JP5735096B2 - Non-aqueous secondary battery manufacturing method and non-aqueous secondary battery manufacturing method - Google Patents

Description

  The present invention includes a stacked electrode group, an electrode capable of constituting a non-aqueous secondary battery having a high capacity and good productivity, a method for manufacturing the same, and a non-contact including a stacked electrode group having the electrode. The present invention relates to a water secondary battery.

  For example, in a flat non-aqueous secondary battery, a positive electrode mixture layer or a negative electrode mixture layer is formed on one or both sides of a current collector on a positive electrode and a negative electrode, and a part of the current collector is a positive electrode mixture layer. And exposed without forming a negative electrode mixture layer, and using this as a current collecting tab, the current collecting tabs of each positive electrode and each negative electrode are welded together, and the 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).

  By the way, the electrode of the non-aqueous secondary battery has an electrode mixture layer forming composition prepared by dispersing an electrode active material (positive electrode active material or negative electrode active material) in a solvent on one or both sides of the current collector. Generally, it is manufactured through a process of forming an electrode mixture layer (a positive electrode mixture layer or a negative electrode mixture layer) by coating and drying (for example, Patent Document 2).

  In addition to the above production method, there is also a proposal of a method for producing an electrode for a nonaqueous secondary battery using a screen printing method (Patent Document 3).

JP 2003-142161 A JP 2001-351610 A JP-A-9-330705

  However, in the electrode manufactured by the method described in Patent Document 2, unevenness in thickness tends to occur at the end of the composition for forming an electrode mixture layer applied to a current collector. The thickness of the central portion of the layer in plan view and the thickness of the end portion are different. For example, in the vicinity of the end portion of the electrode mixture layer, the portion closer to the end portion tends to be thinner. In particular, when an electrode is manufactured by providing an exposed portion of a current collector to be a current collecting tab portion by a method in which the composition for forming an electrode mixture layer is not applied, exposure of the current collector to be a current collecting tab portion is performed. The thickness of the electrode mixture layer in the vicinity of the boundary portion with the part tends to be thinner than other portions of the electrode mixture layer.

  For example, in the case of a cylindrical battery or a rectangular battery, an electrode body having a winding structure in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween and wound in a spiral shape is often used. In comparison, in a battery including a stacked electrode group, a reduction in thickness in the vicinity of the boundary portion between the electrode mixture layer and the exposed portion of the current collector greatly affects the capacity.

  Therefore, in increasing the capacity of a non-aqueous secondary battery having a stacked electrode group, the electrode mixture layer related to the electrode used in the battery has a central portion and an end portion in plan view. Development of technology to reduce the variation in thickness is required.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a non-aqueous secondary battery having a high capacity and good productivity, which includes a stacked electrode group, and its manufacture The present invention provides a method and a non-aqueous secondary battery including a stacked electrode group having the electrodes.

  The electrode for a non-aqueous secondary battery of the present invention that can achieve the above object is used for a non-aqueous secondary battery having an electrode group in which a plurality of electrodes are stacked substantially in parallel (including parallel) via a separator. An electrode having a main body portion and a current collecting tab portion protruding from the main body portion in plan view, and the main body portion includes an electrode active material on one or both sides of the current collector A mixture layer is formed, and in the current collector tab portion, an electrode mixture layer is not formed on the current collector and the current collector is exposed, and the current collector of the electrode mixture layer The angle between the side surface at the boundary portion with the exposed portion and the surface in contact with the current collector in the electrode mixture layer is 45 ° or more and less than 90 °.

  The electrode for a non-aqueous secondary battery of the present invention has a mold for forming an electrode mixture layer on the surface of a current collector, and the electrode mixture layer forming composition containing an electrode active material and a solvent is used as the mold. The mold has a step of removing the mold after drying, and the mold has a side surface whose opening area on the current collector side is larger than the opening area on the opposite side of the current collector It can be manufactured by the method for manufacturing an electrode for a non-aqueous secondary battery of the present invention, which is so inclined.

  In the non-aqueous secondary battery of the present invention, the positive electrodes and the negative electrodes are alternately stacked via separators and substantially parallel (including parallel), and the total number of positive electrodes and negative electrodes is three or more. The positive electrode has a current collecting tab portion protruding from the main body portion in plan view, and the main body portion 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, the positive electrode mixture layer is not formed on the current collector, and the current collector is exposed, The negative electrode has a current collecting tab portion protruding from the main body portion in plan view, and the main body portion has a negative electrode agent layer containing a negative electrode active material formed on one side or both sides of the current collector. In the current collecting tab portion, the current collector is exposed without a negative electrode layer formed on the current collector, and the positive electrode and / or the positive electrode layer. It is the negative electrode, and is characterized in that a non-aqueous secondary battery electrode of the present invention.

  According to the present invention, an electrode that includes a stacked electrode group and can constitute a non-aqueous secondary battery with high capacity and good productivity, a manufacturing method thereof, and a stacked electrode group having the electrode are provided. A non-aqueous secondary battery can be provided. That is, the nonaqueous secondary battery of the present invention has a high capacity and good productivity.

It is a longitudinal section showing typically an example of the nonaqueous secondary battery of the present invention. It is a top view which represents typically an example of the electrode for nonaqueous secondary batteries of this invention which is a positive electrode. It is a top view which represents typically an example of the electrode for nonaqueous secondary batteries of this invention which is a negative electrode. It is a principal part enlarged view of an example of the longitudinal cross-section of the electrode for non-aqueous secondary batteries of FIG. It is a principal part enlarged view of an example of the longitudinal cross-section of the electrode for non-aqueous secondary batteries of FIG. It is a principal part enlarged view of the other example of the longitudinal cross-section of the electrode for nonaqueous secondary batteries of FIG. It is a principal part enlarged view of the other example of the longitudinal cross-section of the electrode for non-aqueous secondary batteries of FIG. It is explanatory drawing of the manufacturing method of the electrode for non-aqueous secondary batteries of this invention. It is a longitudinal cross-sectional view which represents typically the other example of the non-aqueous secondary battery of this invention. It is a principal part cross-sectional enlarged view of the non-aqueous secondary battery of FIG. It is a top view which represents typically an example of the separator which concerns on the nonaqueous secondary battery of this invention.

