JP2012104274A - Electrode, battery, and manufacturing method of electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode capable of suppressing short circuit current in internal short circuit even in the event of dilation of the electrode.SOLUTION: An electrode (3) includes a plurality of divided active material layers (22, 23) formed on a collector (4). Between the adjacent two divided active material layers (22, 23), a high resistance member (27) which is higher than the active material layers (22, 23) in electric resistance and has ion permeability is included.

Description

  The present invention relates to an electrode, a battery, and an electrode manufacturing method, and more particularly to an electrode for a battery.

  A battery electrode that divides an active material layer formed on a current collector is disclosed (see Patent Document 1).

JP 2008-53088 A

  By the way, in the technique of the above-mentioned patent document 1, when an internal short circuit occurs inside the active material layer, the active material layer is divided into a plurality of parts, so that the current collection area of one divided active material layer becomes small, and the short circuit occurs. Current concentration on the part is suppressed.

  However, it is conceivable that two adjacent active material layers are brought into contact with each other due to the expansion of the electrode due to charge and discharge, and in this case, there is a possibility that current concentration at the short-circuited portion may occur again.

  Then, an object of this invention is to provide the manufacturing method of the electrode which can suppress the short circuit current at the time of an internal short circuit even if there exists expansion | swelling of an electrode.

  The electrode of the present invention is an electrode in which an active material layer divided into a plurality of current collectors is formed. Then, a high resistance member having higher ion resistance and ion permeability than the active material layer is included between two adjacent active material layers.

  According to the present invention, even when the electrodes expand, the electrical resistance between the electrodes divided by the high resistance member can be kept high, so that the short circuit current at the time of an internal short circuit can be suppressed.

1 is a schematic plan view of a stacked battery according to a first embodiment of the present invention. It is a schematic plan view of one bipolar electrode of the first embodiment. It is the sectional view on the AA line of FIG. It is a schematic plan view of one bipolar electrode of the second embodiment. It is the sectional view on the AA line of FIG. It is a schematic plan view of one bipolar electrode of the third embodiment. It is the sectional view on the AA line of FIG. It is a schematic sectional drawing of two bipolar electrodes of 3rd Embodiment. It is a schematic plan view of one bipolar electrode of the fourth embodiment. FIG. 10 is a sectional view taken along line AA in FIG. 9. It is a schematic sectional drawing of two bipolar electrodes of 4th Embodiment. It is a schematic plan view of one bipolar electrode of the fifth embodiment. It is AA sectional view taken on the line of FIG. It is a schematic plan view of one bipolar electrode of the sixth embodiment. It is AA sectional view taken on the line of FIG. It is a schematic plan view of one bipolar electrode of the seventh embodiment. It is the sectional view on the AA line of FIG. It is a schematic plan view of one bipolar electrode of the eighth embodiment. It is the sectional view on the AA line of FIG. It is a schematic plan view of one bipolar electrode of a comparative example. It is AA sectional view taken on the line of FIG. It is a schematic plan view of one bipolar electrode of the ninth embodiment. It is AA sectional view taken on the line of FIG. It is a schematic plan view of one bipolar electrode of the tenth embodiment. It is AA sectional view taken on the line of FIG. It is a schematic sectional drawing of the modification of 10th Embodiment. It is a schematic plan view of one bipolar electrode of the eleventh embodiment. It is the sectional view on the AA line of FIG. It is the BB sectional drawing of FIG. It is a schematic plan view of one bipolar electrode of the twelfth embodiment. It is AA sectional view taken on the line of FIG. It is a schematic plan view of one bipolar electrode of the thirteenth embodiment. It is AA sectional view taken on the line of FIG. It is a schematic plan view of one bipolar electrode of 14th Embodiment. It is the sectional view on the AA line of FIG. FIG. 35 is a sectional view taken along line BB in FIG. 34. It is a schematic block diagram of an electrode manufacturing apparatus. It is explanatory drawing which shows the process performed with the 2nd press apparatus and the 2nd coating device in the case of Examples 1-4. It is explanatory drawing which shows the process performed by the 2nd press apparatus and the 2nd coating device in the case of Example 5, 6. FIG. It is a model figure which shows the collection of porous particles. It is a model figure which shows the collection of particle | grains. It is a model figure which shows the gathering of a filler. It is a schematic longitudinal cross-sectional view of the stack of 8th Embodiment.

  Embodiments will be described below with reference to the drawings. In the following drawings, in order to facilitate understanding of the invention, the thickness and shape of each layer such as elements constituting the stacked battery are exaggerated.

(First embodiment)
FIG. 1 is a schematic longitudinal sectional view of a stack 1 according to a first embodiment of the present invention. Note that the negative electrode active material layer and the positive electrode active material layer are not divided.

  First, the stack 1 will be outlined. The stack 1 is a unit constituting a stacked secondary battery. In FIG. 1, it is assumed that the upper direction is the vertical upper direction, the lower direction is the vertical lower direction, and the direction orthogonal to the vertical direction is the horizontal direction.

  As will be described later, the stack 1 uses a resin-metal composite laminate film as an exterior material, and houses a power generation element 2 therein. The power generation element 2 includes a bipolar electrode in which a positive electrode active material layer is formed on one surface of a current collector and a negative electrode active material layer is formed on the other surface, and an electrolyte in which ions move inside. A plurality of unit cell layers are laminated by laminating a positive electrode active material layer and a negative electrode active material layer of an electrode so as to face each other with the electrolyte therebetween. Hereinafter, the power generation element 2 will be outlined.

  The flat rectangular current collector 4 having a short side and a long side is formed of a resin in which a conductive filler is added to a conductive polymer material or a non-conductive polymer material. According to the resin current collector 4, the in-plane internal resistance of the current collector 4 is relatively greater than that of the metal current collector.

  In the stack 1, the positive electrode active material layer 5 (positive electrode) is formed on the vertical lower surface of the current collector 4 placed in the horizontal direction in FIG. 1, and the negative electrode active material layer 6 (negative electrode) is formed on the vertical upper surface of the current collector 4. There are five (a plurality) of bipolar electrodes 3 formed. The negative electrode active material layer 6 has a larger surface area than the positive electrode active material layer 5. Each bipolar electrode 3 is laminated in the vertical direction via an electrolyte layer 7 (connected in series) to form one stack 1.

  Here, when two bipolar electrodes adjacent in the vertical direction are respectively an upper bipolar electrode and a lower bipolar electrode, the negative electrode active material layer 6 positioned on the upper surface of the lower bipolar electrode and the lower surface of the upper bipolar electrode The lower and upper bipolar electrodes are arranged so that the positive electrode active material layer 5 located at the position facing each other through the electrolyte layer 7.

  The outer periphery in the horizontal direction of the two electrode active material layers 5 and 6 of the positive electrode and the negative electrode is formed slightly narrower than the outer periphery in the horizontal direction of the current collector 4. The positive electrode active material layer 5 and the negative electrode are formed by sandwiching a sealing material 11 having a predetermined width around the peripheral portion (horizontal circumference) of the current collector 4 where the two electrode active material layers 5 and 6 are not provided. In addition to insulating the active material layer 6, a predetermined space 8 is formed between the two electrode active material layers 5, 6 facing in the vertical direction in FIG. 1. Further, the sealing material 11 is disposed outside the horizontal end portions of the two active material layers 5 and 6 with a margin.

  The space 8 is filled with a liquid, gel, or solid electrolyte 9 to form an electrolyte layer 7.

  The space 8 filled with the electrolyte 9 is provided with a separator 12 formed of a porous film, and the two electrode active material layers 5 and 6 that are opposed by the separator 12 are also prevented from being in electrical contact. Has been. Liquid or gel electrolyte 9 can pass through this separator 12. In the case of the solid electrolyte 9, the separator 12 is not provided.

  High current tabs 16 and 17 for charging and discharging the power generation element 2 are connected to current collectors positioned at both ends of the power generation element 2 in the stacking direction. That is, one high-power tab 16 is connected to the uppermost negative electrode active material layer 6, and the other high-power tab 17 is connected to the lowermost positive electrode active material layer 5. One high-power tab 17 functions as a positive terminal after charging of the bipolar secondary battery, and the other high-power tab 16 functions as a negative terminal after charging.

  A single cell layer 15 (single cell) is constituted by the positive electrode active material layer 5 and the negative electrode active material layer 6 sandwiching the electrolyte layer 7. Therefore, the stack 1 has a configuration in which the four cell layers 15 are connected in series.

