KR20140016180A - Laminate structural cell - Google Patents

Abstract

The present invention is to provide a stack-structure cell including a resin layer between an electrode and a separator capable of preventing melting imbalance among resin layers inside and outside the stacking direction and reducing the difference of ion permeability among the resin layers. The stack-structure cell has a stack of three or more single cell layers which have an electrolyte layer including a cathode, an anode, and a separator and in which the cathode and the anode are put into the electrolyte layer. Between at least one among the cathode and the anode and the separator, a resin layer which is formed by attaching at least one among the cathode and the anode and the separator exists. The resin layer includes a coating part and a non-coating part. The area (if multiple coating parts, the average area of the coating parts) of the coating part at the center is greater than the area of the edge.

Description

Laminated Structure Battery {LAMINATE STRUCTURAL CELL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated structure battery, which is one kind of electrical device that works externally by electrons and ions acting electrochemically. Specifically, it is related with the laminated structure battery represented by the lithium ion secondary battery of a laminated type (laminated structure).

In recent years, in order to cope with air pollution and global warming, reduction of the amount of carbon dioxide is eagerly desired. In the automobile industry, there is an expectation that reduction of carbon dioxide emission by introduction of an electric vehicle (EV) or a hybrid electric vehicle (HEV) is expected, and development of the motor drive secondary battery which has taken advantage of these practical use is actively performed.

In motor drive secondary batteries, it is required to have extremely high output characteristics and high energy as compared to civilian lithium ion secondary batteries used in mobile phones, notebook computers and the like. Therefore, the lithium ion secondary battery which has the highest theoretical energy among all the batteries attracts attention, and development is currently progressing rapidly.

In general, a lithium ion secondary battery includes a positive electrode in which a positive electrode active material or the like is coated on both surfaces of a positive electrode current collector using a binder, and a negative electrode in which the negative electrode active material or the like is coated on both sides of the negative electrode current collector using a binder. It is connected through and is accommodated in a battery exterior material. For example, Patent Document 1 discloses a battery group (power generation element) in which a positive electrode and a negative electrode are alternately stacked via a separator in an outer case of a laminate sheet, and after injecting an electrolyte solution, an outer edge of the laminate sheet is placed. Lithium ion secondary batteries (laminated structure batteries) are described which are sealed under a pressurized environment.

Japanese Patent Publication No. 2009-211937

However, in the conventional laminated structure lithium ion secondary battery (laminated structure battery) such as patent document 1, in order to prevent the short circuit by the thermal contraction of a separator, the outer edge of the laminated sheet which is the above-mentioned exterior materials is pressurized in a certain environment. Sealing only under was insufficient.

MEANS TO SOLVE THE PROBLEM In order to prevent the short circuit by the thermal contraction of a separator in a laminated structure battery, this inventor provided a resin layer between an electrode-separator, heat-fused (partially melted) a resin layer by applying a load between electrodes by hot press, The construction method was constructed to connect the electrode-separator.

However, in a laminated structure battery, it is necessary to heat-press (hot press) from the up-down direction of the power generation element (battery group) of a laminated structure. Therefore, in a large-sized laminated structured battery such as a laminated structured battery, particularly a vehicle mounted battery, there is a difference in the amount of heat received at the short side and the center side of the laminated structured battery, and the rate of melting of the resin layer at the center portion and the end portion in the lamination direction It turned out that the fluctuation | variation generate | occur | produced in (refer FIG. 2). As a result, it turned out that there exists a problem that deterioration is accelerated | stimulated by the difference in the ion permeability in the said resin layer in the center part and the edge part of a lamination direction (refer the Example of Table 2 and a comparative example).

Accordingly, an object of the present invention is to prevent fusion unevenness of the resin layers in the inner (inner) and outer (outer) directions of the lamination direction in a laminated structure battery having a resin layer between the electrode and the separator, thereby preventing ions of the respective resin layers. It is an object of the present invention to provide a laminated structure battery capable of reducing the difference in permeability.