  FIG. 1 is a longitudinal sectional view schematically showing an example of the nonaqueous secondary battery of the present invention. A non-aqueous secondary battery 1 shown in FIG. 1 is a flat non-aqueous secondary battery, and a plurality of positive electrodes 5 and a plurality of negative electrodes 6 (6A, 6B) are connected to each other through a separator 7 so that the flat surface of the battery is flat. A space formed by the exterior case 2, the sealing case 3, and the insulating gasket 4, in which a stacked electrode group laminated so as to be substantially parallel (including parallel) to the surface and a non-aqueous electrolyte (not shown) ( It is housed in a sealed space. The sealing case 3 is fitted to the opening of the outer case 2 via an insulating gasket 4, and the opening end of the outer case 2 is tightened inward, whereby the insulating gasket 4 contacts the sealing case 3. Thereby, the opening part of the exterior case 2 is sealed, and the inside of the battery has a sealed structure. In the stacked electrode group, the stacked surfaces of the positive electrode 5, the negative electrode 6, and the separator 7 are substantially parallel (including parallel) to the flat surfaces of the battery, that is, the flat surfaces of the outer case 2 and the sealing case 3. The outer case 2, the sealing case 3, and the insulating gasket 4 are housed in the outer case. The outer case 2 and the sealing case 3 are made of a metal such as stainless steel, and the insulating gasket 4 is made of an insulating resin such as nylon.

  Each of the positive electrode 5 and the negative electrode 6 of the flat nonaqueous secondary battery 1 shown in FIG. 1 is an electrode for a nonaqueous secondary battery of the present invention.

  FIG. 2 schematically shows a plan view of the positive electrode 5. The positive electrode 5 includes a main body portion 5a and a current collecting tab portion 5b protruding from the main body portion 5a in plan view. As shown in FIG. 2, the current collecting tab portion 5b usually has a width (length in the vertical direction in FIG. 2) narrower than that of the main body portion 5a.

  As shown in FIGS. 1 and 2, the main body portion 5 a of the positive electrode 5 has a positive electrode mixture layer 51 formed on both surfaces of a current collector 52. In the current collecting tab portion 5 b of the positive electrode 5, the positive electrode mixture layer 51 is not formed on the surface of the current collector 52, and the current collector 52 is exposed. In the electrode group according to the battery shown in FIG. 1, the outermost electrodes (upper and lower ends in the figure) are all negative electrodes (negative electrode 6B), and all of the positive electrodes 5 are on both sides (both sides) via the separator 7. Since it faces the negative electrode 6, it has the positive electrode mixture layer 51 on both surfaces of the current collector 52. For example, when the outermost electrode of the electrode group is a positive electrode, the outermost positive electrode May have a structure having a positive electrode mixture layer only on one side of the current collector (the surface inside the battery).

  FIG. 3 schematically shows a plan view of the negative electrode 6. The negative electrode 6 has a main body portion 6a and a current collecting tab portion 6b protruding from the main body portion 6a in plan view. As shown in FIG. 3, the current collecting tab portion 6b usually has a width (length in the vertical direction in FIG. 3) narrower than that of the main body portion 6a.

  As shown in FIGS. 1 and 3, the main body portion 6 a of the negative electrode 6 </ b> B located at the outermost part of the electrode group has a negative electrode mixture layer 61 formed only on one surface (surface inside the battery) of the current collector 62. The negative electrode mixture layer 61 is formed on both surfaces of the current collector 62 in the main body portion 6a of the negative electrode 6A other than that. Further, in the current collecting tab portion 6b of the negative electrodes 6A and 6B, the negative electrode mixture layer 61 is not formed on the surface of the current collector 62, and the current collector is exposed.

  FIG. 4 is an enlarged view schematically showing the main part of the longitudinal section of the positive electrode 5 shown in FIG. As shown in FIG. 4, the positive electrode 5 according to the battery shown in FIG. 1 has side surfaces (511a and 511b in FIG. 4) at the boundary portion of the positive electrode mixture layer 51 with the exposed portion of the current collector 52. An angle (angles A and A ′ in FIG. 4) between the surfaces in contact with the current collector 52 in the positive electrode mixture layer 51 (512a and 512b in FIG. 4) is 45 ° or more and less than 90 °.

  FIG. 5 is an enlarged view schematically showing the main part of the longitudinal section of the negative electrode 6 shown in FIG. As shown in FIG. 5, the negative electrode 6 according to the battery shown in FIG. 1 has side surfaces (611 a and 611 b in FIG. 5) at the boundary portion between the negative electrode mixture layer 61 and the exposed portion of the current collector 62. The angles (angles B and B ′ in FIG. 5) between the surfaces in contact with the current collector 62 in the positive electrode mixture layer 61 (612a and 612b in FIG. 5) are 45 ° or more and less than 90 °.

  As shown in FIGS. 2 to 5, the electrode for a non-aqueous secondary battery of the present invention has a main body portion and a current collecting tab portion protruding from the main body portion in plan view. The electrode mixture layer containing the electrode active material (positive electrode mixture layer or negative electrode mixture layer) is formed on one side or both sides of the current collector, and the current collector tab portion has the electrode mixture layer on the current collector. The current collector is not formed and the angle between the side surface of the electrode mixture layer at the boundary with the exposed portion of the current collector and the surface in contact with the current collector in the electrode mixture layer Is 45 ° or more and less than 90 °.

  As described above, when an electrode is produced through a step of applying a composition for forming an electrode mixture layer prepared by dispersing a constituent material of an electrode mixture layer such as an electrode active material in a solvent to a current collector, When the electrode mixture layer is not formed on a part of the electric conductor and is an exposed portion, the side surface of the electrode mixture layer at the boundary portion with the exposed portion of the current collector is gently inclined. The angles A and A ′ in FIG. 4 and the angles B and B ′ in FIG. 5 tend to be very small.

  For example, in the case of a relatively long band like an electrode used for a battery having a wound electrode group, the electrode mixture layer on the side surface portion at the boundary portion with the exposed portion of the current collector Therefore, the influence on the battery capacity due to the gentle inclination of the side surface is extremely small. However, when the electrode group is formed by laminating a total of three or more positive electrodes and negative electrodes as in the non-aqueous secondary battery of the present invention, each electrode has a boundary with the exposed portion of the current collector. Since the ratio of the side surface portion in the portion to the entire electrode mixture layer is relatively large, the battery capacity is reduced.

