheet battery 310a, a sheet battery 310b, a sheet battery 310c, a sheet battery 310d, a sheet battery 310e, a sheet battery 310f, a sheet battery <NUM>, and a sheet battery <NUM> are laminated in this order from the bottom.

A sheet pair 350a includes the sheet battery 310a and the sheet battery 310b, having the planar shape shown in <FIG>. A sheet pair 350c includes the sheet battery 310c and the sheet battery 310d, having the planar shape shown in <FIG>.

A sheet pair 350e includes the sheet battery 310e and the sheet battery 310f, having the planar shape shown in <FIG>. Thus, the sheet battery 310e has the same planar shape as the sheet battery 310a, and the sheet battery 310f has the same planar shape as the sheet battery 310d.

A sheet pair <NUM> includes the sheet battery <NUM> and the sheet battery <NUM>, having the planar shape shown in <FIG>. Thus, the sheet battery <NUM> has the same planar shape as the sheet battery 310c, and the sheet battery <NUM> has the same planar shape as the sheet battery 310f.

Thus, the second electrodes are connected to each other in the tab parts, just like in the first embodiment. For example, in the tab parts 332a and 332d, the second electrode <NUM> (not shown in <FIG>) of the sheet battery 310a and the second electrode <NUM> (not shown in <FIG>) of the sheet battery 310d are connected through a conductive bonding agent 345ad. Further, in the tab parts 332e and <NUM>, the second electrode <NUM> (not shown in <FIG>) of the sheet battery 310e and the second electrode <NUM> (not shown in <FIG>) of the sheet battery <NUM> are connected through a conductive bonding agent 345eh. Note that, although not shown in <FIG>, in the tab parts 332c and 332f, the second electrode <NUM> (not shown in <FIG>) of the sheet battery 310c and the second electrode <NUM> (not shown in <FIG>) of the sheet battery 310f are connected through a conductive bonding agent.

In this manner, the same effects as in the first embodiment are obtained. For example, because the need for tab leads and comb-like electrodes is eliminated, it is possible to reduce the number of parts and simplify the structure and the fabrication process. Further, it is possible to reduce the thickness of the laminated battery <NUM>, just like in the first embodiment. Because one type of the sheet battery <NUM> is used in this embodiment, it is possible to further reduce the number of parts.

The laminated battery <NUM> having such a structure can be also folded like the laminated battery <NUM> of the first embodiment. For example, as shown in <FIG>, the laminated battery <NUM> can be folded along fold lines Y1 and Y2 in parallel with the Y direction. The laminated battery <NUM> is thereby reduced in size. The fold lines Y1 and Y2 do not lie across the tab part <NUM>. Thus, only the rectangular part <NUM> is folded.

As shown in <FIG>, an area of the tab part <NUM> which is on the outer side of the laminate <NUM> is a joint region <NUM>. In the joint region <NUM>, the laminate <NUM> is not placed and therefore the base material <NUM> is exposed. Thus, in the joint region <NUM>, the base material <NUM> is exposed on both surfaces of the sheet battery <NUM>. A joint part <NUM> joins the joint region <NUM>.

The joint part <NUM> is formed by welding such as resistance welding or ultrasonic welding, for example. The first electrodes of all the sheet batteries <NUM> are thereby connected. The plurality of sheet batteries <NUM> can be thereby connected in parallel. Further, all the sheet batteries <NUM> are bonded together in the joint part <NUM>. Thus easily reduces the size of the laminated battery <NUM>.

The cross-sectional structure of a sheet battery that is used in this embodiment is described hereinafter with reference to <FIG> is a cross-sectional view showing the laminated structure of a sheet battery <NUM>. A laminate <NUM> is placed on one surface of a base material <NUM>, and a laminate <NUM> is placed on the other surface of the base material <NUM>. Note that the description common to the first and second embodiments is omitted as appropriate below.

