JP2016167470A - Manufacturing method of flat nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a flat nonaqueous secondary battery which improves productivity.SOLUTION: A flat nonaqueous secondary battery includes an electrode group in which positive electrodes and negative electrodes are alternately laminated via separators substantially in parallel with flat surfaces of an exterior case and a sealing case within a space that is formed by caulking and sealing a positive electrode case and a negative electrode case via an insulation gasket. Collector tab parts of the positive electrodes or the negative electrodes are collectively welded, integrated and folded on the electrodes of the same pole closer to an outermost part of the electrode group. An end of a welding portion of the integrated collector tab parts of the positive electrodes or the negative electrodes is positioned closer to the inside of the battery than an outermost part of the integrated collector tab parts of the positive electrodes or the negative electrodes closer to the insulation gasket. When manufacturing such a flat nonaqueous secondary battery, the manufacturing method of the flat nonaqueous secondary battery includes folding and collecting the collector tab parts of the electrodes onto the electrode at the outermost part of the electrode group while forcedly creasing the collector tab parts, and then welding and integrating the collector tab parts with each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a flat non-aqueous secondary battery excellent in productivity and a method for manufacturing the same.

  In a flat non-aqueous secondary battery generally referred to as a coin-type battery or a button-type battery, an electrode group in which a positive electrode and a negative electrode are opposed to each other with a separator interposed therebetween, and a non-aqueous electrolyte solution are provided in an outer case. And a structure accommodated in a space formed by a sealing case and an insulating gasket.

  In the flat non-aqueous secondary battery as described above, a positive electrode mixture layer or a negative electrode agent layer is formed on one or both surfaces of the current collector on the positive electrode and the negative electrode, and a part of the current collector is mixed with the positive electrode mixture. It is exposed without forming a layer or a negative electrode agent layer, and this is used as a current collecting tab. The current collecting tabs of each positive electrode and each negative electrode are welded together, and these collected current collecting tabs are connected to terminals. There are some which are used for electrical connection with the inner surface of an exterior case or a sealing case that also serves as a material (for example, Patent Document 1).

  In recent years, as the application range of flat non-aqueous secondary batteries has expanded, for example, there has been a demand for downsizing. However, in a flat non-aqueous secondary battery, depending on the shape of the battery, such as a small one, the inside of the battery is very narrow. Welding with the inner surface of the sealing case may be difficult, and battery productivity may be impaired.

  Therefore, the plurality of current collecting tabs welded together are folded and bonded to the outer surface side of the electrode group, and are brought into contact with the inner surfaces of the positive electrode case and the negative electrode case to be electrically connected to each other. There is also a proposal of a technique that enables the application of a small battery case while ensuring a certain degree (Patent Document 2).

JP 2003-142161 A JP 2011-141997 A

  However, the technique described in Patent Document 2 also has a problem that it is difficult to fit the positive electrode case and the negative electrode case, particularly in a thin flat non-aqueous secondary battery having a small thickness with respect to the diameter in plan view. This problem also affects productivity. In this respect, the technique described in Patent Document 2 still leaves room for improvement.

  This invention is made | formed in view of the said situation, The objective is to provide the flat type non-aqueous secondary battery excellent in productivity, and its manufacturing method.

  A positive electrode case that also serves as a positive electrode terminal and a negative electrode case that also serves as a negative electrode terminal are formed in a space formed by caulking and sealing via an insulating gasket. A flat non-aqueous secondary battery having a non-aqueous electrolyte and an electrode group in which the total number of positive and negative electrodes is three or more, and is laminated substantially parallel to the flat surface of the negative electrode case. ) Or (2).

(1) The negative electrode includes a main body portion and a current collecting tab portion that protrudes from the main body portion in a plan view and is narrower than the main body portion. A negative electrode layer containing a negative electrode active material is formed on one side or both sides of a current collector. In the current collector tab portion of the negative electrode, a negative electrode layer is not formed on the current collector. It has at least two negative electrodes, and the outermost electrode on the negative electrode case side in the electrode group is a negative electrode, and the current collecting tab portions of the negative electrodes are gathered together and welded together, and The integrated negative electrode current collecting tab portion is folded on the outermost negative electrode on the negative electrode case side in the electrode group, and the welded portion of the integrated negative electrode current collecting tab portion on the negative electrode body portion side Is an insulating gasket in the current collecting tab portion of the integrated negative electrode Than most external, it is located in the battery inside.

(2) The positive electrode has a main body portion and a current collecting tab portion that protrudes from the main body portion in a plan view and is narrower than the main body portion. A positive electrode mixture layer containing a positive electrode active material is formed on one side or both sides of the current collector, and in the current collector tab portion of the positive electrode, a positive electrode mixture layer is not formed on the current collector, and the electrode group is , Having at least two positive electrodes, and the outermost electrode on the positive electrode case side in the electrode group is a positive electrode, and the current collecting tab portions of the positive electrodes are collected and welded together to be integrated The integrated current collecting tab portion of the positive electrode is folded on the outermost positive electrode on the positive electrode case side in the electrode group, and the positive electrode main body of the welded portion of the integrated positive electrode current collecting tab portion The end on the part side is the insulating gasket in the current collecting tab part of the integrated positive electrode. Than the outermost portion of the door side, it is located in the battery inside.

  In the flat nonaqueous secondary battery of the present invention according to the aspect (1), after the positive electrode, the negative electrode, and the separator are stacked, the current collecting tab portion of each negative electrode is forced on the outermost negative electrode of the electrode group. It can be manufactured by the manufacturing method of the present invention, which includes a step of folding and collecting together with creases, and then welding together to integrate the current collecting tab portions of the negative electrodes.

  The flat non-aqueous secondary battery of the present invention according to the above aspect (2) includes a positive electrode, a negative electrode, and a separator, and the current collecting tab portion of each positive electrode is placed on the positive electrode that is the outermost part of the electrode group. Can be manufactured by the manufacturing method of the present invention, which includes a step of forcing the current collecting tabs of the respective positive electrodes together by folding them together while forcibly folding them together.

  In the battery industry, a flat battery with a diameter larger than the height is called a coin-type battery or a button-type battery, but there is a clear gap between the coin-type battery and the button-type battery. There is no difference, and the flat non-aqueous secondary battery of the present invention includes both coin-type batteries and button-type batteries.

  ADVANTAGE OF THE INVENTION According to this invention, the flat type non-aqueous secondary battery excellent in productivity and its manufacturing method can be provided.