  Although not shown, the entire power generation element 2 including the high voltage tabs 16 and 17 accommodates the power generation element 2 by using a resin-metal composite laminate film as an exterior material and bonding its peripheral part by heat fusion. Sealed in a vacuum. Out of the resin-metal composite laminate film, high voltage tabs 16 and 17 and five voltage detection terminals (not shown) are provided.

  Although the number of unit cell layers 15 connected in series is four in FIG. 1, the number of unit cell layers 15 connected in series and the number of stacks to be described later connected in series actually depend on the desired voltage. Adjust it. This completes the overview of stack 1.

  By using the current collector 4 made of resin, the current flow in the in-plane direction of the current collector 4 is suppressed, and long-term reliability due to local heat generation and a minute short circuit is improved. However, as the capacity of the battery is increased, the internal resistance in the in-plane direction of the current collector 4 is reduced by increasing the capacity and increasing the thickness of the active material layer. The problem of lowering occurred. This is because the negative electrode active material layer 6 and the positive electrode active material layer 5 are collectively formed on each surface of the current collector 4. If a micro short circuit occurs in a part of the active material layers 6 and 5, current concentrates from the entire active material layers 6 and 5 to the micro short circuit part, which may promote self-discharge and shorten the battery life. is there.

  In order to solve this problem, there is one in which current concentration generated in the electrode active material layer is suppressed by dividing the electrode active material layer into a plurality of parts.

  However, even in such a bipolar electrode, stress acting on the bipolar electrode, for example, expansion / contraction due to stress generated by charging / discharging, temperature change, external vibration, etc. occurs. Due to this expansion / contraction, two adjacent electrode active material layers may be brought into contact with each other. In this case, current concentration may occur in the short-circuited portion.

  Therefore, in the present embodiment, a high resistance member having higher electric resistance and ion permeability than the electrode active material layer is provided between two adjacent electrode active material layers. This will be described in detail below.

  FIG. 2 is a schematic plan view of one bipolar electrode 3 of the first embodiment, and FIG. 3 is a cross-sectional view taken along line AA of FIG. However, in FIG. 3, only the electrode active material layer 21 formed on one surface (upper surface) of the current collector 4 is shown, and the electrode active material layer 21 formed on the other surface (lower surface) of the current collector 4 is Not abbreviated. Here, the “electrode active material layer” refers to either the positive electrode active material layer or the negative electrode active material layer. More specifically, when the electrode active material layer 21 formed on one surface of the current collector 4, for example, the upper surface is a negative electrode active material layer, the electrode active formed on the other surface (lower surface) of the current collector 4. The material layer (not shown) becomes a positive electrode active material layer. On the other hand, when the electrode active material layer 21 formed on one surface, for example, the upper surface, of the current collector 4 is a positive electrode active material layer, the electrode active material layer formed on the other surface (lower surface) of the current collector 4 (Not shown) is a negative electrode active material layer.

  In the first embodiment, a case where the electrode active material layer 21 as a group is divided into two (equal parts) is shown. For this reason, the two divided electrode active material layers (the divided electrode active material layers are hereinafter referred to as “divided electrode active material layers”) 22 and 23 are arranged with a predetermined gap 25 therebetween. The gap 25 generated by the division is hereinafter referred to as “divided portion”. The divided electrode active material layers 22 and 23 include long side surfaces 22a and 23a that face each other, long side surfaces 22b and 23b that do not face each other, and a flat surface (lower surface in FIG. 3) 22c that contacts the current collector 4. 23c, planes 22d and 23d on the side not in contact with the current collector 4 (upper surface in FIG. 3). The cross sections of the divided electrode active material layers 22 and 23 are substantially rectangular as shown in FIG.

  The reason for dividing the number into the minimum two is for simplification. Therefore, it may be divided into three (the case of dividing into three will be described in the eighth embodiment). The number of divisions is not limited to two or three, and may be any number. The division method is not limited. It may be divided in one direction or may be divided in a lattice shape. When divided in one direction, as shown in FIG. 2 and FIG. 18 described later, the divided electrode active material layers are aligned in a line and divided into a lattice shape, the divided electrode active material layers are in a matrix shape. To align.

  Then, a high resistance member 27 having an electric resistance higher than that of the electrode active material layer 21 and having ion permeability is provided only in a part of the divided portion 25, here in the center of the divided portion 25. Here, the high resistance member having an electric resistance higher than that of the electrode active material layer and having ion permeability may be hereinafter referred to as “high resistance member having ion permeability” or simply “high resistance member”. As shown in FIG. 3, the cross section of the high resistance member 27 is also rectangular.

  The reason why the high resistance member having higher electric resistance than the electrode active material layer also has ion permeability is that if the high resistance member having no ion permeability is provided in the divided portion 25, the high resistance member is interposed. This is because the electrolytic solution does not permeate into the portion to be subjected to and the electrode characteristics are considered to deteriorate. Here, ion permeability is also referred to as ion conductivity. Moreover, having ion permeability is almost synonymous with being porous.

  The position where the high resistance member having ion permeability is provided is not limited to the center position of the divided portion 25. What is necessary is just to provide in any position of the division | segmentation site | part 25. FIG.

  Examples of the material of the high resistance member 27 having ion permeability include an insulating ceramic such as alumina and a high resistance organic material such as polyethylene oxide (PEO). Since these particles become porous particles 71 as shown in FIG. 40, they have ion permeability.

  Note that the material of the high resistance member having ion permeability is not limited to the porous material from the beginning. The material itself may not be porous. For example, as shown in FIG. 41, by forming particles 72 that are high-resistance particles but do not have holes, gaps (holes) 73 are created between the particles 72 and the particles 72. If it does, it will perform the same function as a collection of porous particles as a whole. Similarly, as shown in FIG. 42, a void 74 is formed between the filler 74 and the filler 74 by forming a shape in which fillers 74 having high resistance but not having holes are gathered. If it does, it will work the same as a collection of porous particles as a whole.

  Thus, according to the first embodiment, the bipolar electrode 3 (electrode) in which the electrode active material layer 21 divided into two parts is formed on each surface of the current collector 4, and two adjacent divided electrodes are provided. Since the high resistance member 27 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is provided in the divided portion 25 between the active material layers 22 and 23, the bipolar electrode 3 caused by vibration or heat is provided. Even if the divided electrode active material layers 22, 23 formed on the same surface of the current collector 4 due to expansion or contraction of the material are approaching each other, the high resistance member 27 prevents the divided electrode active material layers 22, 23 from approaching each other. It is possible to suppress conduction between the formed divided electrode active material layers 22 and 23.

  As a result, even if a minute internal short circuit occurs in one divided electrode active material layer 22, current concentration from the other divided electrode active material layer 23 can be avoided. That is, even when there is a minute internal short circuit in any one of the divided electrode active material layers 22 and 23, a decrease in battery capacity due to self-discharge can be minimized.

  The divided electrode active material layers 22 and 23 originally have ion permeability. Having the ion permeability in the divided electrode active material layers 22 and 23 and the high resistance member 27 is equivalent to having a large number of holes in the divided electrode active material layers 22 and 23 and the high resistance member 27. In this case, in the first embodiment, the average hole diameter of the high resistance member 27 is made substantially equal to the average hole diameter of the divided electrode active material layers 22 and 23. For this reason, the high resistance member 27 permeate | transmits the ion (for example, Li ion) which contributes to a battery reaction. As a result, Li ions are easily supplied to the divided electrode active material layers 22 and 23 close to the current collector 4.

(Second Embodiment)
FIG. 4 is a schematic plan view of one bipolar electrode 3 of the second embodiment, which replaces FIG. 2 of the first embodiment. 5 is a cross-sectional view taken along line AA in FIG. 4 and 5, the same parts as those in FIGS. 2 and 3 are denoted by the same reference numerals.

  The outer dimensions of the divided electrode active material layers 22 and 23 and the ion-permeable high resistance member 27 ′ of the second embodiment are the same as the divided electrode active material layers 22 and 23 and the ion-permeable high resistance member of the first embodiment. It is the same as the external dimensions of 27. In the second embodiment, the average hole diameter of the high resistance member 27 ′ having ion permeability is made larger than the average hole diameter of the divided electrode active material layers 22 and 23.

  Here, as a material of the high resistance member 27 ′ having ion permeability, the average pore diameter of the divided electrode active material layers 22 and 23 from the high resistance member 27 having ion permeability described in the first embodiment is used. What is necessary is just to select what becomes larger than an average hole diameter. Alternatively, the particle shape and filler shape shown in FIGS. 41 and 42 may be created so that the average pore diameter is larger than the average pore diameter of the divided electrode active material layers 22 and 23.