In the laminated structure battery of the present invention, in a laminated structure battery having a resin layer having a coating portion and an uncoated portion between electrodes and separators, the area of a single coating portion is centered in the stacking direction (thickness direction of the battery). It is characterized by the point of <side.

In the present invention, by increasing the area of a single coating portion of the resin layer on the short side of the laminated structure battery and reducing the area along the center in the stacking direction, the short side with high hot press temperature and the center side with low hot press temperature In, the melt rate of each resin layer can be uniformly aligned. Thereby, the reaction distribution nonuniformity for every single cell layer (monocell) can be prevented, and the durability of the whole laminated structure battery can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional schematic drawing which shows the basic structure of the laminated (flat type) nonaqueous electrolyte lithium ion secondary battery which is one typical embodiment of a laminated structure battery.
FIG. 2 is a partial cross-sectional view of a power generating element of the laminated structure battery of FIG. 1, which schematically illustrates how heat is transmitted when a hot press (hot press) is performed from an up and down direction of the power generating element of the laminated structure battery. FIG. to be.
FIG. 3: (A) is a top view which shows the state which provided the stripe coating part in the electrode surface. 3 (B) and 3 (C) are plan views illustrating a state in which dot coating portions are provided on the electrode surface.
4 is a perspective view showing the appearance of a flat lithium ion secondary battery as a representative embodiment of a secondary battery.
FIG. 5 is a schematic cross-sectional view schematically showing a state in which the laminated structure battery produced in the example is hot pressed (hot pressed) using a pressing jig having a heat press function.

In the laminated structure battery of this embodiment, a resin layer formed by adhering therebetween is also present between at least one of the parts and the separator, and the resin layer has a coating portion and an uncoated portion. In addition, in this embodiment, the area of the single coating part which comprises a coating part (when a coating part consists of several single coating part, each is set as the average value of the area of a single coating part) is center side in a lamination direction. It is characterized by being single sided. Here, the laminated structure battery refers to a battery having a laminated structure in which at least three single cell layers having an electrolyte layer including at least a positive electrode, a negative electrode, and a separator and facing the positive electrode and the negative electrode through the electrolyte layer are laminated. By setting it as such a structure, the effect of said invention can be exhibited. Further, unlike changing the melting point of the coating portion of the resin layer on the short side and the center side, the same material can be used for the coating portion of the resin layer, thereby simplifying the production process.

As a preferable embodiment of a laminated structure battery, although a laminated (laminated structure) nonaqueous electrolyte lithium ion secondary battery is demonstrated, it is not limited only to the following embodiment. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

The lithium ion secondary battery of the laminated type (laminated structure) of the present embodiment is particularly preferably applied to a large-sized battery such as a vehicle-mounted battery, but is not limited to the size and use of the battery. It can be applied to a lithium ion secondary battery of a laminated structure used for any size and use conventionally known.

There is no restriction | limiting in particular also when classifying the laminated ion (laminated structure) lithium ion secondary battery of this embodiment in the form of electrolyte. For example, it can be applied to both of a liquid electrolyte type battery in which a nonaqueous electrolyte solution is impregnated in a separator, a polymer gel electrolyte type battery also called a polymer battery, and a solid polymer electrolyte (all solid electrolyte) type battery. In this embodiment, also about a polymer gel electrolyte and a solid polymer electrolyte, what impregnated these polymer gel electrolyte and a solid polymer electrolyte in the separator is used.

The lithium ion secondary battery of the laminated type (laminated structure) of the present embodiment may be a battery having an electrode structure other than the bipolar type (internal parallel connection type) or a battery having an electrode structure of the bipolar type (internal series connection type). do.

In the following description, a lithium ion secondary battery of a laminated type (laminated structure), which is not a bipolar type (internal parallel connection type), will be described with reference to the drawings, but the present invention should not be limited thereto.