It is a longitudinal cross-sectional view which represents typically an example of the flat non-aqueous secondary battery of this invention. It is a principal part expanded view of the flat non-aqueous secondary battery of FIG. It is a top view which represents typically an example of the negative electrode which concerns on the flat nonaqueous secondary battery of this invention. It is a top view which represents typically an example of the positive electrode which concerns on the flat nonaqueous secondary battery of this invention. It is a principal part expanded view which represents typically an example of the flat type non-aqueous secondary battery manufactured by methods other than this invention method. It is a longitudinal cross-sectional view which represents typically the other example of the flat nonaqueous secondary battery of this invention. FIG. 7 is an enlarged cross-sectional view of a main part of the flat nonaqueous secondary battery in FIG. 6. It is a top view which represents typically an example of the separator which concerns on the flat nonaqueous secondary battery of this invention.

  1 and 2 schematically show an example of the flat non-aqueous secondary battery of the present invention. FIG. 1 is a longitudinal sectional view of a flat non-aqueous secondary battery, and FIG. 2 is an enlarged sectional view of a main part of FIG.

  As shown in FIG. 1 and FIG. 2, the flat non-aqueous secondary battery 1 includes a plurality of positive electrodes 5 and a plurality of negative electrodes 6 with separators 7 interposed therebetween, and their planes are substantially parallel (parallel) to the flat surface of the battery. And a non-aqueous electrolyte solution (not shown) are a positive electrode case 2 (exterior case in FIG. 1), and a negative electrode case 3 (also an outer case) (also shown in FIG. 1). In FIG. 1, it is accommodated in the space (sealed space) formed by the sealing case) and the insulating gasket 4. The negative electrode case 3 is fitted in the opening of the positive electrode case 2 via an insulating gasket 4, and the opening end of the positive electrode case 2 is tightened inward, whereby the insulating gasket 4 contacts the negative electrode case 3. Thus, the opening of the positive electrode case 2 is sealed, and the inside of the battery has a sealed structure. The positive electrode case 2 and the negative electrode case 3 are made of a metal such as stainless steel, and the insulating gasket 4 is made of an insulating resin such as polypropylene.

  1 and 2, as described above, the positive electrode case 2 that also serves as the positive electrode terminal is an outer case, and the negative electrode case 3 that also serves as a negative electrode terminal is a sealing case. In the battery of the present invention, for example, Depending on the configuration of the electrode group, the outer case may be a negative electrode case that also serves as a negative electrode terminal, and the sealing case may be a positive electrode case that also serves as a positive electrode terminal.

  3 schematically shows a plan view of the negative electrode 6. The negative electrode 6 has a width that is larger than the main body 600 and the main body 600 protruding from the main body 600 in plan view (up and down in FIG. 3). Current collecting tab portion 601 having a narrow direction length). The width of the current collecting tab portion 601 can be set to 5 to 60% of the width of the main body portion 600, for example.

  In the main body 600 of the negative electrode 6, a negative electrode agent layer 61 containing a negative electrode active material or the like is formed on one side or both sides of a current collector (62 in FIG. 1). And the current collection tab part 601 of the negative electrode 6 does not have the negative electrode agent layer formed in the surface of the electrical power collector 62, and the electrical power collector 62 is exposed.

  In the battery shown in FIG. 1 and FIG. 2, the upper and lower ends of the electrode group are negative electrodes 6B and 6B, and these negative electrodes 6B and 6B are provided on only one side of the current collector 62 (the inner surface of the battery). A layer 61 is provided. On the other hand, the negative electrode 6 </ b> A arranged on the electrode group other than the upper and lower ends has negative electrode agent layers 61 and 61 on both surfaces of the current collector 62. In addition, the negative electrode arrange | positioned at the outermost side of an electrode group may also have a negative electrode agent layer on both surfaces of a collector.

  4 schematically shows a plan view of the positive electrode 5. The positive electrode 5 has a width that is larger than the main body 500 and the main body 500 protruding from the main body 500 in plan view (upper and lower in FIG. 4). Current collecting tab portion 501 having a narrow direction length). The width of the current collecting tab portion 501 can be set to 5 to 60% of the width of the main body portion 500, for example.

  In the main body 500 of the positive electrode 5, a positive electrode mixture layer 51 containing a positive electrode active material or the like is formed on both surfaces of a current collector (52 in FIG. 1). In the current collecting tab portion 501 of the positive electrode 5, the positive electrode mixture layer is not formed on the surface of the current collector 52, and the current collector 52 is exposed. In the batteries shown in FIGS. 1 and 2, since the outermost electrode in the electrode group is a negative electrode, the positive electrode mixture is formed on both surfaces of the current collector 52 in the main body portion 500 of all the positive electrodes 5. Although the layer 51 is formed, for example, one of the electrodes on the outermost side in the electrode group (more specifically, the electrode on the exterior case side or the sealing case side that also serves as the positive electrode terminal) or both is used as the positive electrode. In this case, the outermost positive electrode in the electrode group may have a positive electrode mixture layer only on one side of the current collector (the inner surface of the battery) in the main body, and the positive electrode mixture layer on both sides. You may have an agent layer.

  Further, in the battery shown in FIG. 1, the current collecting tab portions of all the positive electrodes 5 constituting the electrode group are collected, and these are welded and integrated, and the end portions thereof are outside the electrode group in plan view ( It is bent so as to face the left side in the figure. The positive current collecting tab portion 501 a which is integrated and welded is welded to the inner surface of the positive electrode case 2.

  On the other hand, in the battery shown in FIG. 1 and FIG. 2, the current collecting tab portions 601 of all the negative electrodes 6 constituting the electrode group are integrated and welded together, and the outermost electrode on the negative electrode case 3 side in the electrode group. It is folded on the external negative electrode 6B and is sandwiched between the outer surface of the electrode group (upper surface in FIGS. 1 and 2) and the inner surface of the negative electrode case. Then, the end X of the negative electrode main body portion side of the welded portion of the integrated negative electrode current collecting tab portion 601a is closer to the inside of the battery than the outermost Y on the insulating gasket side of the integrated negative electrode current collecting tab portion. Is located. As shown in FIGS. 1 and 2, the end of the negative electrode body tab side in the welded portion of the integrated negative electrode current collector tab portion is the outermost portion on the insulating gasket side in the integrated negative electrode current collector tab portion. The flat nonaqueous secondary battery located inside the battery can be manufactured by the manufacturing method of the present invention including a step of welding the current collecting tab portion of each negative electrode by a specific method.