  The average particle size of the material of the high resistance member 27 ′ having ion permeability is desirably larger than the average particle size of the active material particles constituting the divided electrode active material layers 22 and 23.

  According to the second embodiment, the average hole diameter of the high resistance member 27 ′ having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is larger than the average hole diameter of the divided electrode active material layers 22 and 23. Since it is large, the electrolytic solution is more easily penetrated than the high resistance member 27 having ion permeability of the first embodiment, and the electrode characteristics can be improved as compared with the case of the first embodiment.

  6, 9, 12, 14, and 16 are schematic plan views of one bipolar electrode 3 of the third, fourth, fifth, sixth, and seventh embodiments. FIG. 2 replaces FIG. 7, FIG. 10, FIG. 13, FIG. 15 and FIG. 17 are sectional views taken along line AA of FIG. 6, FIG. 9, FIG. 6 to 17, the same parts as those in FIGS. 2 and 3 are denoted by the same reference numerals. However, as in the first embodiment, FIGS. 7, 10, 13, 15, and 17 show only the electrode active material layer 21 formed on one surface (upper surface) of the current collector 4, The electrode active material layer 21 formed on the other surface (lower surface) of the electric body 4 is not shown.

(Third embodiment)
First, in the third embodiment shown in FIGS. 6 and 7, all of the two divided electrode active material layers 22 and 23 and all of the divided portions 25 are high resistance members having higher electric resistance and ion permeability than the active material layer. 28. For this reason, the cross section of the high resistance member 28 having ion permeability has a shape in which the shape of the letter “E” is depressed as shown in FIG.

  In the third embodiment, when the two bipolar electrodes 3 are stacked in the vertical direction, the high resistance members 28 face each other as shown in FIG. In this case, if the divided electrode active material layers 22 and 23 of one bipolar electrode 3 positioned vertically upward are positive electrode active material layers, the divided electrode active material layer 22 of the other bipolar electrode 3 positioned vertically downward is the same. , 23 are negative electrode active material layers.

  According to the third embodiment, all of the divided portions 25 between the two adjacent divided electrode active material layers 22 and 23 have a higher resistance and higher ion resistance than the divided electrode active material layers 22 and 23. Since the member 28 is provided, even if the divided electrode active material layers 22 and 23 formed on the same surface of the current collector 4 try to approach each other, the high resistance member 28 prevents the divided electrode active material layers 22 and 23 from approaching each other. It is possible to further suppress the conduction between the divided electrode active material layers 22 and 23 formed in the first embodiment as compared with the first embodiment.

  In addition, according to the third embodiment, since the high resistance member 28 is disposed on the entire opposing surface of the two bipolar electrodes 3 adjacent in the stacking direction, the division of one bipolar electrode 3 adjacent in the stacking direction is performed. The probability of occurrence of an internal short circuit between the electrode active material layers 22 and 23 and the divided electrode active material layers 22 and 23 of the other bipolar electrode 3 adjacent in the stacking direction can be reduced.

  In addition, according to the third embodiment, the divided electrode active material layers 22 and 23 of one bipolar electrode 3 adjacent in the stacking direction and the divided electrode active material layer 22 of the other bipolar electrode 3 adjacent in the stacking direction. , 23 can be made constant in the stacking direction distance, so that the battery reaction easily proceeds uniformly. On the other hand, the difference in the distance between two divided electrode active material layers facing in the stacking direction between two bipolar electrodes 3 adjacent in the stacking direction means that the resistance in the divided electrode active material layer is different (ion of ions). This means that the resistance changes because the moving distance changes). Then, the susceptibility of the reaction changes in the divided electrode active material layer, and the reaction becomes nonuniform in the divided electrode active material layer.

  Now, as shown in FIG. 8, the high resistance member 28 having ion permeability is connected to the first portion 28a parallel to the current collector 4 covering the flat surfaces 22d and 23d on the side not in contact with the current collector 4. The second portion 28b provided in the divided portion 25 and the third portions 28c and 28d provided along the long side surfaces 22b and 23b opposite to the long side surfaces 22a and 23a are divided. At this time, it is desirable that the first portion 28a is thinner than the second portion. This is because the capacity density of the battery can be reduced not much by making the first part 28a thinner than the second part.

(Fourth embodiment)
In the fourth embodiment shown in FIG. 9 and FIG. 10, a high resistance member 29 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is provided in all of the divided portions 25, and the divided electrode active material layers are provided. High resistance members 30 and 31 having higher ion resistance and higher ion resistance than the divided electrode active material layers 22 and 23 are also provided on the long side surfaces 22b and 23b opposite to the side where the divided portion 25 is present. It is provided.

  In the fourth embodiment, when the two bipolar electrodes 3 are stacked in the vertical direction, the result is as shown in FIG. In this case, if the divided electrode active material layers 22 and 23 of one bipolar electrode 3 positioned vertically upward are positive electrode active material layers, the divided electrode active material of the other bipolar electrode 3 positioned vertically downward is provided. The layers 22 and 23 become negative electrode active material layers.

  As can be seen from a comparison of FIG. 11 with FIG. 8 of the third embodiment, the fourth embodiment corresponds to a structure in which the first portion 28a is removed from the ion-permeable high resistance member 28 of the third embodiment. To do. That is, the high resistance member 29 having ion permeability according to the fourth embodiment corresponds to a second part provided in the divided part 25 in the third embodiment. The high resistance members 30 and 31 having ion permeability according to the fourth embodiment are provided at third portions provided along the long side surfaces 22b and 23b opposite to the side where the divided portion 25 is referred to in the third embodiment. Equivalent to.

  According to the fourth embodiment, all of the divided portions 25 between the two adjacent divided electrode active material layers 22 and 23 have a higher resistance than the divided electrode active material layers 22 and 23 and higher ion resistance. Since the member 29 is provided in the same manner as in the third embodiment, even if the divided electrode active material layers 22 and 23 formed on the same surface of the current collector 4 try to approach each other, the high resistance member 29 prevents the current from collecting. It is possible to further prevent electrical conduction between the divided electrode active material layers 22 and 23 formed on the same surface of the electric body 4 as compared with the first embodiment.

  Further, according to the fourth embodiment, the high resistance members 29, 30, and 31 are provided on all of the long side surfaces 22 a, 22 b, 23 a, and 23 b of the divided electrode active material layers 22 and 23. In other words, since the high resistance member is not provided on the flat surfaces 22d and 23d on the side where the divided electrode active material layers 22 and 23 do not contact the current collector 4, the capacity density of the battery can be increased accordingly.

(Fifth embodiment)
In the fifth embodiment shown in FIGS. 12 and 13, electric power is supplied from the divided electrode active material layers 22 and 23 to all of the long side surfaces 22 a and 23 a (end surfaces) of the two adjacent divided electrode active material layers 22 and 23. High resistance members 32 and 33 having high resistance and ion permeability are provided, and a gap portion 34 is provided between the high resistance members 32 and 33 (that is, the central position of the divided portion 25).

  Here, the horizontal width W <b> 1 (the distance between the gaps) of the gap 34 is set to be approximately the same as the average pore diameter of the divided electrode active material layers 22 and 23.

  As a material of the high resistance members 32 and 33 here, a thermoplastic resin, a thermosetting resin, and a binder for battery electrodes can be used. If a porous structure is formed using a thermoplastic resin, a thermosetting resin, a battery electrode binder, etc. (see FIGS. 41 and 42), ions permeate into the material itself like a thermoplastic resin and a thermosetting resin. Even if there is no property, it has ion permeability.

  According to the fifth embodiment, all of the long-side side surfaces 22a and 23a (end surfaces) of two adjacent divided electrode active material layers 22 and 23 have higher electric resistance than the divided electrode active material layers 22 and 23, and ion permeation. The high resistance members 32 and 33 having the properties are provided, and the gap portion 34 is provided between the high resistance members 32 and 33 (the center position of the divided portion 25). The electrolyte can be diffused more than in the case of the form. As a result, the electrolytic solution is easily permeable to the divided electrode active material layers 22 and 23 near the current collector 4 adjacent to the divided portion 25, so that the electrode characteristics can be improved.

  Further, according to the fifth embodiment, due to the presence of the gap 34, the stress acting between the two divided electrode active material layers 22 and 23 adjacent to each other when the divided electrode active material layers 22 and 23 are thermally expanded or contracted is exerted. It becomes easy to relax.

(Sixth embodiment)
In the sixth embodiment shown in FIGS. 14 and 15, electric power is supplied from the divided electrode active material layers 22 and 23 to all of the long side surfaces 22 a and 23 a (end surfaces) of the two adjacent divided electrode active material layers 22 and 23. The fifth is that high resistance members 32 and 33 having high resistance and ion permeability are provided, and a gap 34 ′ is provided between the high resistance members 32 and 33 (the center position of the divided portion 25). This is the same as the embodiment.