  Therefore, in the electrode for a non-aqueous secondary battery of the present invention, an electrode mixture layer (in the case where the electrode mixture layer is provided only on one side of the current collector, the electrode mixture layer is formed on both sides of the current collector. In the case of having a layer, both of these electrode mixture layers.The electrode mixture layer is the same unless otherwise specified)), the side surface at the boundary portion with the exposed portion of the current collector, and the electrode mixture layer The angle between the surface in contact with the current collector is set to 45 ° or more, preferably 60 ° or more, so as to suppress a decrease in battery capacity due to the shape of the side surface as much as possible.

  As will be described later, the electrode for a non-aqueous secondary battery of the present invention has a mold placed on the surface of the current collector, filled with a composition for forming an electrode mixture layer in the holes of the mold, and dried. Preferably, the angle between the side surface of the electrode mixture layer at the boundary portion with the exposed portion of the current collector and the surface in contact with the current collector in the electrode mixture layer is 90. When the angle is less than 0 °, preferably not more than 86 °, it is possible to increase the production of the electrode particularly when manufacturing by the above method.

  In the electrode for a nonaqueous secondary battery of the present invention, of the side surfaces of the electrode mixture layer, the side surface at the boundary portion with the exposed portion of the current collector and the surface in contact with the current collector of the electrode mixture layer And the angle between the other part of the side surface of the electrode mixture layer and the surface in contact with the current collector of the electrode mixture layer may be 90 °, for example. Good. However, from the viewpoint of facilitating the production of the electrode, as shown in FIG. 1, the angle between the entire side surface of the electrode mixture layer and the surface in contact with the current collector of the electrode mixture layer is as described above. More preferably, the value is 45 ° or more, preferably 60 ° or more and less than 90 °, preferably 86 ° or less.

  Further, as shown in FIG. 4, the positive electrode 5 according to the battery shown in FIG. 1 has a positive electrode mixture layer 51 formed on one surface of the current collector 52 (for example, the upper positive electrode mixture layer 51 in the figure). Of the current collector 52 in the positive electrode mixture layer 51 (for example, the lower positive electrode mixture layer 51 in the figure) formed on the other surface of the current collector 52. The positional deviation from the boundary with the exposed portion (the length a in the figure) is preferably 0.1 mm or less, and more preferably 0.05 mm or less.

  Further, among the negative electrodes related to the battery shown in FIG. 1, the negative electrode 6A having the negative electrode mixture layers on both sides of the current collector is formed of the negative electrode composite formed on one side of the current collector 62 as shown in FIG. The negative electrode mixture layer 61 (for example, the figure) formed in the boundary part with the exposed part of the collector 62 in the agent layer 61 (for example, upper negative electrode mixture layer 61 in the figure) and the other surface of the current collector 62 In the middle and lower negative electrode mixture layer 61), the positional deviation (the length of b in the figure) from the boundary with the exposed portion of the current collector 62 is preferably 0.1 mm or less, and 0.05 mm or less. It is more preferable that

  That is, in the electrode for a non-aqueous secondary battery of the present invention, when the electrode mixture layer is provided on both sides of the current collector, the exposed portion of the current collector in the electrode mixture layer formed on one side of the current collector The positional deviation between the boundary portion and the boundary portion between the exposed portion of the current collector in the electrode mixture layer formed on the other surface of the current collector is preferably 0.1 mm or less, and 0.05 mm or less. More preferably.

  An electrode mixture layer is formed on the surface of the current collector through a step of applying a composition for forming an electrode mixture layer prepared by dispersing constituent materials of the electrode mixture layer such as an electrode active material in a solvent to the current collector. For example, in order to provide an exposed portion of a current collector that becomes a current collecting tab portion, a method of intermittently applying an electrode mixture layer to a long current collector is often employed. . However, in such a method, when the electrode mixture layer is formed on both sides of the current collector, the boundary portion between the electrode mixture layer and the exposed portion of the current collector is formed on one side and the other side of the current collector. It is difficult to align the positions without deviation.

  In the both electrode mixture layers formed on both surfaces of the current collectors related to the electrodes, when the positional deviation increases, for example, the volume of the electrode mixture layer on one side of the current collector is reduced, which is assumed when designing the battery. There is a possibility that the amount of electrode active material cannot be introduced, or the facing area between the positive electrode and the negative electrode becomes smaller than the area assumed at the time of battery design, resulting in a decrease in battery capacity. Further, if the positional deviation becomes too large, the battery may not be used.

  For example, in the case of a relatively long band like an electrode used for a battery having a wound electrode group, the exposed portion of the current collector in the electrode mixture layer on one side of the current collector Even if the position of the boundary portion and the boundary portion between the exposed portion of the current collector in the electrode mixture layer on the other surface of the current collector is slightly deviated, the influence on the battery capacity is extremely small. However, in the case of having an electrode group formed by laminating a total of three or more positive electrodes and negative electrodes as in the non-aqueous secondary battery of the present invention, the size of each electrode is an electrode group having a wound structure. Since it is smaller than a strip-shaped electrode as used, the influence on the battery capacity due to the positional deviation is greater than that of a battery having a wound electrode group.

  Therefore, in the electrode for a non-aqueous secondary battery of the present invention, the electrode mixture layer formed on one side of the current collector is formed on the boundary between the exposed portion of the current collector and on the other side of the current collector. The positional deviation of the electrode mixture layer from the boundary portion with the exposed portion of the current collector is preferably 0.1 mm or less, and more preferably 0.05 mm or less. . As a result, it is possible to suppress a decrease in the battery capacity due to the above-described displacement as much as possible, and to manufacture a higher capacity non-aqueous secondary battery with better productivity.

  FIG. 6 is an enlarged view schematically showing the main part of the longitudinal section of the positive electrode 5 where the positional deviation is 0 mm. FIG. 7 shows the negative electrode 6 (where the positional deviation is 0 mm. The enlarged view which represents typically the principal part of the longitudinal cross-section of the negative electrode 6A) which has a negative mix layer on both surfaces of a collector is shown. As shown in FIG. 6 and FIG. 7, in the electrode for a non-aqueous secondary battery of the present invention, a boundary portion with the exposed portion of the current collector in the electrode mixture layer formed on one surface of the current collector, It is particularly preferable that the positional deviation between the electrode mixture layer formed on the other surface of the current collector and the boundary portion with the exposed portion of the current collector is 0 mm.