  FIG. 5 shows an enlarged cross-sectional view of a main part schematically showing a flat non-aqueous secondary battery manufactured by a manufacturing method different from the method of the present invention. The battery 100 shown in FIG. 5 is formed by laminating the positive electrode 5, the negative electrodes 6A and 6B, and the separator 7 to form an electrode group, and then collecting and integrating the current collecting tab portions of the negative electrodes together. The integrated negative electrode current collecting tab portion 601a is manufactured through a step of folding back on the outermost negative electrode 6B of the electrode group.

  In the battery manufactured by such a manufacturing method, the outermost negative electrode of the electrode group in a state where the positions of the current collecting tab portions of the negative electrodes constituting the integrated negative current collecting tab portion 601a are fixed. 6B, because the current collecting tab portion on the inner side is bent, and the length of the current collecting tab portion on the outer side is insufficient, the return is generated even if it is turned back and integrated. The negative electrode current collecting tab portion 601a cannot be satisfactorily placed on the outer surface of the outermost negative electrode 6B of the electrode group, and is raised. When the battery is assembled with the tip of the integrated negative electrode current collecting tab portion 601a raised, workability when the electrode group is loaded and the positive electrode case and the negative electrode case are fitted decreases. There is a possibility that the productivity of the battery may be reduced because the generation ratio of non-defective products increases or an operation for suppressing the generation of defective products becomes necessary.

  And in the case of a flat non-aqueous secondary battery that is manufactured through a process of folding back on the outermost negative electrode of the electrode group after welding and integrating the current collecting tab portion of each negative electrode, As shown in FIG. 5, the end X on the negative electrode body portion side of the welded portion of the integrated negative electrode current collector tab portion 601a is connected to the insulating gasket side of the integrated negative electrode current collector tab portion. It comes to be located in the outermost Y.

  On the other hand, in the method of the present invention, after the positive electrode, the negative electrode, and the separator are laminated, the current collecting tab portion of each negative electrode is folded and forcedly folded on the negative electrode that is the outermost part of the electrode group. Then, a flat non-aqueous secondary battery is manufactured through a process of welding each other and integrating the current collecting tab portions of the negative electrodes. When manufactured by such a method, the current collecting tabs of the integrated negative electrode are fixed on the outermost negative electrode of the electrode group by welding in a state where the positions of the current collecting tabs are fixed. The occurrence of the return in step 1 can be suppressed. For this reason, it is possible to avoid the problems during the battery assembly as described above and increase the productivity of the battery.

  And in the flat non-aqueous secondary battery manufactured by the method of the present invention, as shown in FIG. 2, the end X on the main body side of the negative electrode in the welded portion of the integrated negative electrode current collecting tab 601a is The integrated negative electrode current collecting tab portion is located on the inner side of the battery with respect to the outermost Y on the insulating gasket side.

  The end X on the negative electrode body portion side in the welded portion of the integrated negative electrode current collecting tab portion 601a is the integrated negative electrode current collecting tab portion in plan view (plan view from the battery upper surface in FIG. 1). It is preferable that it is 0.3-2.6 mm away from the position of the outermost Y on the insulating gasket side.

  As shown in FIGS. 1 and 2, a part of the integrated negative electrode current collecting tab portion is sandwiched between the outer surface of the electrode group and the inner surface of the negative electrode case. Are electrically connected to the negative electrode case.

  FIG. 1 shows a case where both of the two electrodes on the outermost side of the electrode group are negative electrodes. As described above, in the battery of the present invention, either one of the outermost side of the electrode group One or both may be positive.

  In such a flat non-aqueous secondary battery, after the positive electrode, the negative electrode, and the separator are stacked, the current collecting tab portion of each positive electrode is folded back on the positive electrode that is the outermost part of the electrode group while being forcibly folded. It is manufactured by the method of the present invention, which includes a step of integrating the current collecting tab portions of each positive electrode by welding them together. In this case, as in the case of the flat non-aqueous secondary battery manufactured through the process of integrating the negative electrode current collecting tab part by the above-described method, the integrated positive electrode current collecting tab part is the outermost electrode group. Since it is possible to suppress lifting from the external positive electrode, it is possible to suppress a decrease in battery productivity due to such lifting.

  And after stacking the positive electrode, the negative electrode, and the separator, the current collecting tab portion of each positive electrode is forcibly folded and folded on the positive electrode that is the outermost part of the electrode group, and then welded together, In the flat type non-aqueous secondary battery manufactured by the method of the present invention having the step of integrating the current collecting tab portion of each positive electrode, the end of the positive electrode body portion side in the welded portion of the current collecting tab portion of the integrated positive electrode However, it comes to be located inside a battery rather than the outermost part by the side of the insulation gasket in the current collection tab part of the said integrated positive electrode.

  The end on the main body side of the positive electrode current collector tab portion welded portion of the integrated positive electrode is 0.3 mm from the outermost position on the insulating gasket side in the integrated current collector tab portion of the positive electrode. It is preferable to be separated by ~ 2.6 mm.

  In addition, in the case of the battery of this aspect, a part of the integrated current collecting tab portion of the positive electrode is sandwiched between the outer surface of the electrode group and the inner surface of the positive electrode case, so that each positive electrode serves as both the positive electrode and the positive electrode terminal. The case is electrically connected.

  As shown in FIG. 1, when the two electrodes on the outermost side of the electrode group are both negative electrodes, the positive electrode case (the outer case in FIGS. 1 and 2) and the electrode group (the outermost negative electrode) An insulating seal (8 in FIG. 1) made of, for example, a tape formed of polyethylene terephthalate (PET) or polyimide may be disposed between them.

  Also, for example, when the two electrodes on the outermost side of the electrode group are both positive electrodes, the electrical connection between the negative electrode and the negative electrode case (exterior case or sealing case) associated with the electrode group is, for example, Collecting and collecting the current collecting tabs of all the negative electrodes together and integrating them together, as shown in FIGS. 1 and 2, the end portions and the like of the negative electrode are not folded over the negative electrode on the outer surface side of the electrode group. It can be performed by welding to the inner surface of the case.

  When the two electrodes on the outermost side of the electrode group are both positive electrodes, for example, a tape formed of PET or polyimide is formed between the negative electrode case and the electrode group (the outermost positive electrode). An insulating seal may be arranged.