The laminated structure of the laminate <NUM> and the laminate <NUM> is the same as the laminate <NUM> described in the first embodiment. Specifically, the n-type oxide semiconductor layer <NUM>, the charging layer <NUM>, the p-type oxide semiconductor layer <NUM>, and the second electrode <NUM> of the laminate <NUM> correspond to an n-type oxide semiconductor layer <NUM>, a charging layer <NUM>, a p-type oxide semiconductor layer <NUM>, and a second electrode <NUM> of the laminate <NUM>, respectively. Likewise, the n-type oxide semiconductor layer <NUM>, the charging layer <NUM>, the p-type oxide semiconductor layer <NUM>, and the second electrode <NUM> of the laminate <NUM> correspond to an n-type oxide semiconductor layer <NUM>, a charging layer <NUM>, a p-type oxide semiconductor layer <NUM>, and a second electrode <NUM> of the laminate <NUM>, respectively.

Therefore, a second electrode <NUM> is placed on one surface of the base material <NUM>, and a second electrode <NUM> is placed on the other surface of the base material <NUM>.

In this embodiment, two types of sheet batteries are used. To be specific, the two types of sheet batteries are the sheet battery <NUM> where the laminate is placed on both surfaces of the base material <NUM> as shown in <FIG> and the sheet battery <NUM> where the laminate <NUM> is placed only on one surface of the base material <NUM> as shown in <FIG>.

<FIG> shows the planar shapes of two types of sheet batteries. The sheet battery <NUM> where the laminate is placed on both surfaces is referred to as a type-IV sheet battery <NUM>, and the sheet battery <NUM> where the laminate <NUM> is placed only on one surface is referred to as a type-V sheet battery <NUM>. Note that the sheet battery <NUM> is also called a double-sided battery sheet, and the sheet battery <NUM> is also called a single-sided battery sheet.

In the sheet battery <NUM>, a laminate <NUM> is formed on one surface of a base material <NUM>. Note that the laminate formed on the other surface of the base material <NUM> is a laminate <NUM>. The laminate <NUM> corresponds to the laminate <NUM> in <FIG>. The laminate <NUM> corresponds to the laminate <NUM> in <FIG>. The shape, size and position of the laminate <NUM> and the laminate <NUM> are the same on the X-Y plane.

In the sheet battery <NUM>, a laminate <NUM> is formed on a base material <NUM>. The size and shape of the laminate <NUM> are the same as those of the laminates <NUM> and <NUM>.

The sheet battery <NUM> includes a rectangular part <NUM> and a tab part <NUM>. The sheet battery <NUM> includes a rectangular part <NUM> and a tab part <NUM>. The sheet battery <NUM> has an insulating material <NUM> for preventing short-circuit between the first electrode and the second electrode. The insulating material <NUM> may be placed on both surfaces or only on one surface of the base material <NUM>. The sheet battery <NUM> has an insulating material <NUM> for preventing short-circuit between the first electrode and the second electrode. The shape, position and structure of the insulating materials <NUM> and <NUM> are the same as those of the insulating material <NUM> and therefore the description thereof is omitted.

The base material <NUM> of the sheet battery <NUM> and the base material <NUM> of the sheet battery <NUM> have the same shape as the base material <NUM> of the type-I sheet battery <NUM>. The tab parts <NUM> and <NUM> are located in the same position as the tab part <NUM>.

A battery structure where two sheet batteries <NUM> are laminated together is described hereinafter with reference to <FIG> and <FIG>. Hereinafter, the battery structure where two sheet batteries <NUM> are laminated together is described as a sheet pair <NUM>. <FIG> is an X-Z plane view showing the side structure of the sheet pair <NUM>. <FIG> is an X-Y plane view showing the planar shape of the sheet pair <NUM>.

The sheet pair <NUM> has a sheet battery 660b and a sheet battery 660c. The sheet battery 660c and the sheet battery 660b are type-IV sheet batteries <NUM> shown in <FIG>. In the sheet pair <NUM>, the two sheet battery 660c and sheet battery 660b overlap each other in the same orientation.

