JP2011070977A - Laminated battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated battery capable of improving volume energy density by folding down a sealing section of an outer package made from a laminated film. <P>SOLUTION: The laminated battery includes the outer package 19 made from the laminated film, a battery element 9 sealed with the sealing section 19b of the outer package 19, and a positive electrode tab terminal and a negative electrode tab terminal which are electrically and internally connected to the battery element 9 and are stuck out from the outer package 19 to the outside. In the battery element 9, ends 4a, 4a, ... of a positive electrode collector and ends 4b, 4b, ... of the negative electrode collector are arranged along two sides of the outer package 19 which are faced each other, and the sealing section 19b, 19b of the outer package 19 are folded down so as to be respectively overlapped on the ends 4a, 4a, ... of the positive electrode collector and the ends 4b, 4b, ... of the negative electrode collector. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laminate battery sealed with an exterior body made of a laminate film, and more particularly to a laminate battery in which the structure of the fused portion of the exterior body is improved.

  A secondary battery such as a lithium ion secondary battery using a laminate film as an outer package is an outer package made of a laminate film. The battery element has a laminate structure in which a positive electrode and a negative electrode with a separator interposed therebetween are stacked in layers. It is enclosed in a package formed by In response to recent demands for downsizing and thinning of electronic devices, the peripheral portions of the outer package that are heat-sealed to each other are often bent in order to reduce the volume of the secondary battery as much as possible.

  Patent Document 1 discloses a battery in which an end portion of an exterior body made of a laminate film is bent along the thickness of a battery cell (battery element).

JP 2001-250515 A

  In the battery disclosed in Patent Document 1, by folding the end portion of the exterior body made of a laminate film along the width direction of the battery, the dimension in the width direction necessary to accommodate the battery is reduced compared to the state where the battery is not bent. Can be small. However, since the dimension in the thickness direction is increased by the thickness of the bent portion, there is a problem that the volume energy density as the secondary battery cannot be greatly improved.

  This invention is made | formed in view of such a situation, and it aims at providing the laminated battery which can improve a volume energy density by bending the sealing part of the exterior body which consists of laminate films. .

  In order to achieve the above object, a laminated battery according to the first invention includes an exterior body made of a laminate film, a battery element sealed by a sealing portion of the exterior body, and the battery element and the interior electrically. In a substantially rectangular laminated battery having a positive electrode tab terminal and a negative electrode tab terminal that are connected and projecting outward from the exterior body, the battery element includes end portions of the positive electrode current collector and the negative electrode current collector, It is provided along two opposite sides of the exterior body, and the sealing part of the exterior body is bent so as to overlap the end portions of the positive electrode current collector and the negative electrode current collector, respectively. And

  In the first invention, the exterior body made of a laminate film, the battery element sealed by the sealing portion of the exterior body, and the battery element are electrically connected inside, and project from the exterior body to the outside. A positive electrode tab terminal and a negative electrode tab terminal. The ends of the positive electrode current collector and the negative electrode current collector of the battery element are provided along two opposing sides of the outer package, and the sealing portions of the outer package are connected to the ends of the positive electrode current collector and the negative electrode current collector. It is bent to overlap each other. Thus, even when the thickness of the sealed portion of the folded outer package and the thickness of the end of the positive electrode current collector or the negative electrode current collector are combined, it is equal to or less than the maximum thickness of the battery element and accommodates the battery. In addition, the dimension in the width direction necessary for this can be reduced, and the dimension in the thickness direction is not increased by the thickness of the bent portion, so that the volume energy density of the secondary battery can be improved.

  Moreover, in the laminated battery according to the second invention, in the first invention, the positive electrode tab terminal and the negative electrode tab terminal protrude substantially parallel from the same side different from the two opposite sides of the outer package. It is characterized by.

  In the second invention, the positive electrode tab terminal and the negative electrode tab terminal protrude substantially parallel from the same side different from the two opposite sides of the exterior body. This eliminates the need to bend the positive electrode tab terminal and the negative electrode tab terminal when the sealing portion is bent, and allows the sealing portion to be bent more closely to the ends of the positive electrode current collector and the negative electrode current collector. The dimension in the width direction necessary for housing the battery can be further reduced.