  In the battery of the present invention, one of the two electrodes on the outermost side of the electrode group can be a negative electrode and the other can be a positive electrode. In this case, the current collecting tab portion of each negative electrode in the electrode group has the same configuration as that described above in the case where the two outermost electrodes in the electrode group are both negative electrodes (that is, the negative electrode current collecting tabs). Applying the process according to the method of the present invention that specifies the process of integrating the electric tab part), and for the current collecting tab part of each positive electrode related to the electrode group, the outermost two electrodes of the electrode group are both The configuration of the positive electrode can be the same as the configuration described above (that is, the step according to the present invention specifying the step of integrating the current collecting tab portion of the positive electrode can be applied).

  As shown in FIGS. 1 and 2, when the integrated current collecting tab portion of the negative electrode is folded over the outermost negative electrode of the electrode group, the integrated negative electrode current collecting tab portion is directed toward the positive electrode case side. To some extent. In this case, the current collecting tabs of the individual negative electrodes can be lengthened to some extent. Therefore, particularly in the case of a small and thin flat non-aqueous secondary battery, the current collecting tabs of the respective negative electrodes are integrated. This improves the workability of the welding process. However, in this case, in order to prevent the current collecting tab portion of the integrated negative electrode from coming into contact with the positive electrode case, the length of the loosened portion is such that the end portion does not reach the positive electrode case ( For example, the thickness is preferably less than the thickness of the electrode group.

On the other hand, when the integrated current collecting tab portion of the positive electrode is folded on the outermost positive electrode of the electrode group, the integrated positive electrode current collecting tab portion may have some slack toward the negative electrode case side. Good.
In this case, since the current collecting tabs of individual positive electrodes can be made somewhat long, the current collecting tabs of each positive electrode are integrated, particularly in the case of a small and thin flat non-aqueous secondary battery. This improves the workability of the welding process. However, also in this case, in order to prevent the current collecting tab portion of the integrated positive electrode from coming into contact with the negative electrode case, the length of the loosened portion is long enough not to reach the negative electrode case. It is preferable to set the thickness (for example, less than the thickness of the electrode group).

  In the battery of the present invention, the two separators arranged on both surfaces of the positive electrode can be welded to each other at at least a part of their peripheral portions to form a joint portion.

  6 and 7 schematically show another example of the flat non-aqueous secondary battery of the present invention. The battery shown in FIGS. 6 and 7 has a group of electrodes formed by forming joints at the peripheral edges of the two separators 7 and 7 arranged on both surfaces of the positive electrode 5, and FIG. FIG. 7 is a longitudinal sectional view showing a cross section of the positive electrode case 2, the negative electrode case 3, and the insulating gasket 4, and FIG. 7 is an enlarged view of the main part of FIG. 6 and a cross section of the electrode group.

  FIG. 8 schematically shows a plan view of a separator in which a joining portion is formed on a part of the peripheral edge. In FIG. 8, assuming the case of a stacked electrode group in which the positive electrode, the negative electrode, and the separator are stacked together with the separator 7, the positive electrode 5 disposed under the separator 7 is indicated by a dotted line, A current collecting tab portion 601 relating to the negative electrode disposed on the lower side is indicated by a one-dot chain line, and a binding tape 9 for suppressing positional deviation of each component relating to the electrode group is indicated by a two-dot chain line. Further, the positive electrode 5 shown in FIG. 8 is one in which both sides (both sides) of the electrode group are opposed to the negative electrode. Although not shown in FIG. In the forward direction), at least a negative electrode is arranged.

  The separator 7 shown in FIG. 8 is joined to another separator disposed on the lower side (in the depth direction in the drawing) via the positive electrode 5 (indicated by a dotted line in the drawing), and a joint 7c (FIG. Middle). That is, the separator 7 and the separator disposed below the separator 7 are welded to each other at the peripheral edge to form a bag shape, and the positive electrode 5 is accommodated therein.

  The separator 7 shown in FIG. 8 includes a main body part 7a (that is, a main body part 7a having a larger area in plan view than the main body part 5a of the positive electrode 5) and the main body part 7a. It has a protruding portion 7b that protrudes and covers at least a portion of the current collecting tab portion 5b of the positive electrode 5 that includes a boundary portion with the main body portion 5a. Then, two separators (the separator 7 and the separator disposed below the positive electrode 5) disposed on both surfaces of the positive electrode 5 were welded to at least a part of the peripheral portion of the main body portion 7 a of the separator 7. A joint 7c is provided.

  As separators for non-aqueous secondary batteries, a microporous film made of a thermoplastic resin that is easily heat-shrinkable at high temperatures is generally used. In this way, two sheets arranged on both sides of the positive electrode are used. In this separator, the peripheral portions are welded to each other to form a joint portion, so that, for example, even if the inside of the battery becomes high temperature, the thermal contraction of the separator is suppressed, so that a safer battery is configured. be able to.

  In addition, as shown in FIG. 8, when using the separator which has a main-body part and an overhang | projection part, the junction part for joining two separators arrange | positioned on both surfaces of a positive electrode is a peripheral part of the main-body part of a separator However, a joining portion may also be provided at the peripheral portion of the separator overhanging portion (the portion of the peripheral edge portion of the separator overhanging portion along the protruding direction from the main body portion).

  The joining portion may be formed by directly welding the peripheral portions of the two separators, but a layer made of a thermoplastic resin is interposed between the two separators, and two sheets are interposed via this layer. The separator may be formed by welding. However, in the latter case, depending on the type of thermoplastic resin that constitutes the layer interposed between the separators and the type of thermoplastic resin that constitutes the separator, the strength of the joint may be reduced. It is preferable to use the layer made of the same kind of resin as the thermoplastic resin constituting the separator. That is, when the separators are welded directly, or when the separators are welded via a layer composed of the same type of resin as the thermoplastic resin that constitutes the separator, the strength of the joint is determined by the strength of the separator itself. Since they are almost the same, for example, separation at a joint portion that may occur due to vibration or the like when the battery is used can be satisfactorily suppressed, and a battery with higher reliability can be obtained.

  In addition, when using the separator which has a main-body part and an overhang | projection part as shown in FIG. 8, all the peripheral parts which concern on the main-body part of a separator may be a junction part, For example, it shows in FIG. Thus, you may leave a part of peripheral part as the non-welding parts 7d and 7d, without welding separators. After the two separators are welded to form a bag, the positive electrode is accommodated therein, the positive electrode is disposed on one separator, and the separator is further disposed on the positive electrode. When the positive electrode is housed in a separator that is welded to form a bag, air may remain in the separator. However, when manufacturing a battery using such a positive electrode, when the outer case and the sealing case are caulked, the residual air is well discharged outside the separator through the non-welded portions 7d and 7d. Occurrence of problems due to residual air in the separator (problems such as non-uniform reaction during power generation and reduced capacity) can be prevented.