  The sixth embodiment is different from the fifth embodiment in that the horizontal width W2 (the distance between the gaps) of the gap 34 ′ is larger than the average pore diameter of the divided electrode active material layers 22 and 23. Is a point.

  According to the sixth embodiment, the horizontal width W2 (the distance between the gaps) of the gap 34 ′ is made larger than the average pore diameter of the divided electrode active material layers 22 and 23. Since it becomes easy to permeate also to the adjacent collector 4 side, an electrode characteristic can be improved.

(Seventh embodiment)
In the seventh embodiment shown in FIGS. 16 and 17, the areas of the planes (lower surfaces in FIG. 17) 22 c and 23 c of the divided electrode active material layers 22 and 23 in contact with the current collector 4 are the same as those in the first embodiment. The area of the divided electrode active material layers 22 and 23 on the side in contact with the current collector 4 (lower surface in FIG. 3) 22c and 23c is larger than the area, and the divided electrode active material layers 22 and 23 are in contact with the current collector 4 The areas of the non-contact planes (upper surface in FIG. 17) 22d and 23d are the same as the planes (upper surfaces in FIG. 3) 22c and 23c of the divided electrode active material layers 22 and 23 of the first embodiment that do not contact the current collector 4 And a high resistance member 35 having a higher electric resistance than that of the divided electrode active material layers 22 and 23 and having ion permeability. For this reason, as shown in FIG. 17, the cross section of the divided electrode active material layers 22 and 23 is an isosceles trapezoid, and the cross section of the high resistance member 35 having ion permeability is an inverted trapezoid.

  According to the seventh embodiment, the contact area between the divided electrode active material layers 22 and 23 and the current collector 4 is larger than that of the first embodiment, so that the current collector 4 and the divided electrode active material layers 22 and 23 are in close contact with each other. Strength can be strengthened.

  In addition, according to the seventh embodiment, the horizontal width of the divided portion 25 increases as it moves vertically upward from the current collector 4, so that the divided electrode active material is separated at the portion of the divided portion 25 away from the current collector 4. The stress acting between the two divided electrode active material layers 22 and 23 adjacent to each other at the time of thermal expansion or contraction of the layers 22 and 23 can be relaxed. More specifically, when the divided electrode active material layers 22 and 23 are in contact with each other when they are expanded, they are pressed against each other, so that stress is generated. Considering simply, the stress generated when the contact is made from the beginning is determined by the amount of expansion from the state where the contact is not made x the elastic modulus. The stress generated between the adjacent two divided electrode active material layers 22 and 23 is reduced when there is a gap that can expand freely until the two adjacent divided electrode active material layers 22 and 23 come into contact with each other. be able to. In other words, as the distance from the current collector 4 increases vertically, the horizontal width of the divided portion 25 increases, and the stress acting between the two adjacent divided electrode active material layers 22 and 23 can be relaxed.

(Eighth embodiment)
18 is a schematic plan view of one bipolar electrode 3 according to the eighth embodiment, and FIG. 19 is a cross-sectional view taken along line AA of FIG.

  In the eighth embodiment, the negative electrode active material layer 41 and the positive electrode active material layer 45 formed on each surface of the current collector 4 are divided (equally divided) into the same number (here, three), and the divided negative electrode active materials are divided. The material layer (this divided negative electrode active material layer is hereinafter referred to as “divided negative electrode active material layer”) 42, 43, 44 and the divided positive electrode active material layer (this divided positive electrode active material layer is hereinafter referred to as “divided negative electrode active material layer”). The positive electrode active material layer is referred to as the positive electrode active material layer.) 46, 47 and 48 are opposed to each other with the current collector 4 interposed therebetween, and the horizontal widths of the divided portions 49 and 50 on the divided negative electrode active material layers 42, 43 and 44 side are The divided negative electrode active material layer is made smaller than the horizontal width of the divided portions 51, 52 on the divided positive electrode active material layers 46, 47, 48 side, and is divided on the divided portions 49, 50 on the divided negative electrode active material layers 42, 43, 44 side. High resistance member 53 having higher electrical resistance than 42, 43 and 44 and having ion permeability 54, high resistance members 55 and 56 having higher electric resistance and ion permeability than the divided positive electrode active material layers 46, 47, 48 are provided at the divided portions 51, 52 on the divided positive electrode active material layers 46, 47, 48 side. It is a thing. Here, the horizontal width W3 of the three divided negative electrode active material layers 42, 43, 44 is larger than the horizontal width W4 of the three divided positive electrode active material layers 46, 47, 48.

  Further explanation will be given. Now, three divided negative electrode active material layers 42, 43, and 44 having the same outer dimensions are distinguished by a first divided negative electrode active material layer 42, a second divided negative electrode active material layer 43, and a third divided negative electrode active material layer 44. . Further, the three divided positive electrode active material layers 46, 47, and 48 having the same outer dimensions are distinguished by the first divided positive electrode active material layer 46, the second divided positive electrode active material layer 47, and the third divided positive electrode active material layer 48. . At this time, the longitudinal center line C1 of the first divided negative electrode active material layer 42 and the longitudinal center line (not shown) of the first divided positive electrode active material layer 46 are aligned in the left-right direction in FIGS. Similarly, the longitudinal center line C2 of the second divided negative electrode active material layer 43 and the longitudinal center line (not shown) of the second divided positive electrode active material layer 47 are aligned in the left-right direction in FIGS. Similarly, the longitudinal center line C3 of the third divided negative electrode active material layer 44 and the longitudinal center line (not shown) of the third divided positive electrode active material layer 48 are aligned in the left-right direction in FIGS.

  Accordingly, as shown in FIG. 19, the divided negative electrode active material layers 42, 43, and 44 include the divided positive electrode active material layers 46, 47, and 48 with the current collector 4 interposed therebetween.

  The divided negative electrode active material layers 42, 43, 44 have long side surfaces 42 a, 43 a, 43 b, 44 b that face each other, long side surfaces 42 b, 44 a that do not face each other, and planes that come into contact with the current collector 4. (Lower surface in FIG. 19) 42c, 43c, 44c and flat surfaces (upper surface in FIG. 19) 42d, 43d, 44d on the side not in contact with the current collector 4. Similarly, the divided positive electrode active material layers 46, 47, 48 are arranged on the long side surfaces 46 a, 47 a, 47 b, 48 b facing each other, the long side surfaces 46 b, 48 a not facing each other, and the side in contact with the current collector 4. Planes (upper surface in FIG. 19) 46c, 47c, 48c, and flat surfaces (lower surface in FIG. 19) 46d, 47d, 48d on the side not in contact with the current collector 4 are provided. As shown in FIG. 19, the cross sections of the divided negative electrode active material layers 42, 43, 44 and the divided positive electrode active material layers 46, 47, 48 are substantially rectangular.

  In addition, a part of the divided portions 49 and 50 on the divided negative electrode active material layers 42 to 44 side, here also in the center of the divided portions 49 and 50, has higher electrical resistance than the divided negative electrode active material layers 42 to 44 and has ion permeability. High resistance members 53 and 54 are provided. In addition, a part of the divided parts 51 and 52 on the divided positive electrode active material layers 46 to 48 side, here also has a higher electric resistance and ion permeability than the divided positive electrode active material layers 46 to 48 only at the center of the divided parts 51 and 52. High resistance members 55 and 56 are provided. The cross sections of the high resistance members 53, 54, 55, and 56 are also rectangular.

  According to the eighth embodiment, the negative electrode active material layer 41 and the positive electrode active material layer 45 formed on each surface of the current collector are divided into the same number, and divided negative electrode active material layers 42 to 44 and divided positive electrode active material layers. 46 to 48 are opposed to each other with the current collector 4 interposed therebetween, and the horizontal widths of the divided portions 49 and 50 on the divided negative electrode active material layers 42 to 44 side are divided into divided portions on the divided positive electrode active material layers 46 to 48 side. The high resistance member which is smaller than the horizontal width of 51 and 52 and has higher electric resistance and ion permeability than the divided negative electrode active material layers 42 to 44 at the divided portions 49 and 50 on the divided negative electrode active material layers 42 to 44 side. 53, 54, 55, and 56 are divided into portions 51 and 52 on the side of the divided positive electrode active material layers 46 to 48, and have high resistance members 55 and 56 having higher electric resistance and ion permeability than the divided positive electrode active material layers 46 to 48. As shown in FIG. When two bipolar electrodes 3 adjacent to each other are considered, the divided positive electrode active material layers 46, 47, 48 of one bipolar electrode 3 adjacent to the stacking direction of the other bipolar electrode 3 adjacent to each other in the stacking direction It is included in the divided negative electrode active material layers 42, 43 and 44. As a result, when the stacked secondary battery is charged, the Li ion of the split positive electrode active material layer 46 of one bipolar electrode 3 adjacent in the stacking direction is exchanged with the other adjacent in the stacking direction via the electrolyte (electrolytic solution). Since it can be received by the divided negative electrode active material layer 42 of the bipolar electrode 3, the charge / discharge efficiency can be improved. Compared with the first to seventh embodiments, it is possible to suppress capacity deterioration during durability. Here, FIG. 43 is a schematic longitudinal sectional view of a stack 1 in which three bipolar electrodes 3 of the eighth embodiment are stacked in the vertical direction. Note that the present invention is not limited to the case where three bipolar electrodes 3 are stacked.