  Further, in the laminated battery according to the third invention, in the first or second invention, the end portion of the sealing portion includes an end portion of the positive electrode current collector and the negative electrode current collector, and the positive electrode current collector and The sealing portion of the outer package is bent to the battery element side so as to reach the vicinity of the boundary between the positive electrode mixture and the negative electrode mixture formed on the negative electrode current collector.

  In 3rd invention, the edge part of the sealing part has the edge part of a positive electrode electrical power collector and a negative electrode current collector, and the positive electrode mixture and negative electrode mixture currently formed on the positive electrode current collector and the negative electrode current collector, The thickness of the end of the positive electrode current collector or the negative electrode current collector is determined by folding the sealed portion of the outer package toward the battery element side so as to reach the vicinity of the boundary portion of the battery. And the maximum thickness of the battery element can be superimposed on the stepped portion, the width direction dimension required to accommodate the battery can be reduced, and the thickness direction depends on the thickness of the folded portion Therefore, the volume energy density of the secondary battery can be improved.

  With the above configuration, the thickness of the sealed portion of the outer package and the positive electrode current collector or the negative electrode are folded by folding the sealed portion of the outer package so as to overlap the end portions of the positive electrode current collector and the negative electrode current collector, respectively. Even when combined with the thickness of the end of the current collector, it is equal to or less than the maximum thickness of the battery element, and the width dimension required to accommodate the battery can be reduced, and the folded portion The dimension in the thickness direction is not increased by the thickness, and the volume energy density as the secondary battery can be improved.

It is a top view which shows typically the structure of the lithium ion secondary battery which concerns on embodiment of this invention. It is sectional drawing in the II-II line | wire of FIG. 1 which shows typically the structure of the battery element of the lithium ion secondary battery which concerns on embodiment of this invention. It is a top view which shows typically the structure of the battery element of the lithium ion secondary battery which concerns on embodiment of this invention. It is a fragmentary sectional view which shows the structure of the exterior body of the lithium ion secondary battery which concerns on embodiment of this invention. It is a fragmentary sectional view which shows the state which bent the sealing part of the exterior body of the lithium ion secondary battery which concerns on embodiment of this invention. It is a fragmentary top view in the case of bending the sealing part of the exterior body of the conventional lithium ion secondary battery. It is a fragmentary top view in the case of bending the sealing part of the exterior body of the lithium ion secondary battery which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a laminate type lithium ion secondary battery will be described as a laminate battery. However, battery elements include a lithium secondary battery, a polymer secondary battery, an organic radical battery, an all-solid battery, an electric battery A double layer capacitor or the like may be used and is not particularly limited thereto.

  FIG. 1 is a plan view schematically showing a configuration of a lithium ion secondary battery according to an embodiment of the present invention. As shown in FIG. 1, the lithium ion secondary battery 1 according to the present embodiment has a battery element 9 sandwiched between substantially the center of an exterior body 19 made of two flexible laminate films, The battery element 9 is sealed by heat-sealing the sealing portion 19b at the periphery of the body 19. In addition, the exterior body 19 may be obtained by superimposing two laminated films and heat-sealing the four sealing portions 19b, or by folding the single laminated film in two to form the three-side sealing portions 19b. It may be heat-sealed.

  The lithium ion secondary battery 1 according to the embodiment of the present invention has a substantially rectangular shape, and the positive electrode tab terminal 11a and the negative electrode tab terminal 11b that are connected to an external terminal for charging and discharging are both ends on the same side of the exterior body 19. It is arranged in the vicinity. In addition, in FIG. 1, the exterior body 19 is substantially square, but is not particularly limited, and may be substantially rectangular or substantially polygonal. In the case of a substantially rectangular shape, the one side on which the positive electrode tab terminal 11a is arranged may be a long side or a short side. Moreover, when it is a substantially polygon, it is preferable that the corner | angular part is chamfered.

  FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, schematically showing the configuration of the battery element 9 of the lithium ion secondary battery 1 according to the embodiment of the present invention. As shown in FIG. 2, the battery element 9 of the lithium ion secondary battery 1 according to the embodiment of the present invention includes a positive electrode plate 21 in which positive electrode mixtures 212 and 212 are laminated on a positive electrode current collector 211, a negative electrode A negative electrode plate 22 in which negative electrode mixtures 222 and 222 are laminated on a current collector 221 and a separator 23 interposed therebetween are provided. In addition, although not shown in figure, the electrolyte solution is inject | poured inside the exterior body 19, and the positive electrode plate 21, the negative electrode plate 22, and the separator 23 are immersed.

  The positive electrode plate 21 or the negative electrode plate 22 is formed by laminating the positive electrode active material or the negative electrode active material as the positive electrode mixture 212 or the negative electrode mixture 222 on both surfaces or one surface of the positive electrode current collector 211 or the negative electrode current collector 221, respectively. Is. For the positive electrode current collector 211 used for the positive electrode plate 21, a metal foil such as aluminum, stainless steel, or nickel can be used, and aluminum is particularly preferable. Moreover, metal foil, such as copper, stainless steel, nickel, can be used for the negative electrode collector 221 used for the negative electrode plate 22, and copper is particularly preferable.

Examples of the positive electrode active material used for the positive electrode mixture 212 include lithium cobaltate composite oxide (LCO), lithium manganate composite oxide (LMO), lithium nickelate composite oxide (LNO), and lithium-nickel-manganese-cobalt composite. An oxide (LNMCO), a lithium-manganese-nickel composite oxide (LMNO), a lithium-manganese-cobalt composite oxide (LMCO), a lithium-nickel-cobalt composite oxide (LNCO), or the like can be used. The positive electrode active material may be a mixture of the above materials. The positive electrode active material may be an olivine-based material such as LiFePO ₄ . As the negative electrode active material used for the negative electrode mixture 222, carbon materials such as graphite, hard carbon, and soft carbon, ceramics such as lithium titanate, and alloy materials such as Si and Sn can be used. The negative electrode active material may be a mixture of the above materials.

  The separator 23 is not particularly limited as long as it is a known material such as a polyolefin resin. In the present invention, the separator is not limited by its name, and instead of the separator, a solid electrolyte having a function (role) as a separator, a gel electrolyte, or the like may be used. A separator containing an inorganic material such as alumina or zirconia may also be used.

  As the electrolytic solution, cyclic carbonates such as ethylene carbonate (EC) and propylene carbonate (PC), and chain carbonates such as diethyl carbonate (DEC) and dimethyl carbonate (DMC) may be used alone or in combination of two or more. it can. Furthermore, chain ester systems such as methyl formate, ethyl formate, methyl acetate, and ethyl acetate, cyclic ester systems such as γ-butyrolactone, and cyclic sulfones such as sulfolane may be included.

  FIG. 3 is a plan view schematically showing the configuration of the battery element 9 of the lithium ion secondary battery 1 according to the embodiment of the present invention. As shown in FIG. 2, the battery element 9 is formed by alternately laminating a plurality of positive plates 21 and negative plates 22 with separators 23 interposed therebetween. Ends of the positive electrode current collector of each of the positive electrode plate 21 and the negative electrode plate 22 (hereinafter referred to as a non-coated portion of the positive electrode current collector, that is, a portion where the positive electrode mixture is not applied in the positive electrode current collector) 4a, The end portions of the negative electrode current collector (hereinafter referred to as the non-coated portion of the negative electrode current collector, that is, the portion where the negative electrode mixture is not applied in the negative electrode current collector) 4b are respectively different end sides of the battery element 9 That is, in the four sides of the exterior body 19 shown in FIG. 1, the positive electrode tab terminal 11a and the negative electrode tab terminal 11b do not protrude and are provided along two opposing sides, and a plurality of positive electrode collector non-coated portions 4a. 4a,..., The non-coated portions 4b, 4b,... Of the negative electrode current collector are aggregated and electrically connected to the positive electrode tab terminal 11a and the negative electrode tab terminal 11b by ultrasonic welding or the like. ing. In addition, in FIG. 2, it has a laminated structure formed by laminating a plurality of strip-shaped positive electrode plates 21, negative electrode plates 22 and separators 23, but is formed by winding a long positive electrode plate, separators and negative electrode plates. A winding structure may be used. In the winding structure, the non-coated portions 4a, 4a,... Of the positive electrode current collector and the non-coated portions 4b, 4b,. It is possible to connect with the positive electrode tab terminal 11a and the negative electrode tab terminal 11b similarly to a certain case.