  When providing a non-welding part in the peripheral part of a separator, it is preferable that the number shall be about 1-5 from a viewpoint of suppressing the productivity fall of a battery. Moreover, when providing a non-welding part in the peripheral part of a separator, the length of the outer edge of the non-welding part related to the main part of the separator is the total length of the outer edge related to the main part of the separator (the total length of the outer edge excluding the overhanging part). Is preferably about 15 to 60%. That is, in the main part of the separator, it is preferable that 40% or more (preferably 70% or more) of the entire length of the outer edge is a joined part, thereby ensuring good joining strength between the separators. Can do.

  In order to form a joint part at the peripheral part of two separators and to accommodate a positive electrode between these separators, when two separators are directly welded together to form a joint part, for example, one sheet It is possible to employ a method in which the positive electrode is overlaid on the separator, the separator is further overlaid thereon, and then the peripheral portions of these separators are welded. It is also possible to adopt a method in which two separators are stacked, the peripheral portions thereof are welded to join the separators, and then the positive electrode is inserted between these separators.

  On the other hand, when a layer composed of the same kind of resin as the constituent resin of the separator is interposed between the two separators and these are welded to form a joint, for example, the joint on one separator It is possible to adopt a method in which a film to be the layer is placed at a place where the layer is expected to be placed, a positive electrode is disposed on the separator, and a separator is further stacked thereon, and then the peripheral portions of these separators are welded. . In addition, a film to be the layer is placed in a place where it is planned to become a joint portion on one separator, and the separator and the film are previously welded. Adopting a method of laminating the peripheral portion by overlapping, or a method of inserting a positive electrode between these separators after forming a joined portion by interposing a film serving as the layer between two separators. You can also.

  For example, the peripheral edge of the separator can be welded by a hot press. In this case, the heating temperature may be a temperature higher than the melting point of the thermoplastic resin constituting the separator, but for example, the heating temperature is preferably 10 to 50 ° C. higher than the melting point. Moreover, about the time of a hot press, if a junction part can be formed satisfactorily, there will be no restriction | limiting, However, Usually, it shall be about 1 to 10 second.

  In addition, the planar shape of the separator used for the battery of the present invention is, for example, at least a part of the peripheral part of the separator as described above at least at the joint part (at least the peripheral part of the two separators arranged on both surfaces of the positive electrode). In the case of forming a joint portion formed by welding a part of each other, the shape shown in FIG. 8 is preferable. However, even when the joint portion is not formed, the shape shown in FIG. Is preferred.

  In the battery of the present invention, when forming the electrode group, separators are arranged on both sides of the positive electrode at least on both sides facing the negative electrode, but only the positive electrode arranged on the outermost side of the electrode group, that is, only one side (one side). As for the positive electrode facing the negative electrode, separators may be disposed on both sides thereof (joint portions may be formed on these two separators), or only on the surface facing the negative electrode. You may arrange. Furthermore, when all the outermost electrodes in the electrode group are positive electrodes and no separator is disposed on both surfaces of these positive electrodes, the battery case that also serves as the negative electrode terminal and the outermost positive electrode of the electrode group are between As described above, an insulator such as an insulating seal made of tape or the like made of PET or polyimide is disposed.

  Heretofore, the flat non-aqueous secondary battery of the present invention has been described with reference to FIGS. 1 to 8, but FIGS. 1 to 8 were created to facilitate the description of the present invention. However, the shape and size of each member shown on the bottom are not necessarily accurate.

  The positive electrode mixture layer of the positive electrode according to the battery of the present invention is a layer containing a positive electrode active material, a conductive additive, a binder and the like.

Examples of the positive electrode active material according to the battery of the present invention include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O ₂ , and Li _x Co _y M _1-y O _2. lithium transition metal composite such as _{Li x Ni 1-y M y} O 2, Li x Mn y Ni z Co 1-y-z O 2, Li x Mn 2 O 4, Li x Mn 2-y M y O 4 (However, in each of the above lithium transition metal composite oxides, M is at least one selected from the group consisting of Mg, Mn, Fe, Co, Ni, Cu, Zn, Al, and Cr.) It is a metal element, and 0 ≦ x ≦ 1.1, 0 <y <1.0, and 2.0 ≦ z ≦ 2.2.) These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together.

  Moreover, as a conductive support agent of a positive electrode, carbon black, scale-like graphite, ketjen black, acetylene black, fibrous carbon etc. are mentioned, for example. Furthermore, examples of the binder for the positive electrode include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), carboxymethyl cellulose, and styrene butadiene rubber.

  For the positive electrode, for example, a positive electrode mixture obtained by mixing a positive electrode active material, a conductive additive, and a binder is dispersed in water or an organic solvent to prepare a positive electrode mixture-containing paste (in this case, the binder is preliminarily mixed with water or It may be dissolved or dispersed in a solvent and mixed with a positive electrode active material or the like to prepare a positive electrode mixture-containing paste), and the positive electrode mixture-containing paste is made of metal foil, expanded metal, plain weave metal mesh, etc. It is manufactured by forming a positive electrode mixture layer by applying it to one or both sides of a current collector, drying it, and then press-molding it. However, the method for manufacturing the positive electrode is not limited to the above-described method, and other methods may be used.

  As a composition of the positive electrode, for example, in 100% by mass of the positive electrode mixture constituting the positive electrode, the positive electrode active material is 75 to 90% by mass, the conductive additive is 5 to 20% by mass, and the binder is 3 to 15% by mass. Is preferred. Moreover, it is preferable that the thickness of a positive mix layer is 30-200 micrometers, for example.

  The material for the current collector of the positive electrode is preferably aluminum or an aluminum alloy. From the viewpoint of reducing the total thickness of the positive electrode and increasing the number of layers of the positive electrode and the negative electrode in the battery to increase the facing area between the positive electrode mixture layer and the negative electrode agent layer and improving the load characteristics of the battery, It is preferable to use a metal foil for the current collector. Moreover, it is preferable that the thickness of a collector is 8-20 micrometers, for example.

  Examples of the negative electrode according to the battery of the present invention include a negative electrode having lithium, a lithium alloy, a carbon material capable of occluding and releasing lithium ions, lithium titanate, and the like as an active material.