  Further explanation will be given. A portion of the other bipolar electrode 3 adjacent in the stacking direction that is not opposed to the divided positive electrode active material layer of the other bipolar electrode 3 and that is adjacent in the stacking direction is adjacent to the stacked negative electrode active material layer in the stacking direction. Almost no Li ions in the split positive electrode active material layer of the matching bipolar electrode 3 can be accepted. If there is no divided negative electrode active material layer of the other bipolar electrode 3 adjacent in the stacking direction at the facing portion of the divided positive electrode active material layer of one bipolar electrode 3 adjacent in the stacking direction, There is a possibility that Li ions coming out from the divided positive electrode active material layer of the bipolar electrode 3 may be deposited as lithium (Li) in different places. Therefore, in the eighth embodiment, the horizontal width W3 of the divided negative electrode active material layer of the other bipolar electrode 3 adjacent in the stacking direction is set to the horizontal width W3 of the one divided bipolar electrode 3 adjacent in the stack direction. It is made larger than the horizontal width W4, and Li ions emitted from the divided positive electrode active material layer of one bipolar electrode 3 adjacent in the stacking direction are surely divided into the negative electrode active of the other bipolar electrode 3 adjacent in the stacking direction. Incorporated into the material layer.

  In this sense, also in the first to seventh embodiments, when considering two bipolar electrodes 3 adjacent in the stacking direction, the high resistance member provided on one adjacent bipolar electrode 3 and the other adjacent It is preferable that the high resistance member provided on the bipolar electrode 3 is opposed to the current collector (or separator).

(Comparative example)
20 is a schematic plan view of one bipolar electrode 3 of the comparative example, and FIG. 21 is a cross-sectional view taken along line AA of FIG. 20 and 21, the same reference numerals are given to the same portions as those in FIGS. 18 and 19 of the eighth embodiment. The comparative example is obtained by removing the high resistance member from the bipolar electrode 3 of the eighth embodiment shown in FIGS. That is, the high resistance member is not provided in the comparative example.

  22, 24, 27, 30, 32, and 34 are schematic plan views of one bipolar electrode 3 of the ninth, tenth, eleventh, twelfth, thirteenth, and fourteenth embodiments. is there. 23 is a cross-sectional view taken along line AA in FIG. 22, FIG. 25 is a cross-sectional view taken along line AA in FIG. 24, and FIGS. 28 and 29 are cross-sectional views taken along line AA in FIG. . 31 is a cross-sectional view taken along line AA in FIG. 30, FIG. 33 is a cross-sectional view taken along line AA in FIG. 32, and FIGS. 35 and 36 are cross-sectional views taken along line AA in FIG. . The same parts as those in FIGS. 2 and 3 of the first embodiment are denoted by the same reference numerals. However, as in FIG. 3 of the first embodiment, in FIG. 23, FIG. 25, FIG. 26, FIG. 28, FIG. 29, FIG. The electrode active material layer 21 formed on the other surface (lower surface) of the current collector 4 is not shown. The ninth to fourteenth embodiments are different from the first to eighth embodiments in the shape and arrangement of a high resistance member having ion permeability.

(Ninth embodiment)
First, in the ninth embodiment shown in FIGS. 22 and 23, the lower surface 61 a of the high resistance member 61 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is fixed on the current collector 4. Is. In this case, both side surfaces 61b and 61c of the high-resistance member 61 facing the long side surfaces 22a and 23a of the divided electrode active material layers 22 and 23 are the long side surfaces 22a and 23a of the divided electrode active material layers 22 and 23. It is not in contact with.

(10th Embodiment)
In the tenth embodiment shown in FIGS. 24 and 25, both side surfaces 62b and 62c of the high resistance member 62 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 are provided on the divided electrode active material layers 22 and 23. It fixes to the long side surface 22a, 23a which mutually opposes.

  FIG. 26 shows a modification of the tenth embodiment, which replaces FIG. In this modification, one of the side surfaces 62b and 62c (the side surface 62b in this case) of the high resistance member 62 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is used as the divided electrode active material layers 22 and 23. Are fixed to one of the long side surfaces 22a and 23a facing each other (here, the long side surface 22a).

(Eleventh embodiment)
As described above with reference to FIGS. 22 and 23, in the ninth embodiment, the lower surface 61 a of the high resistance member 61 having higher electric resistance and ion permeability than the divided electrode active material layers 22, 23 is provided at the center of the divided portion 25. It fixed on the collector 4 at the location. On the other hand, in the eleventh embodiment shown in FIGS. 27 to 29, the lower surfaces 63 a and 64 a of the high resistance members 63 and 64 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 are formed on the divided portions 25. It fixes on the electrical power collector 4 at two places of an edge part. That is, in the eleventh embodiment, the two high resistance members 63 and 64 having ion permeability are formed. One high resistance member 63 is fixed to one end of the divided portion 25 and the other high resistance member 64 is divided. It is fixed to the other end of the region 25. Also in the eleventh embodiment, the side surfaces 63b, 63c, 64b, 64c of the high resistance members 63, 64 facing the long side surfaces 22a, 23a of the divided electrode active material layers 22, 23 are the divided electrode active material layers 22, 23. The long side surfaces 22a and 23a are not brought into contact with each other.

(Twelfth embodiment)
In the twelfth embodiment shown in FIGS. 30 and 31, the electrode active material layer 21 is divided into three (equal parts). For this reason, these three divided electrode active material layers (this divided electrode active material layer is hereinafter referred to as “divided electrode active material layer”) 22, 23, 24 are arranged with a predetermined gap 25 therebetween. . The gaps 25 and 26 generated by this division are also referred to as “divided parts” hereinafter.

  In the ninth embodiment shown in FIGS. 22 and 23 and the eleventh embodiment shown in FIGS. 27 to 29, the side surfaces 61b, 61c, 63b, 63c of the high resistance members 61, 63, 64 having ion permeability are provided. 64b and 64c are not brought into contact with the long side surfaces 22a and 23a of the divided electrode active material layers 22 and 23, respectively. On the other hand, in the twelfth embodiment shown in FIGS. 30 and 31, the lower surfaces 65a and 66a of the high resistance members 65 and 66 having higher electric resistance and ion permeability than the divided electrode active material layers 22, 23 and 24 are provided on the current collector. 4, and one side surfaces 65 c and 66 c of the high resistance members 65 and 66 are brought into contact with one of the long side surfaces 23 a and 24 a of the divided electrode active materials 23 and 24.

(13th Embodiment)
In the thirteenth embodiment shown in FIG. 32 and FIG. 33, the cross section of the high resistance member 67 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is fixed on the current collector 4 in a triangular shape. It is provided.

(14th Embodiment)
In the fourteenth embodiment shown in FIGS. 34 to 36, the lower surfaces 68 a and 69 a of the high resistance members 68 and 69 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 are provided at two locations of the divided portion 25. The one side surface 68c of one high resistance member 68 is fixed to only one long side surface 23a of the divided electrode active material layer 23 and one side surface of the other high resistance member 69. 69b is brought into contact with only one long side surface 22a of the divided electrode active material layer 22.

  Examples 1-7 and a comparative example were produced with respect to the said 1st-7th embodiment and a comparative example, respectively. Examples 1 to 7 and a comparative example will be described next. Here, the matters common to the seven examples and the comparative example are described first, and thereafter, the points different from the common matters are individually described for the seven examples and the comparative example.

<Preparation of positive electrode slurry>
A positive electrode slurry was prepared by mixing 85 wt% of lithium manganese oxide (LiMn ₂ O ₄ ) as a positive electrode active material, 5 wt% of acetylene black as a conductive additive, and 10 wt% of polyvinylidene fluoride (PVDF) as a binder. . N-methyl-pyrrolidone (NMP) was used as the slurry viscosity adjusting solvent.