  Since the battery element 9 is formed by laminating a plurality of positive electrode current collectors and negative electrode current collectors in order to increase the capacity of the battery, the non-coated portions 4a, 4a,. The non-coated portions 4b, 4b,... Of the current collector can be bundled and brought to one surface of the battery element 9, for example, the lower surface side. In this state, the positive electrode tab terminal 11a and the negative electrode tab terminal 11b substantially orthogonal to the non-coated parts 4a, 4a,... Of the positive electrode current collector and the non-coated parts 4b, 4b,. (See FIG. 1) and electrically connected to the lithium ion secondary battery 1. Therefore, the battery element 9 includes a thickness of a portion where a plurality of current collectors are stacked, a non-coated portion 4a, 4a of the positive electrode current collector, and a non-coated portion 4b, 4b of the negative electrode current collector. A step is generated between the thicknesses of the portions where the. The present invention avoids an increase in the volume of the entire battery at the time when the sealing part 19b is bent toward the battery element 9 side and fitted into the step by using such a step.

  As the material of the exterior body, aluminum, nickel-plated iron, copper and other metals, synthetic resins, etc. can be used, but a laminated composite material (hereinafter referred to as laminate) in which metal and synthetic resin are laminated. It is preferable to use a film). By using a laminate film, the entire battery can be made thinner and lighter.

  FIG. 4 is a partial cross-sectional view showing the structure of the exterior body of the lithium ion secondary battery 1 according to the embodiment of the present invention. As shown in FIG. 4A, the laminate film used as the exterior body 19 is provided with a synthetic resin layer 31 as an outer surface layer on the outer side of the metal layer 30 that is an intermediate layer, and with an inner surface layer on the inner side of the metal layer 30. A three-layer structure in which synthetic resin layers 32 are stacked may be used.

  In this case, the synthetic resin layer 31 is desirably made of a synthetic resin excellent in chemical resistance and mechanical strength, such as polyethylene, polypropylene, modified polyolefin, ionomer, amorphous polyolefin, polyethylene terephthalate, and polyamide. The synthetic resin layer 32 is preferably a chemical-resistant synthetic resin, and for example, polyethylene, polypropylene, modified polyolefin, ionomer, ethylene-vinyl acetate copolymer, or the like is preferably used.

  As shown in FIG. 4B, the laminate film used as the exterior body 19 may be a two-layer structure in which a metal layer 30 that is an outer surface layer and a synthetic resin layer 31 that is an inner surface layer are stacked. . The metal layer 30 is intended to prevent moisture from entering or maintain its shape. The metal layer 30 may be made of a single metal such as aluminum, iron, copper, nickel, titanium, molybdenum, gold, an alloy such as stainless steel or hastelloy, or a metal oxide such as aluminum oxide. Particularly preferred.

  The purpose of the synthetic resin layer 31 is to protect the battery, prevent corrosion due to the electrolyte, prevent contact between the metal layer 30 and the battery element 9, protect the metal layer 30, and the like. The synthetic resin layer 31 is a modified polypropylene which is a thermoplastic resin excellent in heat sealability. A resin such as polyethylene, polystyrene, polyamide, or ionomer may be used.

  FIG. 5 is a partial cross-sectional view showing a state where the sealing portion 19b of the exterior body 19 of the lithium ion secondary battery 1 according to the embodiment of the present invention is bent. FIG. 5A is a partial cross-sectional view showing a state before the sealing portion 19b of the exterior body 19 is bent, and FIG. 5B shows a state after the sealing portion 19b of the exterior body 19 is bent. It is a fragmentary sectional view shown. Before the sealing portion 19b of the outer casing 19 is bent, the outer casing 19 made of a laminate film is disposed so as to sandwich the battery element 9 from above and below, and the peripheral portion is heat-sealed to thereby fix the sealing portion 19b to the battery element 9. It is formed on all four sides.