  Examples of the lithium alloy that can be used for the negative electrode active material include lithium alloys that reversibly alloy with lithium, such as lithium-aluminum and lithium-gallium, and the lithium content is, for example, 1 to 15 atomic%. Is preferred. Examples of the carbon material that can be used for the negative electrode active material include artificial graphite, natural graphite, low crystalline carbon, coke, and anthracite.

The lithium titanate that can be used for the negative electrode active material is represented by the general formula Li _x Ti _y O ₄ , and x and y are 0.8 ≦ x ≦ 1.4 and 1.6 ≦ y ≦ 2.2, respectively. Lithium titanate having a stoichiometric number is preferable, and lithium titanate having a stoichiometric number of x = 1.33 and y = 1.67 is particularly preferable. The lithium titanate represented by the general formula Li _x Ti _y O ₄ can be obtained, for example, by heat-treating titanium oxide and a lithium compound at 760 to 1100 ° C. As the titanium oxide, either anatase type or rutile type can be used, and examples of the lithium compound include lithium hydroxide, lithium carbonate, and lithium oxide.

  When the negative electrode active material is lithium or a lithium alloy, the negative electrode is formed by bonding the lithium or lithium alloy to a current collector such as a metal network to form a negative electrode layer made of lithium or lithium alloy on the surface of the current collector. Can be obtained. On the other hand, when a carbon material or lithium titanate is used as the negative electrode active material, for example, a negative electrode composite obtained by mixing a carbon material or lithium titanate with a binder as the negative electrode active material and, if necessary, a conductive additive. The negative electrode mixture-containing paste is prepared by dispersing the agent in water or an organic solvent (in this case, the binder is previously dissolved or dispersed in water or solvent, and mixed with the negative electrode active material or the like to contain the negative electrode mixture) The paste containing the negative electrode mixture may be applied to a current collector made of metal foil, expanded metal, plain weave metal mesh, etc., dried, and then pressed to form a negative electrode layer (negative electrode composite). The negative electrode can be produced by forming an agent layer. However, the manufacturing method of the negative electrode is not limited to the above-described method, and other methods may be used.

  In addition, as a binder and conductive support agent which concern on a negative electrode, the various binders and conductive support agent which were illustrated previously as what can be used for a positive electrode can be used.

  The composition of the negative electrode when a carbon material is used as the negative electrode active material is, for example, that the carbon material is 80 to 95% by mass and the binder is 3 to 15% by mass in 100% by mass of the negative electrode mixture constituting the negative electrode. Moreover, when using together a conductive support agent, it is preferable that a conductive support agent shall be 5-20 mass%. On the other hand, the composition of the negative electrode when lithium titanate is used as the negative electrode active material is, for example, 75 to 90% by mass of lithium titanate and 3 to 15% by mass of the binder in 100% by mass of the negative electrode mixture constituting the negative electrode. In addition, when a conductive auxiliary is used in combination, the conductive auxiliary is preferably 5 to 20% by mass.

  The thickness of the negative electrode layer (including the negative electrode mixture layer) in the negative electrode is preferably 40 to 200 μm, for example.

  The material for the current collector of the negative electrode is preferably copper or a copper alloy. From the viewpoint of reducing the total thickness of the negative electrode and increasing the number of layers of the positive electrode and negative electrode in the battery to increase the facing area between the positive electrode mixture layer and the negative electrode agent layer, and improving the load characteristics of the battery, It is preferable to use a metal foil for the current collector. Moreover, it is preferable that the thickness of a collector is 5-30 micrometers, for example.

  A separator made of a microporous film made of a thermoplastic resin is used. As the thermoplastic resin constituting the separator, for example, polyolefins such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, polymethylpentene, and the like are preferable. From the viewpoint of arranging and welding the same type of resin as the constituent resin, the melting point, that is, the melting temperature measured using a differential scanning calorimeter (DSC) in accordance with the provisions of JIS K 7121 is 100. A polyolefin of ˜180 ° C. is more preferable.

  As the form of the microporous film made of the thermoplastic resin constituting the separator, any form may be used as long as it has an ionic conductivity sufficient to obtain the required battery characteristics. Or the ion-permeable microporous film (microporous film currently used widely as a battery separator) which has many holes formed by the wet extending | stretching method etc. is preferable.

  The thickness of the separator is preferably, for example, 5 to 25 μm, and the porosity is preferably, for example, 30 to 70%.

  The positive electrode, the negative electrode, and the separator are stacked and used as a stacked electrode group as shown in FIG. 1, FIG. 2, FIG. 6, and FIG. 7. It is preferable that the electrodes are arranged so as to face in the same direction in the plan view of the group, and the current collecting tab portions of the respective negative electrodes are arranged so as to face in the same direction in the plan view of the electrode group. Thereby, current collection of the positive electrode and the negative electrode becomes easier.

  Furthermore, the current collecting tab portion of each positive electrode and the current collecting tab portion of each negative electrode only need to be arranged so as not to contact each other in a plan view of the electrode group, but these contacts are better suppressed, In addition, from the viewpoint of improving battery production, as shown in FIG. 8, the current collecting tab portion 501 of each positive electrode and the current collecting tab portion 601 of each negative electrode face each other in a plan view of the electrode group. More preferably, it is arranged at a position where

  Further, as shown in FIG. 8, the electrode group formed by laminating the positive electrode, the negative electrode, and the separator is bound to the outer periphery with a binding tape 9 made of polypropylene having chemical resistance, etc. It is preferable to suppress misalignment of the positive electrode and the negative electrode wrapped in the separator.

  The total number of positive electrodes and negative electrodes in the electrode group is at least 3, but it is also possible to increase the number (4, 5, 6, 7, 8, etc.). However, if the number of stacked positive and negative electrodes is increased too much, the merit as a flat battery may be reduced. Therefore, it is usually preferable that the number is 13 or less.

  Examples of non-aqueous electrolytes for batteries include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate, butylene carbonate, and vinylene carbonate; chain carbonate esters such as dimethyl carbonate, diethyl carbonate (DEC), and methyl ethyl carbonate. 1,2-dimethoxyethane, diglyme (diethylene glycol methyl ether), triglyme (triethylene glycol dimethyl ether), tetraglyme (tetraethylene glycol dimethyl ether), 1,2-dimethoxyethane, 1,2-diethoxymethane, tetrahydrofuran, etc. It is possible to use an electrolytic solution prepared by dissolving an electrolyte (lithium salt) in a concentration of about 0.3 to 2.0 mol / L in an organic solvent such as ether; That. The above organic solvents may be used alone or in combination of two or more.