The sheet battery 660c and the sheet battery 660b are arranged completely overlapping each other. A tab part 632c of the sheet battery 660c and a tab part 632b of the sheet battery 660b are the same position in the X direction, which is different from the first and second embodiments. Thus, the tab part 632c of the sheet battery 660c and the tab part 632b of the sheet battery 660b overlap each other on the X-Y plane. A second electrode 67c of the sheet battery 660c and a second electrode 87b of the sheet battery 660b are connected face-to-face with each other.

The structure of a laminated battery <NUM> where a plurality of sheet batteries <NUM> and <NUM> are laminated is described hereinafter with reference to <FIG> is a view schematically showing the structure of the laminated battery <NUM>.

The laminated battery <NUM> includes a sheet battery 710a, a sheet pair 650b, a sheet pair 650d, a sheet pair 650f, a sheet pair <NUM>, and a sheet battery 710j. The sheet battery 710a, the sheet pair 650b, the sheet pair 650d, the sheet pair 650f, the sheet pair <NUM>, and the sheet battery 710j are laminated in this order.

The sheet batteries 710a and 710j are the type-V sheet batteries <NUM> shown in <FIG>. The sheet pairs 650b, 650d, 650f and <NUM> are the sheet pairs <NUM> shown in <FIG> and <FIG>. The sheet pair <NUM> has two sheet batteries <NUM>. Thus, the laminated battery <NUM> includes two sheet batteries <NUM> and eight sheet batteries <NUM>.

Note that the two sheet batteries <NUM> that constitute the sheet pair 650b are sheet batteries 660b and 660c as shown in <FIG> and <FIG>. Further, the two sheet batteries <NUM> that constitute the sheet pair 650d are sheet batteries 660d and 660e. The two sheet batteries <NUM> that constitute the sheet pair 650f are sheet batteries 660f and <NUM>. The two sheet batteries <NUM> that constitute the sheet pair <NUM> are sheet batteries <NUM> and 660i.

The sheet battery 710a has the same structure as shown in <FIG>. The sheet battery 710j has a structure that is the inverse of the structure shown in <FIG>. The sheet pairs 650d and <NUM> have the same structure as shown in <FIG> and <FIG>. The sheet pairs 650b and 650f have a structure that is the inverse of the structure shown in <FIG> and <FIG>.

Thus, in the sheet battery 710j and the sheet pairs 650b and 650f, tab parts 732j and <NUM> are placed at the -X side edge. The tab parts 732j and <NUM> of the sheet battery 710j and the sheet pairs 650b and 650f overlap each other on the X-Y plane. In the sheet battery 710a and the sheet pairs 650d and <NUM>, tab parts 732a and <NUM> are placed at the -X side edge. The tab parts 732a and <NUM> of the sheet battery 710a and the sheet pairs 650d and <NUM> overlap each other on the X-Y plane.

As described in the first and second embodiments, the second electrodes can be connected by using the conductive bonding agent having a thickness corresponding to the total thickness of two sheet batteries (not shown in <FIG>). For example, in the tab part at the +X side edge, the second electrode <NUM> of the sheet battery 710a and the second electrode <NUM> of the sheet pair 650d are placed face-to-face with each other and connected.

Likewise, in the tab part at the +X side edge, the second electrode <NUM> of the sheet pair 650d and the second electrode <NUM> of the sheet pair <NUM> are placed face-to-face with each other and connected. Further, in the tab part at the -X side edge, the second electrode <NUM> of the sheet pair 650b and the second electrode <NUM> of the sheet pair 650f are placed face-to-face with each other and connected. Likewise, in the tab part at the -X side edge, the second electrode <NUM> of the sheet battery 710j and the second electrode <NUM> of the sheet pair 650f are placed face-to-face with each other and connected. A conductive bonding agent is used for connection of the second electrodes <NUM> in the tag parts as described in the first and second embodiments.

In this manner, the same effects as in the first and second embodiments are obtained. Further, an insulating material is not needed in this embodiment, which allows further reduction of the number of parts. It is thereby possible to further improve productivity. In addition, because a double-sided battery sheet is used, it is possible to further increase the battery capacity.

The laminated battery <NUM> may be folded as described in the first embodiment. Further, the peripheral areas of the sheet batteries <NUM> and <NUM> may serve as joint regions and joined together by welding or the like.