1 is a schematic diagram showing a basic configuration of an embodiment of a laminated (flat) nonaqueous electrolyte lithium ion secondary battery (hereinafter, simply referred to as a "laminated structure battery"). As shown in FIG. 1, the laminated structure battery 10 of this embodiment has the structure sealed in the inside of the battery exterior material 29 which is the exterior of the substantially rectangular power generation element 21 which a charging / discharging reaction actually progresses. . Here, the power generation element 21 has a structure in which a positive electrode, a separator (electrolyte layer) 17 containing an electrolyte, and a negative electrode are laminated. The positive electrode has a structure in which the positive electrode active material layer 13 is disposed on both surfaces of the positive electrode collector 11. The negative electrode has a structure in which the negative electrode active material layer 15 is disposed on both surfaces of the negative electrode collector 12. In addition, in this embodiment, between the separator (electrolyte layer) 17 and the negative electrode (active material layer 15), the resin layer 18 formed by adhering (for example, thermal fusion etc.) between these is carried out. This is also arranged. In addition, the resin layer 18 formed by adhering between the separator (electrolyte layer) 17 and the positive electrode (active material layer 13) between the separator (electrolyte layer) 17 and reversely arrange | positions the resin layer 18 from FIG. This may be arranged. Further, both of the separator (electrolyte layer) 17 and the negative electrode (active material layer 15) and between the separator (electrolyte layer) 17 and the positive electrode (active material layer 13) are both The resin layers 18 formed by adhering to each other may be arranged.

Specifically, one positive electrode active material layer 13 and the negative electrode active material layer 15 adjacent thereto are opposed to each other via the electrolyte layer 17 and the resin layer 18, and the negative electrode, the resin layer, the electrolyte layer, and the like. The positive electrodes are stacked in this order. As a result, the adjacent positive electrode, the electrolyte layer, the resin layer, and the negative electrode constitute one single cell layer (single cell) 19. Therefore, it can also be said that the laminated structure battery 10 of this embodiment has a structure which is electrically connected in parallel by plural unit cell layers (single cells) 19 being laminated | stacked. In addition, in the lithium ion secondary battery (not shown) of the bipolar type (internal series connection type) laminated type (stacked structure), it can also be said that it has a structure which is electrically connected in series by stacking multiple single cell layers (single cells). have.

In addition, although the positive electrode active material layer 13 is arrange | positioned only to one side in the outermost layer positive electrode electrical power collector which is located in both outermost layers of the power generation element 21, the active material layer may be provided in both surfaces. That is, the current collector having the active material layer on both sides may be used as the current collector of the outermost layer, instead of the current collector dedicated only to the outermost layer provided with the active material layer only on one side. In addition, the arrangement of the positive electrode and the negative electrode is reversed from that in FIG. 1, so that the outermost negative electrode current collector is positioned at both outermost layers of the power generation element 21, and the negative electrode active material layer is disposed on one or both surfaces of the outermost negative electrode current collector. It may be arranged.

In the present embodiment, the electrode (positive electrode or negative electrode) includes a freestanding electrode. The freestanding electrode ensures shape even when there is no metal foil (current collector). In other words, the self-standing electrode (self-supporting structure) is structurally (or rigidly), and can form the shape only by the active material layer without the metal foil (current collector). However, even if it is a self-supporting electrode (independence structure), as an electrode element, an electrical power collector (however, in addition to metal foil, it may be a metal vapor deposition film, plating thin film, metal wiring, etc. which are lower in mechanical strength than a metal foil, and cannot ensure shape) And an active material layer are required. The self-supporting electrode defined above has an active material layer (positive electrode active material layer, negative electrode active material layer) and a current collector (positive electrode current collector, negative electrode current collector) formed directly on one side of the active material layer. The active material layer contains a porous skeleton and an active material (positive electrode active material, negative electrode active material) held in the pores of the porous skeleton.

In this specification, when describing as "a current collector," it may refer to both a positive electrode electrical power collector and a negative electrode electrical power collector, may point to only one side, and may point to the bipolar electrode electrical power collector of a bipolar battery. . Similarly, when describing as "active material layer", it may refer to both a positive electrode active material layer and a negative electrode active material layer, and may point to only one side. Similarly, when describing as "active substance", it may refer to both a positive electrode active material and a negative electrode active material, and may point to only one side. Similarly, when describing as "electrode", it may refer to both a positive electrode and a negative electrode, and may point to only one side.