<Adjustment of negative electrode slurry>
A negative electrode slurry was prepared by mixing 90 wt% of hard carbon as a negative electrode active material and 10 wt% of polyvinylidene fluoride (PVDF) as a binder. N-methyl-pyrrolidone (NMP) was used as the slurry viscosity adjusting solvent.

<Preparation of current collector>
As a conductive layer, a conductive polymer material in which a carbon material is dispersed in polyethylene (PE) resin is stretched to form a film having a thickness of 100 μm, and a current collector including a conductive resin layer is obtained. Produced.

<Production of bipolar electrode>
The negative electrode slurry was applied to one surface of the current collector and dried to form a negative electrode active material layer. The negative electrode active material layer was pressed to a thickness of 50 μm.

  Subsequently, the positive electrode slurry was applied to the other surface of the current collector and dried to form a positive electrode active material layer. Pressing was performed so that the thickness of the positive electrode active material layer was 60 μm.

  Thus, a bipolar electrode was completed in which the negative electrode active material layer was formed on one surface of the current collector and the positive electrode active material layer was formed on the other surface.

  The bipolar electrode is cut into 140 mm × 90 mm, and the peripheral portion of the electrode 10 mm is prepared with a portion to which the electrode (both positive and negative) is not applied in advance, so that the electrode portion of 120 mm × 70 mm and the peripheral portion of 10 mm A bipolar electrode with a seal allowance was fabricated.

<Production of high resistance member>
An insulator material and a binder material were mixed to prepare a slurry. Alumina was used as the insulator material. As a binder, carboxymethyl cellulose (CMC) was used at a ratio of 2 wt%. N-methyl-pyrrolidone (NMP) was used as a solvent.

<Preparation of electrolyte>
Concentration of lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte salt in a non-aqueous solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a ratio of EC: DEC = 1: 1 (volume ratio) Was dissolved to 1 mol / l to prepare a non-aqueous electrolyte.

<Preparation of laminated secondary battery>
Six bipolar electrodes obtained as described above were prepared, and a sealing member made of a polyethylene (PE) film was disposed around the positive electrode active material layer and the negative electrode active material layer. Furthermore, the positive electrode active material layer of one adjacent bipolar electrode and the negative electrode active material layer of the other adjacent bipolar electrode are opposed to each other, and a thickness of 35 μm is provided between these two adjacent bipolar electrodes. A separator made of polyethylene (PE) was placed and laminated. Next, the three sides of the seal part other than the liquid injection part of each layer are pressed from above and below (press pressure: 0.2 MPa, press temperature: 140 ° C., press time: 5 seconds), the sealing member of each layer is fused, Sealed to form a bag shape in which only the liquid injection part of each layer was opened.

  Furthermore, the produced electrolyte solution was injected into a portion where only the liquid injection portion of each layer was opened, and the sealing material portion was vacuum-sealed.

  After that, the power generation element is sandwiched between high-power terminals having a portion in which a part of an aluminum plate having a length of 130 mm × width of 80 mm × thickness of 100 μm that can cover the entire projection surface of the power generation element extends to the outside of the battery element projection surface. The aluminum laminate film was vacuum-sealed so as to cover it, and the entire power generation element was pushed at atmospheric pressure from both the upper and lower sides, thereby increasing the contact between the high voltage terminal and the power generation element. As a result, a stacked secondary battery as shown in FIG. 1 was obtained. This completes the description of matters common to the seven examples and comparative examples.

Example 1
A stacked secondary battery was fabricated in the same manner as described above (see FIGS. 2 and 3).

  Next, a method for manufacturing a divided electrode active material layer that has not been described in the above-described common matters will be described. That is, a negative electrode active material layer is formed by pressing a pattern mold between a negative electrode active material layer forming step of applying a high solid content negative electrode slurry to form a negative electrode active material layer and a drying step of drying the formed negative electrode active material layer. A negative electrode active material dividing step for dividing the negative electrode active material layer and a high resistance member installation step for providing a high resistance member having a higher electric resistance and ion permeability than the negative electrode active material layer in the divided portion of the negative electrode active material layer . Similarly, a positive electrode active material is formed by pressing a pattern mold between a positive electrode active material layer forming step of applying a high solid content positive electrode slurry to form a positive electrode active material layer and a drying step of drying the formed positive electrode active material layer. A positive electrode active material dividing step for dividing a layer into a plurality of layers and a high resistance member installing step for providing a high resistance member having higher electric resistance and ion permeability than the positive electrode active material layer in a portion where the positive electrode active material layer is divided are added. did.

  More specifically, the negative electrode active material layer and the positive electrode active material layer are respectively pressed by pressing the negative electrode active material layer and the positive electrode active material layer formed on the current collector using the press mold in the active material dividing step. Divided into two. Both the divided negative electrode active material layer and the divided positive electrode active material layer had a size of 36 mm × 70 mm. In this case, the divided part on the divided negative electrode active material layer side and the divided part on the divided positive electrode active material layer side were opposed to each other with the current collector interposed therebetween.

  In the high resistance member installation step, a high resistance member precursor solution in which 2 wt% carboxymethyl cellulose (CMC), 98 wt% alumina, and water as a viscosity adjusting solvent are mixed is applied and dried at the center position of the divided portion. Thus, a high resistance member of 60 μm × 20 mm was produced.

(Example 2)
After producing a divided negative electrode active material layer and a divided positive electrode active material layer in the same manner as in Example 1, a laminated secondary battery was produced in the same manner as described above (see FIGS. 4 and 5).

  In order to provide a high resistance member at the divided part, by applying and drying a precursor solution of a high resistance member in which carboxymethyl cellulose (CMC) is mixed with 2 wt%, alumina 98 wt% with an average particle size of 30 μm and water as a viscosity adjusting solvent. A high resistance member of 60 μm × 20 mm was produced.

(Example 3)
After producing a divided negative electrode active material layer and a divided positive electrode active material layer in the same manner as in Example 1, a laminated secondary battery was produced in the same manner as described above (see FIGS. 6, 7, and 8). ).

  The entire surface of the divided negative electrode active material and the entire surface of the divided positive electrode active material layer are coated with a precursor solution of a high resistance member in which 2 wt% carboxymethyl cellulose (CMC), 98 wt% alumina, and water as a viscosity adjusting solvent are mixed and dried. Thus, a high resistance member was produced.

Example 4
After producing a divided negative electrode active material layer and a divided positive electrode active material layer in the same manner as in Example 1, a laminated secondary battery was produced in the same manner as described above (see FIGS. 9, 10, and 11). ).

  A masking tape is affixed to the flat surface of the divided negative electrode active material layer that does not contact the current collector so that a high resistance member is not formed on the flat surface of the divided negative electrode active material layer that does not contact the current collector. A high resistance member of 60 μm × 70 mm was produced by applying a precursor solution of the high resistance member to the side surface of the long side opposite to the side where the part was present and drying. Similarly, masking tape is affixed to the flat surface of the divided positive electrode active material layer that does not contact the current collector so that a high resistance member is not formed on the flat surface of the divided positive electrode active material layer that does not contact the current collector. A high resistance member of 60 μm × 70 mm was produced by applying the precursor solution of the high resistance member to the side surface of the long side opposite to the side having the part and the divided part and drying.

(Example 5)
After producing a divided negative electrode active material layer and a divided positive electrode active material layer in the same manner as in Example 1, a laminated secondary battery was produced in the same manner as described above (see FIGS. 12 and 13).

  During the active material layer forming step of applying a high solid content negative electrode slurry to form an active material layer and the drying step of drying the formed negative electrode active material layer, both the division of the active material layer and the transfer of the high resistance member are performed. Added steps to perform. Similarly, the active material layer is divided and the high resistance member is separated between an active material layer forming step of applying a high solid content positive electrode slurry to form an active material layer and a drying step of drying the formed negative electrode active material layer. Added a process to transfer together.

  In this step, the precursor solution of the high resistance member is applied in advance to the surface of the press die, dried, and pressed using this press die, thereby dividing each of the negative electrode active material layer and the positive electrode active material layer. The transfer of a high resistance member of 25 μm × 70 mm was performed simultaneously.

(Example 6)
In the same manner as in Example 5, each division of the negative electrode active material layer and the positive electrode active material layer and the transfer of the high resistance member were simultaneously performed to produce a 10 μm × 70 mm high resistance member. Thereafter, a stacked secondary battery was fabricated in the same manner as described above (see FIGS. 14 and 15).