  The electrode for a non-aqueous secondary battery of the present invention comprises, for example, an electrode mixture layer forming composition prepared by dispersing a constituent material of an electrode mixture layer such as an electrode active material in a solvent, Although it can manufacture through the process of apply | coating to both surfaces, drying, and also performing a press process, manufacturing with the manufacturing method of this invention is preferable.

  In the method for producing an electrode for a non-aqueous secondary battery according to the present invention, when a composition for forming an electrode mixture layer is applied to the current collector surface, a mold for forming the electrode mixture layer is disposed on the surface of the current collector. The composition for forming an electrode mixture layer is filled in the holes of the mold, and then dried to form an electrode mixture layer (positive electrode mixture layer 51 or negative electrode mixture layer 61), and then the mold. A mold having a hole whose side surface is inclined so that the opening area on the current collector side is larger than the opening area on the opposite side of the current collector. use.

  According to the screen printing method, the electrode mixture layer can be formed by drying while suppressing the flow of the electrode mixture layer forming composition by the mold. The angle between the side surface in the boundary portion with the exposed portion with the body, the other side surface portion, and the surface in contact with the current collector of the electrode mixture layer is preferably 45 ° or more, preferably 60 ° or more. Can be adjusted. Further, in the case of the screen printing method, when the planar electrode shown in FIGS. 2 and 3 is manufactured, for example, compared with a case where a method of punching a strip electrode manufactured by the conventional manufacturing method as described above is employed. Thus, the portion to be discarded can be greatly reduced, so that the productivity of the electrode, and thus the productivity of the non-aqueous secondary battery having this electrode can be increased.

  In addition, when a mold having the above-described holes is used, the mold can be easily removed after the composition for forming an electrode mixture layer is filled in the holes and dried. Productivity can be increased. In addition, by using the type | mold which has the said hole, the side surface in the boundary part of an electrode mixture layer with an exposed part with a collector, another side part, and the collector of an electrode mixture layer are contact | connected. The angle between the surfaces is less than 90 °, preferably 86 ° or less.

  When manufacturing an electrode having electrode mixture layers on both sides of the current collector, an ordinary screen printing method forms an electrode mixture layer on one side of the current collector, and then on the other side of the current collector. Even if an electrode mixture layer is to be formed, the electrode mixture layer is formed discontinuously on one side of the current collector, resulting in uneven thickness of the current collector and electrode mixture layer. It becomes difficult to uniformly apply the composition for forming an electrode mixture layer on the other surface of the current collector, and an electrode with good quality cannot be produced.

  Therefore, in the case of an electrode having electrode mixture layers on both sides of the current collector, first, the mold is disposed on one side of the current collector, and the composition for forming the electrode mixture layer is filled in the holes. Step (I) to be dried and the same type as the above is placed on the other side of the current collector without removing the mold used in the step (I), Step (II) of filling the electrode mixture layer forming composition in the hole (in the hole of the mold disposed on the other surface of the current collector) and drying, and after the step (II), It is preferable to manufacture through the step (III) of removing the molds arranged on both surfaces (the one surface and the other surface). In this case, when the electrode mixture layer forming composition is applied to the other surface of the current collector, the integrated material of the current collector and the electrode mixture layer formed on the one surface is not suitable. It is possible to avoid the problem of thickness unevenness due to the continuously formed electrode mixture layer and to produce an electrode of good quality.

  Further, from a strip-like electrode produced by intermittently applying a composition for forming an electrode mixture layer to a strip-shaped current collector, for example, in the planar shape shown in FIG. 2 or FIG. When manufacturing an electrode having a layer, it is not easy to accurately match the position of the end portion of the electrode mixture layer on one side of the current collector with the end portion of the electrode mixture layer on the other side. Furthermore, it is difficult to reduce the positional deviation between both electrode mixture layers.

  However, if it is a manufacturing method which has the said process (I) from the said process (I), for example, the type | mold for electrode mixture layer formation of the single side | surface of a collector, and the electrode mixture layer of the other side of a collector Since the positioning with the forming mold can be performed mechanically (for example, pinned), the positional deviation of both electrode mixture layers can be reduced to the above value. . Therefore, by adopting the manufacturing method having the steps (I) to (III), the productivity of the electrode having the electrode mixture layer on both sides of the current collector, and thus the non-aqueous two having this electrode. The productivity of the secondary battery can be further increased, and the capacity reduction of the battery can be further suppressed.

  Each process in the case of manufacturing the electrode which has an electrode mixture layer on both surfaces of a collector is demonstrated more concretely using FIG. In step (I), first, the electrode mixture layer forming mold 100a is disposed on one surface of the current collector 52 (or current collector 62) [FIG. 8 (a)]. Then, the hole 101 of the mold 100a is filled with the electrode mixture layer forming composition and dried [FIG. 8 (b)]. By this step (I), an electrode mixture layer (positive electrode mixture layer 51 or negative electrode mixture layer 61) is formed on one surface of the current collector (positive electrode current collector 52 or negative electrode current collector 62).

  Subsequently, in the step (II), the mold 100a used in the step (I) is disposed on one side of the current collector 52 (or current collector 62), and the current collector 52 (or current collector) is disposed. 62) On the other surface [lower surface in FIG. 6], a mold 100b for forming an electrode mixture layer is disposed [FIG. 8 (c)]. Then, the electrode mixture layer forming composition is filled in the hole 101 of the mold 100b and dried [FIG. 8 (d)]. By this step (II), an electrode mixture layer (positive electrode mixture layer 51 or negative electrode mixture layer 61) is also formed on the other surface of the current collector (positive electrode current collector 52 or negative electrode current collector 62).

  Subsequently, in step (III), after the completion of step (II), the molds 100a and 100b disposed on one side and the other side of the current collector 52 and the current collector 62 are removed [FIG. 8 (e)].

  The inclination angle of the hole in the electrode mixture layer forming mold used in the method of the present invention [the angle between the surface of the mold with the smaller opening area in the hole and the inner wall of the hole. The angle C in FIG. same as below. ] From the viewpoint of easily adjusting the angle between the side surface of the electrode mixture layer at the boundary portion with the exposed portion of the current collector and the surface of the electrode mixture layer in contact with the current collector to the above value. 45 ° or more, preferably 60 ° or more, preferably less than 90 °, more preferably 86 ° or less.