  In the battery element 9, the thickness D1 of the portion where the positive plates 21, 21,..., The negative plates 22, 22,. A step D3 occurs between the non-coated portions 4a, 4a,... And the thickness D2 of the portion where the non-coated portions 4b, 4b,. The sealing portion 19b is bent toward the battery element 9 so that 19b overlaps the step. This minimizes the width in the lead-out direction of the non-coated portions 4a, 4a,... Of the positive electrode current collector of the lithium ion secondary battery 1 and the non-coated portions 4b, 4b,. Can be limited. And when the level | step difference D3 is larger than the thickness D4 of the sealing part 19b of the exterior body 19, even if it is a case where the sealing part 19b is bent to the battery element 9 side, the thickness of the battery element 9 whole is D1. Therefore, the thickness of the lithium ion secondary battery 1 is not increased. At this time, the end portions of the sealing portion 19b are respectively connected to the current collectors of the non-coated portion 4a of the positive electrode current collector and the non-coated portion 4b of the negative electrode current collector, and the positive electrode plate 21 and the negative electrode plate 22 of the battery element 9. It is bent so as to reach the vicinity of the boundary between the positive electrode mixture and the negative electrode mixture formed on the body.

  FIG. 6 is a partial plan view when the sealing portion 19b of the exterior body 19 of the conventional lithium ion secondary battery 1 is bent. 6A shows a state before the sealing portion 19b of the outer body 19 is bent, and FIG. 6B shows a state after the sealing portion 19b of the outer body 19 is bent.

  As shown in FIG. 6A, in the state before the sealing portion 19b of the outer package 19 is bent, the width of the lithium ion secondary battery (the width of the battery element 9 and the non-coated portion 4a of the positive electrode current collector, 4a,..., And the length of the non-coated portions 4b, 4b,... Of the negative electrode current collector) L1 is 200 mm, and the widths L3, L3 of the sealing portions 19b, 19b at both ends Are each 10 mm. Therefore, in a state before the sealing portion 19b of the exterior body 19 is bent, the full width L2 is 220 mm.

  Conventionally, only the sealing portions 19b and 19b are bent at substantially the center of the sealing portions 19b and 19b at both ends. Therefore, as shown in FIG. 6B, the width L4 of the folded sealing portions 19b and 19b is 5 mm, and the total width L5 can be reduced to 210 mm.

  FIG. 7 is a partial plan view when the sealing portion 19b of the exterior body 19 of the lithium ion secondary battery 1 according to the embodiment of the present invention is bent. FIG. 7A shows a state before the sealing portion 19b of the exterior body 19 is bent, and FIG. 7B shows a state after the sealing portion 19b of the exterior body 19 is bent.

  As shown in FIG. 7A, in a state before the sealing portion 19b of the outer package 19 is bent, the width L1 of the lithium ion secondary battery is set to 200 mm as in FIG. The widths L3 and L3 of 19b and 19b are 10 mm, respectively. Therefore, in a state before the sealing portion 19b of the exterior body 19 is bent, the full width L2 is 220 mm.

  However, the portion where the non-coated portions 4a, 4a,... Of the positive electrode current collector and the non-coated portion electrodes 4b, 4b,. Since the plates 21, 21,..., The negative plates 22, 22,... And the separators 23, 23,. , 19b can be bent to the battery element 9 side with a larger width than before. For example, when there is a step in thickness L6 and L6 on the battery element 9 side from the boundary between the battery element 9 and the both end positions of the sealing portions 19b and 19b, the sealing portions 19b and 19b at both ends have such a step. The sealing portions 19b, 19b at both ends can be bent at a position outside by a distance L7 from the both end positions of the battery element 9 calculated by (Equation 1).

  L7 = (L3-L6) / 2 (Formula 1)

  When L6 indicating the width of the stepped portion is 6 mm, L7 indicating the width from the both end positions of the battery element 9 to the bending position can be calculated as 2 mm based on (Equation 1). Therefore, the sealing portions 19b, 19b at both ends can be bent toward the battery element 9 at a position 2 mm outside from both end positions of the battery element 9.