(Example 7)
After producing a divided negative electrode active material layer and a divided positive electrode active material layer in the same manner as in Example 4, a laminated secondary battery was produced in the same manner as described above (see FIGS. 16 and 17).

  However, a triangular mountain type press die was used for the press.

(Comparative example)
After the divided negative electrode active material layer and the divided positive electrode active material layer were produced in the same manner as in Example 8, a multilayer secondary battery was produced in the same manner as described above (see FIGS. 20 and 21).

  However, unlike Example 8, the high resistance member was not provided.

[Performance evaluation]
The stacked secondary batteries of Examples 1 to 7 and the comparative example were subjected to initial charge / discharge at 0.5 C for 5 hours (upper limit voltage of 4.2 V for each layer). Thereafter, a charge / discharge cycle test at 45 ° C. was performed 100 cycles, and the capacity measurement after storage was measured by 0.5C charge / discharge measurement. The results obtained are summarized in Table 1.

  "Rate characteristics" in the table is the discharge capacity when CC (Constant Current Constant Voltage) is charged at 4.2V and 1C for 2.5 hours and then CC (Constant Current) is discharged at 3C to 2.5V. These are expressed as relative values with the discharge capacity of the battery of the comparative example as 100.

  As shown in Table 1, in Example 1, the capacity deterioration after the cycle test is improved as compared with the comparative example. This is because it is possible to prevent electrical contact between the divided electrode active material layers that may occur with expansion and contraction when charging and discharging are repeated at a high temperature. Further, in the first embodiment, the high resistance member is provided only in a part of the divided part, so that the permeability of the electrolytic solution is good, and the deterioration of the rate characteristic is small compared to the comparative example.

  In Example 2, since the average pore diameter in the high resistance member is larger than the average pore diameter in the divided electrode active material layer, the electrolyte easily penetrates the high resistance member. In addition, the rate characteristic is lower than that of the first embodiment (the electrode characteristics are improved as compared with the first embodiment).

  In Example 3, since the high resistance members are arranged on the entire surfaces of the divided negative electrode active material layer and the divided positive electrode active material layer, the divided electrode active material layer of one bipolar electrode adjacent in the stacking direction, and the stacking direction The probability of occurrence of an internal short circuit between the other bipolar electrode adjacent to the divided electrode active material layer decreases. Further, the stacking direction distance between the divided negative electrode active material layer of one bipolar electrode adjacent in the stacking direction and the split positive electrode active material layer of the other bipolar electrode adjacent in the stacking direction can be made constant. Therefore, the reaction in the active material layer easily proceeds uniformly. As a result, as shown in Table 1, the capacity retention rate after the cycle test is improved as compared with Examples 1 and 2.

  In Example 4, since there is no high resistance member between the divided negative electrode active material layer of one bipolar electrode adjacent in the stacking direction and the divided positive electrode active material layer of the other bipolar electrode adjacent in the stacking direction, The capacity density of the battery can be increased. As a result, as shown in Table 1, the capacity retention rate after the cycle test is the same as that of Example 3.

  In Example 5, since the electrolyte solution can diffuse through the voids, the electrolyte solution easily penetrates into the divided negative electrode active material layer and the divided positive electrode active material layer near the current collector, so that the electrode characteristics are improved. To do. As a result, although not as much as in the first and second embodiments, as shown in Table 1, the decrease in rate characteristics is small.

  In Example 6, by making the horizontal width of the void portion larger than the average pore diameter of the divided negative electrode active material layer or the divided positive electrode active material layer, the electrolyte solution penetrates the current collector side through the void portion. Since it becomes easy, an electrode characteristic improves. As a result, as shown in Table 1, the reduction in rate characteristics can be made smaller than in Example 5.

  Next, a method for manufacturing a bipolar electrode will be described. Here, a bipolar electrode manufacturing method using a relatively highly solid electrode mixture (negative electrode slurry or positive electrode slurry) will be described first, and then the bipolar electrode manufacturing method of the present invention will be described.

  In the first embodiment of the bipolar electrode manufacturing method, an electrode containing a solvent prior to the drying step is shortened by reducing the time required for the drying step by applying a relatively high-solid electrode kneaded material to the current collector. A pressing step of pressing the kneaded product is performed.

  FIG. 37 is a schematic configuration diagram of an electrode manufacturing apparatus 100 used when manufacturing an electrode of a stacked secondary battery. The electrode manufacturing apparatus 100 includes a transport device 110, a kneading device 120, a coating device 130, a press device 140, and a drying device 150. The electrode manufacturing apparatus 100 applies the electrode kneaded material 121 kneaded by the kneading device 120 to the surface of the current collector 4 conveyed by the conveying device 110 by the coating device 130, and the bulk density of the electrode kneaded material 121 by the press device 140. After the adjustment, the electrode is manufactured by drying with the drying device 150.

  Hereinafter, each apparatus which comprises the electrode manufacturing apparatus 100 is explained in full detail. The transport device 110 includes a take-up roll 111, a take-up roll 112, and a support roll 113. The transport device 110 transports the thin film-like current collector 4 from the take-up roll 111 to the take-up roll 112 by a roll-to-roll method.

  The current collector 4 is wound around the take-up roll 111. The take-up roll 111 includes a braking mechanism 115, and the rotation of the take-up roll 111 is appropriately restricted by the braking mechanism 115, and a predetermined tension is applied to the current collector 4. The take-up roll 112 is rotationally driven by the drive motor 116 and takes up the current collector 4 taken up from the take-up roll 111. A plurality of support rolls 113 are provided in the current collector conveyance path between the take-up roll 111 and the take-up roll 112, and hold the lower surface of the current collector 4 being conveyed.

  The kneading apparatus 120 is a biaxial kneader, in which a slurry is adjusted to a predetermined viscosity [Pa · s] at a shear rate (shear rate) [1 / sec] by uniformly dispersing an electrode material in a solvent. This is an apparatus for manufacturing the electrode kneaded material 121. The kneading apparatus 120 uniformly disperses the electrode material in the solvent while heating so that the temperature of the manufactured electrode kneaded material 121 is 40 [° C.] to 60 [° C.]. The kneading apparatus 120 is not limited to the twin-screw kneader, and for example, a planetary mixer or a kneader may be used. Here, the amount of the solvent is adjusted so that the electrode kneaded material 121 becomes a highly solid kneaded material. Specifically, the weight percent (wt%) of the solvent is adjusted to be 10 [wt%] to 30 [wt%] with respect to the electrode material.

  Thus, the electrode kneaded material 121 applied to the current collector 4 is made highly solid, so that the electrode kneaded material 121 can be pressed before drying. In addition, since the amount of the solvent in the electrode kneaded product is relatively reduced by making it highly solid, the drying time can be shortened.

  In general, an electrode is formed by applying a relatively low solid slurry-like electrode kneaded material obtained by kneading an electrode material and a solvent to a current collector, and then volatilizing the solvent in the electrode kneaded material. It is manufactured through a drying process, and a pressing process in which the electrode material is compressed to adjust its bulk density (thickness). However, when the pressing step is performed after the drying step, the electrode material after all the solvent in the electrode kneaded product is volatilized is pressed. Therefore, since there is no solvent, the fluidity of the electrode active material particles constituting the electrode material is reduced, so even if the electrode material is pressed, a relatively large gap remains in the electrode material, resulting in a decrease in battery performance. End up. In addition, when a relatively low solid electrode kneaded material is applied to the current collector, the amount of solvent in the electrode kneaded material is relatively increased, and the time required for the drying process is increased. As the time required for the drying process becomes longer, it is necessary to lengthen the drying furnace length, and the amount of capital investment increases. Therefore, the amount of the solvent was adjusted so that the electrode kneaded material 121 became a highly solid kneaded material.

  The highly solid kneaded material referred to in the present embodiment has a viscosity of 10 [Pa · s] to 1000 [Pa · s] in a shear rate range of 50 [1 / sec] to 4000 [1 / sec]. The one in the range. Among these, it is preferable that the viscosity in the range of 200 [1 / sec] to 4000 [1 / sec] is in the range of 10 [Pa · s] to 1000 [Pa · s].

  In the case of producing a positive electrode slurry as an electrode kneaded product, a positive electrode active material, a conductive auxiliary agent, and a binder (binder) as electrode materials are charged into the kneading apparatus 120, and these are uniformly dispersed in a solvent. . In the case of producing a negative electrode slurry as an electrode kneaded product, a negative electrode active material, a conductive auxiliary agent, and a binder as an electrode material are charged into the kneading apparatus 120, and these are uniformly dispersed in a solvent.