Examples of the electrolyte include LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) Lithium salts such as ₂ are mentioned.

  The planar shape of the flat non-aqueous secondary battery of the present invention is not particularly limited, and may be a polygonal shape such as a square (quadrangle) in addition to the circular shape that is the mainstream of conventionally known flat batteries. In addition, the polygon such as a square as the planar shape of the battery in this specification includes a shape in which the corner is cut off and a shape in which the corner is curved. Moreover, the planar shape of the main body part of the positive electrode and the negative electrode may be a shape corresponding to the planar shape of the battery, and may be a substantially circular shape or a polygon such as a rectangle such as a rectangle or a square. In the case of a substantially circular shape, the portion corresponding to the location where the current collecting tab portion of the counter electrode is disposed is cut off as shown in FIGS. 3 and 4 in order to prevent contact with the current collecting tab portion of the counter electrode. It is preferable to use a different shape.

  The flat non-aqueous secondary battery of the present invention can be applied to the same use as a conventionally known flat non-aqueous secondary battery.

The flat non-aqueous secondary battery according to the present invention has, for example, a battery diameter d (when the planar view shape of the battery is not a circle, the planar view area assumes that the planar view shape is a circle. Is suitable for thin batteries with a thickness t (mm) to battery thickness t (mm) of 0.03 to 0.3, which is less than usual. However, high reliability can be secured. Further, the size of the battery of the present invention is not particularly limited, but it can be preferably applied to, for example, a very small size such as an opening area of an insulating gasket of 100 mm ² or less. However, since the battery having a very small opening area of the insulating gasket itself tends to be difficult to produce, the opening area of the insulating gasket according to the battery of the present invention is preferably 20 mm ² or more, for example.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Example 1
<Preparation of positive electrode>
A positive electrode was prepared using LiCoO ₂ as a positive electrode active material, carbon black as a conductive additive, and PVDF as a binder. First, LiCoO ₂ : 93 parts by mass and carbon black: 3 parts by mass were mixed, and the resulting mixture and PVDF: 4 parts by mass were previously dissolved in N-methyl-2-pyrrolidone (NMP). Were mixed to prepare a positive electrode mixture-containing paste. The obtained positive electrode mixture-containing paste was applied to both surfaces of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm by an applicator. When applying the positive electrode mixture-containing paste, the application part and the non-application part were continuously arranged every 5 cm, and the part that was the application part on the front surface was also the application part on the back surface. Subsequently, the applied positive electrode mixture-containing paste was dried to form a positive electrode mixture layer, and then roll-pressed and cut into a predetermined size to obtain a belt-like positive electrode. The positive electrode had a width of 40 mm, and the positive electrode mixture layer forming portion had a thickness of 140 μm.

  The belt-like positive electrode is such that the positive electrode mixture layer forming portion is the main body portion (arc portion diameter 15.1 mm), and the positive electrode mixture layer non-forming portion is the current collecting tab portion (width 3.5 mm). 4 was punched into the shape shown in FIG. 4 to obtain a positive electrode for a battery.

<Integration of battery positive electrode and separator>
A PE microporous membrane separator (thickness 16 μm) having the shape shown in FIG. 8 is disposed on both surfaces of the battery positive electrode, and the portion shown in FIG. 8 is welded by a heat press (temperature 170 ° C., press time 2 seconds). A joining part was formed in a part of the peripheral part of the main part and a part of the peripheral part of the overhanging part related to the two separators, and the battery positive electrode and the separator were integrated. Note that the width of the joint portion relating to the two separators was 0.3 mm for both the main portion and the overhang portion, and the length in the protruding direction from the main portion at the peripheral portion of the overhang portion was 0.5 mm. Of the outer edges of the main parts of the two separators, 90% of the length was used as the joint.

<Production of negative electrode>
A negative electrode was prepared using graphite as the negative electrode active material and PVDF as the binder. The graphite: 94 parts by mass, PVDF: 6 parts by mass, and a binder solution previously dissolved in NMP were mixed to prepare a negative electrode mixture-containing paste. The obtained negative electrode mixture-containing paste was applied to one or both sides of a negative electrode current collector made of a copper foil having a thickness of 10 μm by an applicator. In addition, when applying the negative electrode mixture-containing paste, when the coated part and the non-coated part are continuously applied every 5 cm and are applied to both sides of the current collector, the place where the coated part is the surface is the back side However, it was made to become an application part. Subsequently, the applied negative electrode mixture-containing paste was dried to form a negative electrode mixture layer, and then roll-pressed and cut into a predetermined size to obtain a strip-shaped negative electrode. The negative electrode had a width of 40 mm, and the negative electrode mixture layer forming portion had a thickness of 190 μm when formed on both sides of the current collector and 100 μm when formed on one side of the current collector.

  The strip-shaped negative electrode has the shape shown in FIG. 3 such that the negative electrode mixture layer forming portion is a main body portion (arc portion diameter 16.3 mm) and the negative electrode mixture layer non-forming portion is a current collecting tab portion. The negative electrode for a battery having a negative electrode mixture layer on one side of the current collector and the negative electrode for a battery having a negative electrode mixture layer on both sides of the current collector were obtained. A part of the negative electrode for a battery having the negative electrode mixture layer on one side of the current collector was punched after a PET film having a thickness of 100 μm was attached to the exposed surface of the current collector of the strip-shaped negative electrode. .

<Battery assembly>
Three battery positive electrodes integrated with the separator, two battery negative electrodes with a negative electrode mixture layer formed on both sides of the current collector, and a battery negative electrode with a negative electrode mixture layer formed on one side of the current collector The battery negative electrode with a negative electrode mixture layer formed on one side of the current collector was used as the outermost electrode using two sheets (one of which was a PET film affixed to the exposed surface of the current collector) The battery positive electrode and the battery negative electrode were alternately stacked. And the current collection tab part of each battery positive electrode was collectively welded and integrated. In addition, the current collecting tab portion of each battery negative electrode is forcibly folded over each current collecting tab portion on one of the outermost battery negative electrodes, and these are then welded together. Thus, an electrode group was obtained.