One of the positive electrode current collector tab (positive current collector plate) 25 and the negative electrode current collector tab (negative current collector plate) 27 connected to each electrode (positive electrode and negative electrode) is provided in the positive electrode current collector 11 and the negative electrode current collector 12. The end ends of are respectively installed. Further, the other end portions of the positive electrode current collector tab 25 and the negative electrode current collector tab 27 are fitted to the ends of the battery exterior member 29 and have a structure that is led out of the battery exterior member 29. The positive electrode current collector tab 25 and the negative electrode current collector tab 27 are respectively interposed with an electrode terminal lead (positive electrode terminal lead and negative electrode terminal lead) (not shown), and the positive electrode current collector 11 of each electrode and The negative electrode current collector 12 may be provided by ultrasonic welding, resistance welding, or the like.

Moreover, as a characteristic structure of the laminated structure battery 10 of this embodiment, the resin layer 18 has a coating part and an uncoated part. In addition, the area of the single coating portion constituting the coating portion (when the coating portion is composed of a plurality of single coating portions, each of which is the average value of the areas of the single coating portion) is the center side <single side in the stacking direction. It is characterized by.

FIG. 2 is a partial cross-sectional view of a power generating element of a laminated structure battery, and is a diagram schematically showing how heat is transmitted when hot pressing (hot press) is performed from the up and down direction of the power generating element of the laminated structure battery. In addition, the arrow in a figure shows typically how heat is transmitted. As shown in FIG. 2, heat is propagated from the top and bottom (end) to the center (center side) of the power generation element 21 by hot pressing by the apparatus 20 for hot pressing the power generation element 21 from the top and bottom. do. Therefore, it heats up quickly from the apparatus 20 on the short side of a lamination direction, and becomes high temperature in a short time (= easy to melt). On the other hand, in the center part of the lamination direction, it takes time for heat transfer from the apparatus 20, and, within the time of heat press processing, a hot press does not become high temperature to the same level as a single side (= in a state which is difficult to melt). It ends.

Therefore, the area (average value) of the single coating part which comprises the coating part of the resin layer was made into the center side (= single side) (single coating part which comprises the coating parts of all the resin layers) in the lamination direction to the same area (average value). In this case, there is a difference in the amount of heat from the single side and the middle side. Therefore, fluctuation | variation arises in the melt rate of a resin layer in a lamination direction, and there exists a possibility that melting and adhesion | attachment of a resin layer may become inadequate in the center side of a lamination direction. As a result, a separator heat-shrinks in abnormal heat generation etc., the edges of opposing electrodes may contact, and there exists a possibility of causing a micro short circuit. Here, the area (average value) where the single coating part which comprises the coating part of all the resin layers has the same area (average value) shall say the area (average value) of the single coating part of the single side with respect to the center side within 1 +/- 0.03 times. This takes into account the range in which manufacturing errors and generated problems are about the same.

In addition, when the area (average value) of the single coating part which comprises the coating part of the resin layer is set to the center side (= single side) (single coating part which comprises the coating parts of all resin layers) in the lamination direction, it is the same area (average value). The following problems may also arise. That is, when lengthening the time of hot-pressing process until the melting | fusing and adhesion | attachment of the center part of a lamination direction is sufficient, a load is applied to the short side of a lamination direction in a high temperature state for a long time. Therefore, there exists a possibility that it may melt too much and it may become difficult for each single coating part which comprises the coating part of a resin layer to maintain a desired thickness. As a result, the size of the conductive paths (path lengths through which Li ions diffuse) on the center side and the ends changes, the ion permeability changes on the center side and the end, and the ion permeability (= inter-electrode resistance) is uneven in the stacking direction. There is a fear of this.