  The electrode after forming the electrode mixture layer and removing the mold is preferably subjected to press treatment to adjust the thickness and density of the electrode mixture layer. Then, an exposed portion of the current collector of the electrode in which the electrode mixture layer is discontinuously formed on one side or both sides of the current collector is cut to obtain a desired planar shape (for example, the planar shape shown in FIG. 2 or FIG. 3). ) Electrode can be obtained.

  When the nonaqueous secondary battery electrode of the present invention is a positive electrode, the electrode mixture layer, that is, the positive electrode mixture layer is a layer containing a positive electrode active material, a conductive additive, a binder and the like.

Examples of the positive electrode active material include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O ₂ , Li _x Co _y M _1-y O ₂ , and Li _x Ni _1-1. like _{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 lithium-transition metal composite oxides such as (However, in each of the lithium transition metal composite oxides, M is at least one metal element selected from the group consisting of Mg, Mn, Fe, Co, Ni, Cu, Zn, Al, and Cr; ≦ x ≦ 1.1, 0 <y <1.0, 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 which concerns on a positive mix layer, carbon black, scale-like graphite, ketjen black, acetylene black, fibrous carbon etc. are mentioned, for example. Furthermore, examples of the binder related to the positive electrode mixture layer include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), carboxymethyl cellulose, and styrene butadiene rubber.

  When the nonaqueous secondary battery electrode of the present invention is a positive electrode, the positive electrode mixture layer forming composition for forming the positive electrode mixture layer includes, for example, a positive electrode active material, a conductive additive, a binder, and the like. A paste or slurry prepared by dispersing in water or an organic solvent can be used.

  The composition of the positive electrode mixture layer is, for example, 75% to 90% by mass of the positive electrode active material, 5% to 20% by mass of the conductive additive, and 3% to 15% of the binder in 100% by mass of all the components of the positive electrode mixture layer. % Is preferable. Moreover, it is preferable that the thickness of a positive mix layer is 30-200 micrometers per single side | surface of a collector, for example.

  As the current collector for the positive electrode, a metal foil composed of aluminum or an aluminum alloy, an expanded metal, a plain woven wire mesh, or the like is preferable. In addition, by reducing the total thickness of the positive electrode and increasing the number of stacked positive and negative electrodes in the battery, a positive electrode mixture layer and a negative electrode agent layer (a negative electrode active material that is not composed of a negative electrode mixture layer and a negative electrode mixture) From the viewpoint of enhancing the load characteristics of the battery by increasing the facing area with respect to the negative electrode layer not composed of the negative electrode mixture, which will be described later), the current collector is made of metal. It is preferable to use a foil. Moreover, it is preferable that the thickness of a collector is 8-20 micrometers, for example.

  When the electrode for nonaqueous secondary batteries of the present invention is a negative electrode, the electrode mixture layer, that is, the negative electrode mixture layer is a layer containing a negative electrode active material, a binder, and the like.

  Examples of the negative electrode active material include lithium, lithium alloy, a carbon material capable of occluding and releasing lithium ions, and lithium titanate.

  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.

  The binder which concerns on the negative mix layer can use the various binders illustrated previously as what can be used for a positive mix layer.

  Moreover, a conductive support agent can also be contained in the negative mix layer as needed. As the conductive auxiliary agent related to the negative electrode mixture layer, various conductive auxiliary agents exemplified above as those that can be used for the positive electrode mixture layer can be used.

  When the nonaqueous secondary battery electrode of the present invention is a negative electrode, the negative electrode mixture layer forming composition for forming the negative electrode mixture layer includes, for example, a negative electrode active material and a binder, and further if necessary. A paste or slurry prepared by dispersing a conductive additive or the like in water or an organic solvent can be used.

  The composition of the negative electrode mixture layer when a carbon material is used as the negative electrode active material is, for example, 80 to 95% by mass of the carbon material and 3 to 15% by mass of the binder in 100% by mass of all the constituent components of the negative electrode mixture layer. In addition, when a conductive auxiliary is used in combination, the conductive auxiliary is preferably 5 to 20% by mass. On the other hand, the composition of the negative electrode mixture layer when lithium titanate is used as the negative electrode active material is, for example, 75 to 90% by mass of lithium titanate and 3% of binder in 100% by mass of all the components of the negative electrode mixture layer. It is preferable to set it as -15 mass%, and when using a conductive support agent together, it is preferable to make a conductive support agent into 5-20 mass%. The thickness of the negative electrode mixture layer in the negative electrode is preferably, for example, 40 to 200 μm per one side of the current collector.

  As the current collector of the negative electrode, a metal foil composed of copper or a copper alloy, an expanded metal, a plain woven wire mesh, or the like is preferable. In addition, by reducing the total thickness of the negative electrode and increasing the number of stacked positive and negative electrodes in the battery, the opposing area between the positive electrode mixture layer and the negative electrode agent layer (including the negative electrode mixture layer) is increased. From the viewpoint of enhancing the load characteristics, 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.

  In the non-aqueous secondary battery of the present invention, at least one of the positive electrode and the negative electrode may be the electrode for the non-aqueous secondary battery of the present invention, but as shown in FIG. A non-aqueous secondary battery electrode is preferred.

  In the nonaqueous secondary battery of the present invention, when either one of the positive electrode and the negative electrode is the electrode for the nonaqueous secondary battery of the present invention, the other electrode includes, for example, an electrode mixture layer, a current collector An electrode having an angle between the side surface at the boundary portion with the exposed portion and the surface in contact with the current collector in the electrode mixture layer may be 90 ° or less than 45 °. Further, when the positive electrode is the electrode for a non-aqueous secondary battery of the present invention, a negative electrode layer made of a foil of lithium or lithium alloy as a negative electrode active material is pressed on one or both sides of the current collector. An electrode configured as described above can also be used.

  The non-aqueous secondary battery of the present invention has an exterior body composed of an exterior case, a sealing case, and an insulating gasket (that is, an exterior body composed of an exterior case and a sealing case that are caulked and sealed via an insulation gasket). It is possible to take the form of a flat type non-aqueous secondary battery having a laminate-type non-aqueous secondary battery having a laminate film outer package made of a metal laminate film. 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 referred to in this specification includes both coin-type batteries and button-type batteries.

  The details of the non-aqueous secondary battery of the present invention will be described below with reference to the drawings, centering on a flat non-aqueous secondary battery which is a typical embodiment of the non-aqueous secondary battery of the present invention.