  Specifically, as shown in FIG. 7B, the width L8 of each of the folded sealing portions 19b and 19b is 8 mm, and the total width L9 can be reduced to 204 mm, which is compared with the conventional bending method. 6mm size can be reduced.

  As described above, according to the present embodiment, the sealing portion 19b that seals the exterior body 19 is not coated with the non-coated portions 4a, 4a,. The thickness of the outer casing 19 including the bent sealing portion 19b and the non-coated portion 4a, 4a,... Of the positive electrode current collector or the negative electrode current collector by being bent so as to overlap the portions 4b, 4b,. Even when combined with the thickness of the portion where the non-coated portions 4b, 4b,... In addition, it is possible to provide a laminated battery in which the overall battery size does not increase in the thickness direction and the volume energy density as a lithium ion secondary battery does not decrease.

  The positive electrode tab terminal 11a and the negative electrode tab terminal 11b are drawn out from the non-coated portions 4a, 4a,... Of the positive electrode current collector and the non-coated portions 4b, 4b,. Are pulled out to the same side in a direction substantially perpendicular to the direction in which the sealing member 19b, 19b is bent, the uncoated portions 4a, 4a,... Of the positive electrode current collector and the negative electrode current collector There is no need to bend the non-coated parts 4b, 4b,... And the sealing parts 19b, 19b are non-coated parts 4a, 4a,... Of the positive electrode current collector and the non-coated parts of the negative electrode current collector. 4b, 4b,... Can be bent more closely. Therefore, the volume of the entire battery can be further reduced.

  Further, the end portions of the sealing portions 19b and 19b are the non-coated portions 4a, 4a,... Of the positive electrode current collector and the non-coated portions 4b, 4b,. It is preferable that the sealing portions 19b and 19b of the outer package 19 be bent toward the battery element 9 so as to be as close as possible to the vicinity of the connection portion. This is because the surface area required to accommodate the battery can be minimized.

  In addition, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions are possible within the scope of the gist of the present invention. For example, the width of the sealing portions 19b, 19b is made as small as possible, and the non-coated portions 4a, 4a,... Of the positive electrode current collector and the non-coated portions 4b, 4b,. -It may be bent together. In this case, the positive electrode tab terminal 11a and the negative electrode tab terminal 11b are connected to the tip portions of the non-coated portions 4a, 4a,... Of the positive electrode current collector and the non-coated portions 4b, 4b,. Or it is not necessary to bend the positive electrode tab terminal 11a and the negative electrode tab terminal 11b by connecting in the battery element 9 vicinity. Even with such a configuration, the size required to accommodate the battery can be reduced, the volume of the entire battery is not increased in the thickness direction, and the volume energy density as a secondary battery is reduced. It becomes possible to provide a laminate battery that does not.

4a End of positive electrode current collector (non-coated part)
4b End of negative electrode current collector (non-coated part)
DESCRIPTION OF SYMBOLS 9 Battery element 11a Positive electrode tab terminal 11b Negative electrode tab terminal 19 Exterior body 19b Sealing part 21 Positive electrode plate 22 Negative electrode plate 23 Separator

Claims (3)

A package body made of a laminate film, a battery element sealed by a sealing portion of the package body, and a positive electrode tab that is electrically connected to the battery element inside and protrudes outside from the package body In a substantially square laminated battery comprising a terminal and a negative electrode tab terminal,
In the battery element, the ends of the positive electrode current collector and the negative electrode current collector are provided along two opposing sides of the exterior body,
The laminated battery, wherein the sealing portion of the outer package is bent so as to overlap the end portions of the positive electrode current collector and the negative electrode current collector, respectively.   The laminate battery according to claim 1, wherein the positive electrode tab terminal and the negative electrode tab terminal protrude substantially in parallel from the same side different from the two opposite sides of the outer package.   End portions of the sealing portion are formed on the positive electrode current collector and the negative electrode current collector, and on the positive electrode current collector and the negative electrode current collector. The laminated battery according to claim 1 or 2, wherein the sealing portion of the outer package is bent toward the battery element side so as to reach the vicinity of the boundary portion.

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