  The coating device 130 is a device that applies the electrode kneaded material 121 manufactured by the kneading device 120 to the surface of the metal foil 114, and includes a gear pump 131 and a slit die 132. The gear pump 131 is provided between the kneading device 120 and the slit die 132, pressurizes the electrode kneaded material 121 manufactured by the kneading device 120, and sends it to the slit die 132. The slit die 132 discharges the electrode kneaded product 121 through the slit 132a formed at the tip, and applies the electrode kneaded product 121 to the surface of the current collector 4 being conveyed. The slit die 132 applies the electrode kneaded material 121 at a predetermined interval in the conveying direction of the current collector 4.

  The press device 140 is a device that is provided in the metal foil conveyance path on the downstream side of the coating device 130 and presses the electrode kneaded material 121, and includes a roller press 141 and a vacuum pump 142. The roller press 141 includes a first roller 141 a that directly presses the electrode kneaded material 121 from the front surface side of the current collector 4, and a first roller 141 a that presses the electrode kneaded material 121 from the back surface side of the current collector 4 via the current collector 4. 2 rollers 141b. The roller press 141 sandwiches and compresses the electrode mixture 121 between the first roller 141a and the second roller 141b. At this time, the solvent exuded from the electrode kneaded material 121 during compression is passed through the roller surface 143 while maintaining the roller surface 143 at a predetermined temperature so that the electrode kneaded material 121 does not adhere to the roller surface 143 of the first roller 141a. The electrode kneaded material 121 is adjusted to have a predetermined bulk density by sucking. For this purpose, the first roller 141a is provided with a negative pressure chamber 144, a communication hole 145, and a heater 146.

  The negative pressure chamber 144 is a space having a predetermined volume formed inside the first roller 141a. The negative pressure chamber 144 is connected to the vacuum pump 142 and is depressurized by the vacuum pump 142.

  The communication hole 145 is a passage that communicates the negative pressure chamber 144 with the roller surface 143 of the first roller 141a. The solvent that has oozed out of the electrode kneaded product 121 through the communication hole 145 is sucked into the negative pressure chamber 144 that has been decompressed and removed (removed under reduced pressure).

  The heater 146 is provided inside the first roller 141a and heats the roller surface 143 of the first roller 141a. The roller surface 143 is heated by the heater 146 so that the temperature of the roller surface 143 falls within the range of 25 [° C.] to 60 [° C.].

  The drying device 150 is a hot air drying furnace, and is provided in the current collector conveyance path on the downstream side of the pressing device 140. The drying device 150 is a device that blows hot air to the electrode kneaded material 121 to volatilize and remove the solvent in the electrode kneaded material 121 and dry the electrode kneaded material 121.

  This concludes the description of the electrode manufacturing method using a relatively highly solid electrode kneaded product.

  Now, in the first embodiment of the method for manufacturing the bipolar electrode 3, as shown in FIG. 37, the second press device 160 (active material dividing step) and the second press device 140 are arranged between the press device 140 and the drying device 150. Application device 170 (high resistance member installation step). Here, the 2nd press apparatus 160 is an apparatus for dividing | segmenting an electrode active material layer for Examples 1-6, and the 2nd coating apparatus 170 is high resistance to a division | segmentation site | part for Examples 1-6. It is an apparatus for providing a member.

  Since the processing performed in the second press device 160 and the second coating device 170 differs between the first to fourth embodiments and the fifth and sixth embodiments, first, in the case of the first to fourth embodiments, the second press device 160 is used. And the process performed with the 2nd coating device 170 is demonstrated with reference to FIG. However, here, the case of Example 3 is used as a representative.

  In the pressing step shown in FIGS. 38A and 38B, the electrode active material layer 21 formed on the current collector 4 is pressed by using a press die 81, so that the electrode active material layer 21 is divided into two. To divide. The press die 81 has a protrusion 82 for forming the divided portion 25, and the protrusion 82 pushes away a part of the electrode active material layer 21, whereby the divided electrode active material layers 22, 23 and the divided portion 25 are formed. It is formed. Here, FIG. 38A shows a state before pressing with the press die 81, and FIG. 38B shows a state after pressing with the press die 81.

  In the coating step shown in FIG. 38 (c), by applying a precursor solution of a high resistance member having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 to the divided portion 25 generated by pressing. Then, the high resistance member 28 having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is produced. In FIG. 38 (c), the high resistance member 28 is also provided on the flat surfaces 22 d and 23 d on the side not in contact with the current collector 4. To prevent the high resistance member 28 from being provided on the flat surfaces 22d and 23d as in the fourth embodiment, the flat surfaces 22d and 23d may be masked.

  Next, processing performed in the second press device 160 and the second coating device 170 in the case of Examples 5 and 6 will be described with reference to FIG. However, the case of Example 5 is representative here.

  In the pressing / coating process shown in FIGS. 39A and 39B, the pressing process and the coating process are performed simultaneously. That is, in FIG. 39A, a precursor solution of a high resistance member having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is applied in advance to the outer peripheral surface of the protrusion 82 of the press die 81 and dried. 3 shows a state in which a precursor 83 of a high resistance member having higher electric resistance and ion permeability than the divided electrode active material layers 22 and 23 is formed.

  FIG. 39B shows a state after pressing using the press die 81 forming the precursor 83, and after the press die 81 is pulled out, the electric power is supplied from the divided electrode active material layers 22 and 23. High resistance members 32 and 33 having high resistance and ion permeability are formed on the end faces of the divided electrode active material layers 22 and 23, and voids 34 are formed between the two high resistance members 32 and 33. Yes.

  In the embodiment, the thickness of the high resistance member having higher ion resistance and higher ion resistance than that of the divided electrode active material layer is described as being equivalent to the thickness of the divided electrode active material layer. The thickness of the high resistance member having high ion permeability is preferably smaller than the thickness of the divided electrode active material layer. This is because, although the high resistance member has ion permeability, in other words, is porous, it interferes with the movement of ions, so that the thinner the high resistance member, the higher the ion diffusibility.

1 stack (stacked battery)
3 Bipolar Electrode 4 Current Collector 21 Electrode Active Material Layer 22, 23 Divided Electrode Active Material Layer 25 Divided Sites 27, 27 ′ High Resistance Member 28, 29, 32, 33 High Resistance Member 34, 34 ′ Gap 35 High Resistance Member 41 Negative electrode active material layer 42, 43, 44 Split negative electrode active material layer 45 Positive electrode active material layer 46, 47, 48 Split positive electrode active material layer 49, 50, 51, 52 Split part 53, 54, 55, 56 High resistance member DESCRIPTION OF SYMBOLS 100 Electrode manufacturing apparatus 120 Kneading apparatus 130 Coating apparatus 140 Press apparatus 150 Drying apparatus 160 2nd press apparatus 170 2nd coating apparatus

Claims (10)

An electrode in which an active material layer divided into a plurality of current collectors is formed,
An electrode comprising: a high-resistance member having higher ion resistance and higher ion resistance than an active material layer between two adjacent active material layers.   The electrode according to claim 1, wherein an average pore diameter in the high resistance member is larger than an average pore diameter of the active material layer.   The electrode according to claim 1, wherein the high resistance member is provided at all between the two adjacent active material layers. The high resistance members are respectively disposed on all end faces of the adjacent two divided active material layers,
The electrode according to claim 1, wherein a gap is provided between the high resistance members arranged.   The electrode according to claim 4, wherein a distance between the voids is larger than an average pore diameter of the active material layer. The electrode is a bipolar electrode that forms a negative electrode active material layer on one surface of a current collector and a positive electrode active material layer on the other surface;
The number of the negative electrode active material layer and the positive electrode active material layer divided is the same number,
The divided negative electrode active material layer and the divided positive electrode active material layer face each other across the electrolyte,
3. The electrode according to claim 1, wherein a distance between two adjacent divided negative electrode active materials is smaller than a distance between two adjacent divided positive electrode active material layers.   A battery using the electrode according to any one of claims 1 to 6. An active material layer forming step of forming an active material layer by applying a high solid content slurry to a current collector;
An active material dividing step of pressing a pattern mold on the formed active material layer to divide the active material layer into a plurality of parts,
And a high resistance member installation step of providing a high resistance member having a higher electric resistance and ion permeability than the active material layer in a portion where the active material layer is divided.   The method for manufacturing an electrode according to claim 8, wherein in the high resistance member installation step, a solution containing the high resistance member is applied to a portion where the active material layer is divided.   In the active material dividing step and the high-resistance member installing step, the active material layer is divided and the high-resistance member is transferred by pressing a pattern mold having the high-resistance member formed on the surface onto the active material layer. The method for producing an electrode according to claim 8.

Images