  In the battery 1 shown in FIG. 1, the current collecting tab portions 5b of all the positive electrodes 5 constituting the electrode group are collected, and these are welded to the inner surface of the outer case 2 or directly contacted without being welded. So that they are electrically connected. That is, in the battery shown in FIG. 1, the outer case also serves as the positive electrode terminal. The current collecting tab portions 5b of the collected positive electrodes 5 may or may not be welded to each other, but the collected current collecting tab portions 5b are separated at the time of manufacturing the battery. It is preferable that the current collecting tab portions 5b are welded to each other in that they can be suppressed.

  In the battery 1 shown in FIG. 1, as described above, the outermost portions (upper and lower ends) of the electrode group become the negative electrodes 6B and 6B having the negative electrode mixture layer only on one side (surface inside the battery) of the current collector. The exposed surface of the current collector of the negative electrode 6B on the lower side in the drawing in the electrode group is welded to the inner surface of the sealing case 3 or directly connected without welding. . That is, in the battery shown in FIG. 1, the sealing case 3 also serves as a negative electrode terminal.

  And all the negative electrodes 6 which the electrode group has (the negative electrode 6A in which the negative electrode mixture layer 61 is formed on both surfaces of the current collector 62 and the negative electrode 6B in which the negative electrode mixture layer 61 is formed on one surface of the current collector 62) are The current collector tab portions 6b are electrically connected to each other. In addition, the connection of the current collection tab part 6b of each negative electrode 6 can be performed by welding, for example.

  As described above, in the nonaqueous secondary battery of the present invention, one or both of the outermost electrodes of the electrode group can be used as a positive electrode. When the non-aqueous secondary battery of the present invention is a flat non-aqueous secondary battery, the current collector is exposed without forming a positive electrode mixture layer on one surface of the positive electrode at the outermost part of the electrode group. The exposed surface of the electric body and the inner surface of a battery case (for example, an exterior case) that also serves as a positive electrode terminal may be electrically connected by welding or directly contacting without welding.

  Further, in the battery 1 shown in FIG. 1, for the purpose of insulating the negative electrode 6B located at the uppermost part of the electrode group and the outer case 2, a film made of a heat-fusible resin such as polyolefin is interposed therebetween. Alternatively, an insulating layer 8 made of an adhesive tape or the like having a base material of polyethylene terephthalate (PET) or polyimide and having an adhesive layer on both sides is disposed. The thickness of the insulating layer is preferably 50 to 150 μm, for example.

  In the nonaqueous secondary 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.

  9 and 10 schematically show other examples of the nonaqueous secondary battery of the present invention. The battery 1 shown in FIG. 9 and FIG. 10 is a flat non-aqueous secondary battery having an electrode group formed by forming a joint portion at the periphery of two separators 7 and 7 arranged on both surfaces of the positive electrode 5. is there. FIG. 9 is a longitudinal sectional view showing a cross section of the battery case (the outer case 2 and the sealing case 3) and the insulating gasket 4 part of the battery. FIG. 10 is an enlarged view of the main part of FIG. It is a cross section.

  FIG. 11 schematically shows a plan view of a separator in which a joining portion is formed on a part of the peripheral edge. In FIG. 11, 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 below the separator 7 is indicated by a dotted line. A current collecting tab portion 6b related 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 related to the electrode group is indicated by a two-dot chain line. Further, the positive electrode 5 shown in FIG. 11 has both sides (both sides) opposed to the negative electrode in the electrode group. Although not shown in FIG. 11, when the electrode group is used, the upper side of the separator 7 (in the drawing) In the forward direction), at least a negative electrode is arranged.

  The separator 7 shown in FIG. 11 is joined to another separator disposed on the lower side (depth direction in the drawing) via the positive electrode 5 (indicated by a dotted line in the drawing), and a joint 7c (see 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. 11 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. 11, 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. 11, the peripheral part which concerns 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 a battery is manufactured 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. It is possible to prevent the occurrence of problems due to residual air in the interior (problems such as non-uniform reaction during power generation and reduced capacity improvement effect).

  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 1-10 seconds.

  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 part formed by welding a part of each other, the shape shown in FIG. 9 is preferable. However, even when the joint part 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.

  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 FIGS. 1, 9, and 10. At this time, the current collecting tab portion of each positive electrode is a plane of the electrode group. It is preferable that they are arranged so as to face the same direction as viewed, and the current collecting tab portions of the respective negative electrodes are arranged so as to face the same direction when seen in a 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, And from the viewpoint of making the production of the battery better, as shown in FIG. 11, the current collecting tab portion 5b of each positive electrode and the current collecting tab portion 6b of each negative electrode face each other in a plan view of the electrode group. More preferably, it is arranged at a position where

  In addition, as shown in FIG. 11, 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 or the like having chemical resistance. It is preferable to suppress misalignment of the (positive electrode, negative electrode and 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 40 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 non-aqueous electrolyte may be used in the non-aqueous secondary battery of the present invention in the form of a gel (gel electrolyte) by adding a known gelling agent such as a polymer.

  There is no restriction | limiting in particular in the planar shape of the non-aqueous secondary battery of this invention. For example, in the case where the non-aqueous secondary battery of the present invention is a flat non-aqueous secondary battery having an exterior body composed of an exterior case, a sealing case, and an insulating gasket, a conventionally known flat battery In addition to a circular shape, which is the mainstream, a polygonal shape such as a square (quadrangle) can be used. Further, when the non-aqueous secondary battery of the present invention is a laminated non-aqueous secondary battery having a laminate film outer package, a planar shape required according to the application (polygonal shape such as a circle or a quadrangle) It can be.

  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. Further, the planar shape of the main body of the positive electrode and the negative electrode (including the flat non-aqueous secondary battery electrode of the present invention) may be a shape corresponding to the planar shape of the battery, and may be substantially circular, rectangular or square. For example, 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 in contact with the current collecting tab portion of the counter electrode. In order to prevent this, it is preferable to use a cut-off shape as shown in FIGS.

  1, 9, and 10 show a flat non-aqueous secondary battery in which the outer case also serves as the positive electrode terminal and the sealing case also serves as the negative electrode terminal. However, the non-aqueous secondary battery of the present invention is limited to this. Instead, the outer case may also serve as the negative electrode terminal, and the sealing case may also serve as the positive terminal if necessary.