In the third embodiment, the uppermost and lower most sheet batteries of the laminated battery <NUM> in the thickness direction may be single-sided battery sheets, and sheet batteries between them may be double-sided battery sheets. Further, the number of sheet batteries included in the laminated battery <NUM> is four or more. The laminated battery <NUM> at least includes two sheet batteries <NUM> and two sheet batteries <NUM>.

In the first and second embodiments, a position to form an insulating material is not limited to the proximity to a tab part. For example, an insulating material may be formed on the entire periphery of a base material. <FIG> and <FIG> show an example where an insulating material is formed on the entire periphery of a base material.

As shown in <FIG> and <FIG>, insulating materials 143a and 143b may be formed on the entire periphery of the sheet batteries 110a and 110b, respectively. Specifically, the insulating material 143a is formed continuously on the entire periphery of the sheet battery 110a and surrounds the laminate 120a when the XY plane is viewed from above. In the peripheral part of the base material 111a, the insulating material 143a is on the uppermost surface, and in the central part, the laminate 120a is on the uppermost surface. In this structure also, the insulating material 143a is interposed between the laminate 120a in the tab part 132a and the base material 111b. This prevents short-circuit between electrodes. Further, the insulating material 143b is interposed between the laminate 120b in the tab part 132b and the base material 111a. This prevents short-circuit between electrodes.

In this embodiment, the insulating material <NUM> is formed on the entire periphery of the sheet battery <NUM>. This more reliably prevents short-circuit. Note that the structure of the insulating material <NUM> is not limited to the above-described structure. The insulating material <NUM> may have the minimum necessary structure as shown in the first and second embodiments or may be formed continuously on the entire periphery as shown in <FIG> and <FIG>, as long as it can prevent short-circuit between electrodes. The insulating material <NUM> may have another structure as a matter of course. Further, the insulating material <NUM> may be placed on the entire periphery of the sheet battery <NUM> in some part of the laminated battery, and the insulating material <NUM> may be placed only on a part of the periphery of the sheet battery <NUM> in another part of the laminated battery. The insulating material on the entire periphery as shown in <FIG> and <FIG> may be used also in the second and third embodiments.

In the sheet battery, a position to place the tab part is not limited to the above-described position. In the first and second embodiments, the tab parts are placed at positions not overlapping each other. In the third embodiment, the tab parts are placed at positions overlapping each other in the sheet pair.

Claim 1:
A secondary battery (<NUM>) in which a plurality of sheet batteries (<NUM>) are laminated, comprising:
a first sheet battery (110a), a second sheet battery (110b), a third sheet battery (210c) and a fourth sheet battery (210d), each including a first electrode (<NUM>) on a front side surface and a second electrode (<NUM>) on a back side surface, wherein
when viewed from above in a state where the first sheet battery (110a), the second sheet battery (110b), the third sheet battery (210c) and the fourth sheet battery (210d) are laminated,
the first sheet battery (110a) includes a first tab part (132a) placed so as to project outward of the second sheet battery (110b), and the second sheet battery (110b) includes a second tab part (132b) placed so as to project outward of the first sheet battery (110a) in a state where the second electrode (17a) of the first sheet battery (110a) and the second electrode (17b) of the second sheet battery (110b) are placed face-to-face to each other,
the third sheet battery (210c) includes a third tab part (232c) placed so as to project outward of the fourth sheet battery (210d), and the fourth sheet battery (210d) includes a fourth tab part (232d) placed so as to project outward of the third sheet battery (210c) in a state where the second electrode (17c) of the third sheet battery (210c) and the second electrode (17d) of the fourth sheet battery (210d) are placed face-to-face to each other,
the first tab part (132a) and the fourth tab part (232d) overlap each other so that the second electrode (17a) on the surface of the first tab part (132a) and the second electrode (17d) on the surface of the fourth tab part (232d) are placed face-to-face to each other;
and
the second tab part and the third tab part are placed so as to overlap each other when viewed from above in a state where the first to fourth sheet batteries are laminated.