The electrode group was placed in the outer case so that the PET film faced the inner surface of the outer case (positive electrode case), and the integrated current collecting tab portion of each battery positive electrode was welded to the inner surface of the outer case. In addition, an insulating gasket is attached to the sealing case (negative electrode case), and the nonaqueous electrolyte (LiPF ₆₎ is dissolved in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 1: 2 at a concentration of 1.2 mol / l. After adding 90 mg, the outer case containing the electrode group was put on, and the periphery was caulked, the diameter was 20 mm, the thickness was 1.6 mm, and flat non-aqueous water having a structure similar to that shown in FIGS. 6 and 7 A secondary battery was obtained.

  The flat non-aqueous secondary battery is designed to discharge at a current value of 6 mA and a discharge capacity of 30 mAh (the same applies to Comparative Example 1 described later).

Comparative Example 1
Example, except that the current collecting tabs of each negative electrode were welded together at the time of forming the electrode group, and then the integrated current collecting tab part of the negative electrode was folded back on the outermost negative electrode of the electrode group In the same manner as in Example 1, a flat non-aqueous secondary battery was produced.

  When the occurrence state of defective products when 100 flat non-aqueous secondary batteries of Example 1 and Comparative Example 1 were manufactured was investigated, the number of defective products was 0 in the battery of Example 1. On the other hand, the number of batteries in Comparative Example 1 was 5, and it was found that the battery of Example 1 was superior in productivity to the battery of Comparative Example 1.

  In addition, the flat non-aqueous secondary battery of Example 1 was immersed in an epoxy resin, and the epoxy resin was cured, and then the battery was cut at a position where the negative electrode tab portion was present. Thereafter, the cut surface was polished and observed with an optical microscope at a magnification of 40. In either battery, the end of the negative electrode body portion side of the welded portion of the integrated negative electrode current collecting tab portion was observed. The part was located inside the battery from the outermost part on the insulating gasket side in the current collecting tab part of the integrated negative electrode.

  On the other hand, among the flat non-aqueous secondary batteries of Comparative Example 1, those that were not defective were observed in the same manner as in the battery of Example 1, and as a result, all the batteries were integrated. The end of the welded portion of the current collector tab portion of the negative electrode on the side of the main body portion of the negative electrode was located on the outermost side on the insulating gasket side of the current collector tab portion of the integrated negative electrode.

DESCRIPTION OF SYMBOLS 1 Flat type non-aqueous secondary battery 2 Positive electrode case 3 Negative electrode case 4 Insulation gasket 5 Positive electrode 500 Positive electrode main-body part 501 Positive electrode current collection tab part 6, 6A, 6B Negative electrode 600 Negative electrode main-body part 601 Negative electrode current collection tab part 7 Separator 7c Joint 8 Insulating material

Claims (5)

A positive electrode case that also serves as a positive electrode terminal and a negative electrode case that also serves as a negative electrode terminal are formed in a space formed by caulking and sealing via an insulating gasket. A method for producing a flat non-aqueous secondary battery having a non-aqueous electrolyte, and an electrode group having a total number of positive and negative electrodes of 3 or more, which are stacked in parallel to the flat surface of the negative electrode case,
The negative electrode has a main body portion and a current collecting tab portion that protrudes from the main body portion in a plan view and is narrower than the main body portion. The main body portion of the negative electrode includes a current collector. A negative electrode layer containing a negative electrode active material is formed on one side or both sides, and in the current collector tab portion of the negative electrode, the negative electrode layer is not formed on the current collector,
The electrode group has at least two negative electrodes, the outermost electrode on the negative electrode case side in the electrode group is a negative electrode, and the current collecting tab portions of the negative electrode are collected and welded together. The integrated negative electrode current collecting tab portion is folded over the outermost negative electrode on the negative electrode case side of the electrode group,
The end of the negative electrode body portion side of the welded portion of the integrated negative electrode current collector tab portion is located on the inner side of the battery than the outermost portion of the integrated negative electrode current collector tab portion on the insulating gasket side. And
After the positive electrode, the negative electrode, and the separator are stacked, the current collecting tab portions of the negative electrode are forcibly folded and folded on the negative electrode that is the outermost part of the electrode group, and then welded together. And the manufacturing method of the flat type non-aqueous secondary battery characterized by having the process of integrating each current collection tab part of the said negative electrode.   The end of the negative electrode body portion side of the welded portion of the integrated negative electrode current collecting tab portion is 0. 0 in plan view from the outermost portion on the insulating gasket side of the integrated negative electrode current collecting tab portion. The method for producing a flat nonaqueous secondary battery according to claim 1, wherein the flat nonaqueous secondary battery is positioned inside the battery by 3 to 2.6 mm. A positive electrode case that also serves as a positive electrode terminal and a negative electrode case that also serves as a negative electrode terminal are formed in a space formed by caulking and sealing via an insulating gasket. A method for producing a flat non-aqueous secondary battery having a non-aqueous electrolyte, and an electrode group having a total number of positive and negative electrodes of 3 or more, which are stacked in parallel to the flat surface of the negative electrode case,
The positive electrode has a main body portion and a current collecting tab portion that protrudes from the main body portion in a plan view and is narrower than the main body portion. The main body portion of the positive electrode includes a current collector. A positive electrode mixture layer containing a positive electrode active material is formed on one side or both sides, and in the current collector tab portion of the positive electrode, a positive electrode mixture layer is not formed on the current collector,
The electrode group has at least two positive electrodes, and the outermost electrode on the positive electrode case side in the electrode group is a positive electrode, and each current collecting tab portion of the positive electrode is gathered and welded together. The integrated current collecting tab portion of the positive electrode is folded on the outermost positive electrode on the positive electrode case side in the electrode group,
The end of the welded portion of the current collecting tab portion of the integrated positive electrode on the main body side of the positive electrode is located on the inner side of the battery than the outermost portion on the insulating gasket side of the current collecting tab portion of the integrated positive electrode. And
After the positive electrode, the negative electrode, and the separator are stacked, the current collecting tab portions of the positive electrode are forcibly folded and folded on the positive electrode that is the outermost part of the electrode group, and then welded together. A method for producing a flat non-aqueous secondary battery, comprising the step of integrating the current collecting tab portions of the positive electrode.   The end of the welded portion of the integrated positive collector tab portion on the main body side of the positive electrode is 0. 0 in plan view from the outermost portion on the insulating gasket side of the integrated positive collector tab portion. The method for producing a flat non-aqueous secondary battery according to claim 3, wherein the flat non-aqueous secondary battery is positioned inside the battery by 3 to 2.6 mm. The method for producing a flat nonaqueous secondary battery according to claim 1, wherein the total number of positive electrodes and negative electrodes is 13 or less.

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