  The present invention has been described so far with reference to FIGS. 1 to 11, but these drawings are for facilitating the understanding of the present invention. The size ratio is not always accurate.

The non-aqueous secondary battery of the present invention is not particularly limited in size, but in the case of a flat non-aqueous secondary battery having an exterior body composed of an exterior case, a sealing case, and an insulation gasket, for example, insulation When the opening area of the gasket is a very small size such as 100 mm ² or less, the influence of the shape of the end of the electrode mixture layer and the displacement of the electrode mixture layer on both sides of the current collector on the battery capacity is particularly large Therefore, the effect produced by the present invention becomes more remarkable. However, since the battery having a very small opening area of the insulating gasket tends to be difficult to produce, the opening area of the insulating gasket according to the nonaqueous secondary battery of the present invention is, for example, 20 mm ² or more. Is preferred.

  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 layer forming paste.

  A mold having a hole with an inclination angle of 85 ° was placed on one side of an aluminum foil having a thickness of 15 μm serving as a positive electrode current collector so that the surface with the wider opening area of the hole was on the aluminum foil side. The positive electrode mixture layer forming paste placed on the mold was filled in the holes while being scraped with a squeegee and dried. Subsequently, a mold having the same shape as described above was placed on the other surface of the aluminum foil, and the positive electrode mixture layer forming paste was filled in the holes in the same manner as in the case of the one surface of the aluminum foil, followed by drying. After that, the integrated product of the aluminum foil and the positive electrode mixture layer from which the mold has been removed is roll-pressed, and subsequently, in the shape shown in FIG. 2, the diameter of the arc portion of the main body portion having the positive electrode mixture layer is 6 mm, A portion of the aluminum foil was punched out so that the width of the current collecting tab portion composed of the exposed portion of the current collector (aluminum foil) was 3 mm to obtain a positive electrode. In the positive electrode obtained, the thickness of the positive electrode mixture layer was 70 μm per side of the current collector, the angles A and A ′ shown in FIG. 4 were 85 °, and the length of a shown in FIG. It was 05 mm.

<Integration of positive electrode and separator>
A PE microporous membrane separator (thickness 16 μm) having the shape shown in FIG. 11 is disposed on both surfaces of the positive electrode, and the portions shown in FIG. 11 are welded by a hot press (temperature 170 ° C., press time 2 seconds). A joining part was formed in a part of a peripheral part of a main part concerning a sheet of separator, and a part of a peripheral part of an overhanging part, and a positive electrode and a separator were unified. 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 1.0 mm. Of the outer edges of the main parts of the two separators, 92% 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 negative electrode mixture layer forming paste was prepared by mixing 94 parts by mass of graphite, 6 parts by mass of PVDF, and a binder solution previously dissolved in NMP.

  A mold having a hole with an inclination angle of 85 ° was placed on one side of a 10 μm-thick copper foil serving as a negative electrode current collector so that the side with the wider opening area of the hole was the copper foil side. Then, using the negative electrode mixture layer forming paste, a negative electrode mixture layer is formed on the surface of the copper foil in the same manner as in the case of the positive electrode. In the shape shown in FIG. 3, the diameter of the arc portion of the main body portion having the negative electrode mixture layer is 8 mm, and the width of the current collecting tab portion formed by the exposed portion of the current collector (copper foil) is A negative electrode of 3 mm was obtained.

  In addition, about the negative electrode, what has a negative mix layer on only one side of a collector, and what has a negative mix layer on both sides of a current collector were produced. A part of the negative electrode 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. The obtained negative electrode has a negative electrode mixture layer having a negative electrode mixture layer only on one side of the current collector and a negative electrode mixture layer only on both sides of the current collector. It was 100 μm per one side, and the angle of B (negative electrode having a negative electrode mixture layer on one side and negative electrode having both sides) and B ′ (negative electrode having a negative electrode mixture layer on both sides) shown in FIG. 5 was 85 °. Moreover, the negative electrode which has a negative mix layer on both surfaces of a collector was 0.05 mm in length of b shown in FIG.

<Battery assembly>
14 positive electrodes integrated with the separator, 15 negative electrodes with a negative electrode mixture layer formed on both sides of the current collector, and two negative electrodes with a negative electrode mixture layer formed on one side of the current collector (of which 1 The sheet is made by adhering a PET film to the exposed surface of the current collector), and the positive electrode and the negative electrode are formed so that the negative electrode having the negative electrode mixture layer formed on one surface of the current collector becomes the outermost electrode. Were stacked alternately. Then, the current collecting tab portions of each positive electrode are collectively welded and integrated, and the current collecting tab portions of each negative electrode are collectively welded and integrated, and then the whole is stopped with a binding tape to obtain an electrode group. .

The electrode group was placed in the outer case so that the PET film side faced the inner surface of the outer case (positive electrode case), and the integrated current collecting tab portion of each 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 40 mg, cover the outer case containing the electrode group, caulk the periphery, the diameter is 8.5 mm, the thickness is 5.4 mm, and the number of positive and negative electrodes in the electrode group is different. 9 and a flat non-aqueous secondary battery having the same structure as that shown in FIG. 10 was obtained.

Comparative Example 1
The same positive electrode mixture layer forming paste as that used in Example 1 was intermittently applied to the surface of a long aluminum foil having a thickness of 15 μm, dried, roll-pressed, and then cut. A positive electrode having the same shape as that produced and having a positive electrode mixture layer having the same thickness on both sides of the current collector was produced. In the positive electrode obtained, the angles A and A ′ shown in FIG. 4 were 3 °, and the length a shown in FIG. 4 was 0.8 mm.

  Further, the same negative electrode mixture layer forming paste as that used in Example 1 was intermittently applied to the surface of a long copper foil having a thickness of 10 μm, dried, roll-pressed, and cut. A negative electrode having the same shape as that prepared in 1 and having a negative electrode mixture layer having the same thickness on one side or both sides of the current collector was produced. The obtained negative electrode had an angle of B and B ′ shown in FIG. 5 of 3 °, and the length of b shown in FIG. 5 was 0.8 mm.

  A flat nonaqueous secondary battery was produced in the same manner as in Example 1 except that the positive electrode and the negative electrode were used.

Comparative Example 2
A positive electrode and a negative electrode were produced in the same manner as in Example 1 except that the mold used for forming the positive electrode mixture layer related to the positive electrode and the negative electrode mixture layer related to the negative electrode was changed to one having a hole inclination angle of 90 °. As a result, when the mold was removed after the paste was filled in the mold holes and dried, cracks occurred at the ends of the mixture layer (positive electrode mixture layer and negative electrode mixture layer). . When a flat non-aqueous secondary battery is manufactured using such a positive electrode and a negative electrode, there is a high possibility that cracking will occur at the end of the mixture layer with reduced strength. If a crack occurs, it may cause a short circuit, resulting in a flat non-aqueous secondary battery that is determined to be defective. Therefore, in Comparative Example 2, the production of the flat non-aqueous secondary battery was stopped.

  For each of the 20 nonaqueous secondary batteries of Example 1 and Comparative Example 1, the discharge capacity at a current value of 3.6 mA was measured. These results are listed in Table 1. Also, Table 1 shows the inclination angle of the holes according to the mold used for the production of the positive electrode and the negative electrode, the angles A and A ′ shown in FIG. 4 of the positive electrode mixture layer (in Table 1, “end of the positive electrode mixture layer” 4) of the positive electrode mixture layer (described as “positional displacement of the positive electrode mixture layer” in Table 1) and B shown in FIG. 5 of the negative electrode mixture layer. And the angle of B ′ (described as “end slope of negative electrode mixture layer” in Table 1), and the length of b of the negative electrode mixture layer shown in FIG. 5 (in Table 1, “the negative electrode mixture layer Also described as “positional deviation”.

  As shown in Table 1, the flat nonaqueous secondary battery of Example 1 has a higher capacity than the battery of Comparative Example 1.

  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.

DESCRIPTION OF SYMBOLS 1 Flat type non-aqueous secondary battery 2 Positive electrode case 3 Negative electrode case 4 Insulation gasket 5 Positive electrode 5a Main body part of positive electrode 5b Positive electrode current collection tab part 6, 6A, 6B Negative electrode 6a Negative electrode body part 6b Negative electrode current collection tab part 7 Separator 7c Joint 8 Insulating material 100 Mold for electrode mixture layer formation

Claims (9)

An electrode used in a non-aqueous secondary battery having an electrode group in which a plurality of electrodes are stacked substantially in parallel via a separator, and a main body part, and a current collecting tab part protruding from the main body part in plan view An electrode mixture layer containing an electrode active material is formed on one side or both sides of the current collector, and the current collector tab portion has an electrode mixture layer on the current collector. Is not formed, the current collector is exposed, the side surface of the electrode mixture layer at the boundary portion with the exposed portion of the current collector, and the surface in contact with the current collector in the electrode mixture layer; A method for producing an electrode having an angle between 45 ° and less than 90 °,
An electrode mixture layer forming mold is disposed on the surface of the current collector, the electrode mixture layer forming composition containing the electrode active material and the solvent is filled in the holes of the mold and dried, and then the A step of removing the mold,
The hole of the mold is inclined such that the opening area on the current collector side is larger than the opening area on the opposite side of the current collector. Production method.   2. The non-electrode according to claim 1, wherein an angle between a side surface of the electrode mixture layer at a boundary portion with the exposed portion of the current collector and a surface in contact with the current collector in the electrode mixture layer is 86 ° or less. A method for producing an electrode for a water secondary battery.   An electrode mixture layer is formed on both sides of the current collector, and a side surface of the electrode mixture layer formed on both sides of the current collector at a boundary portion with an exposed portion of the current collector, and the electrode mixture The method for producing an electrode for a nonaqueous secondary battery according to claim 1, wherein the angle between the surface of the agent layer and the surface in contact with the current collector is 45 ° or more and less than 90 °.   The angle between the side surface of the electrode mixture layer formed on both surfaces of the current collector at the boundary portion with the exposed portion of the current collector and the surface in contact with the current collector in the electrode mixture layer, The method for producing an electrode for a non-aqueous secondary battery according to claim 3, wherein both are 86 ° or less.   A boundary portion between the exposed portion of the current collector in the electrode mixture layer formed on one side of the current collector and an exposed portion of the current collector in the electrode mixture layer formed on the other surface of the current collector The method for producing an electrode for a nonaqueous secondary battery according to claim 3 or 4, wherein the positional deviation from the boundary portion is 0.1 mm or less. A mold for forming an electrode mixture layer is disposed on one side of the current collector, and the composition for forming an electrode mixture layer containing an electrode active material and a solvent is placed in the hole of the mold disposed on one side of the current collector. Filling and drying (I),
While the mold used in the step (I) is arranged on one side of the current collector, an electrode mixture layer forming mold is arranged on the other side of the current collector to form an electrode mixture layer A step (II) of filling the composition with a hole in the mold placed on the other side of the current collector and drying, and after the completion of the step (II), placed on one side and the other side of the current collector Removing the mold (III)
The manufacturing method of the electrode for non-aqueous secondary batteries in any one of Claims 1-5 which manufactures the electrode for non-aqueous secondary batteries in which the electrode mixture layer is formed in both surfaces of an electrical power collector. A non-aqueous secondary battery comprising an electrode group in which positive electrodes and negative electrodes are alternately and substantially parallel laminated with separators, and the total number of positive and negative electrodes is three or more, and a non-aqueous electrolyte A method of manufacturing comprising:
A method for producing a non-aqueous secondary battery, comprising the step of producing the positive electrode and / or the negative electrode by the method for producing an electrode for non-aqueous secondary battery according to claim 1.   In the space formed by caulking and sealing the exterior case and the sealing case via an insulating gasket, the electrode group and the non-aqueous electrolyte are accommodated, and the laminated surface of the positive electrode, the negative electrode, and the separator in the electrode group is The method for manufacturing a non-aqueous secondary battery according to claim 7, wherein the outer case and the sealing case are substantially parallel to a flat surface. A separator made of a microporous film made of a thermoplastic resin is disposed on each side of the positive electrode at least on both sides facing the negative electrode,
The two separators disposed on both surfaces of the positive electrode include a main body part that covers the entire surface of the main body part of the positive electrode, and a boundary part that protrudes from the main body part and at least the main body part of the current collecting tab part of the positive electrode. 9. The non-aqueous two according to claim 7, further comprising an overhanging portion that covers the portion, and forming a welded portion that is welded to each other in at least a part of the peripheral edge portion of the main portion of the two separators. A method for manufacturing a secondary battery.

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