Therefore, the structure of this embodiment mentioned above, ie, the resin layer has a coating part and an uncoated part, and the area of the single coating part which comprises a coating part is center side <short side in a lamination direction (thickness direction of a battery). To be In addition, when the coating part consists of several single coating part, each area of a single coating part shall be made into the average value of the area of a single coating part, respectively. That is, the resin layer is formed of a dot or stripe-shaped coating part and an uncoating part, and the area of the single coating part is increased as the resin layer on the single side of the laminated structure battery becomes larger, and the area of the single coating part on the resin layer on the center side (dot) Area or stripe area). By setting it as such a structure, the area | region (average value) of a single coating part can be reduced as it goes toward the lamination direction center side of a laminated structure battery, the melt rate of each resin layer can be aligned uniformly, and the melt nonuniformity of a lamination direction is removed. It can prevent. As a result, the reaction distribution nonuniformity for every unit cell layer (monocell) can be prevented, and the durability of the whole laminated structure battery can be improved. In this configuration, as shown in Fig. 2, when hot-pressing the power generating element 21 by the apparatus 20 for hot pressing from the top and the bottom, the hot press temperature is high and the long side is long, and hot On the center side where the press temperature is low and the time is short, the melt rate of each resin layer can be uniformly aligned. Thereby, it can melt | dissolve and adhere suitably (more uniformly) within predetermined | prescribed hot press time, without changing the material and thickness of each resin layer, and ion permeability in the said resin layer in the center part and the edge part of a lamination direction Can also reduce the difference. That is, even if the temperature of a hot press is low in the center side of a lamination direction, it can adhere at the same timing as an edge part. As a result, it is excellent in the point that the reaction distribution nonuniformity for every unit cell layer (single cell) 19 can be prevented, and the durability of the whole laminated structure battery 10 can be improved significantly (refer capacity retention rate of Table 2 of an Example). . In addition, in this embodiment, the area | region of the single coating part which comprises the coating part of a resin layer is made into the center side <end side in a lamination direction, without changing the material and thickness of the coating part of a resin layer. Therefore, unlike changing melting | fusing point from the short side and the center side, the same material is used for the coating part of the resin layer in the short side and the center side, and it is necessary to adjust the thickness of the resin layer (coating part) in the short side and the center side. It is also excellent in that the production process can be simplified. That is, in the present embodiment, for example, only by applying a screening print on a masking sheet in which a resin layer forming material is opened to a desired dot size, the area (dot area or stripe area) of a desired single coating portion is adjusted ( Excellent in that it can be changed). In addition, although the single coating part mentioned here does not have description in particular, For example, in FIG.3 (B), each one of each dot-shaped coating part formed in four corners corresponds. That is, in the case of Fig. 3B, four (four corners) single coating portions (dots) exist. In the case of Fig. 3A, a single coating portion (stripe-shaped) is present (two at equal intervals). In the case of FIG. 3C, there are 12 single coating portions (at equal intervals) in the shape of dots.

In addition, in this embodiment, it is preferable to make the total area in the surface of a coating part the same in a center side and a short side in a lamination direction. This can be formed, for example, by applying the resin layer forming material by screening printing on a masking sheet that is opened to have a desired dot size and a desired number of dots per cm 2. Thereby, it is excellent in the point which the adhesive force of each resin layer can be aligned, and can make it adhere | attach more uniformly with the same adhesive force (adhesion area) of the short side and the center side. Here, that the total area in the surface of the coating part is the same on the center side and the short side in the stacking direction, should be within the range of 1 ± 0.1 times the total area in the surface of the coating part on the short side with respect to the center part. Preferably it is in the range of 1 ± 0.05 times. This takes into account the range in which manufacturing errors and obtained effects become equal.

In this embodiment, when the coating part consists of a plurality of single coating parts, when the coating part consists of a plurality of single coating parts, (1) each of the area of a single coating part may have the same area and the same cross-sectional shape. It may be possible. (2) Each may make the area of a single coating part the same area, and each may have different cross-sectional shapes of a single coating part. The cross-sectional shape in this case (cross-sectional shape at the time of cutting in the direction perpendicular to the thickness direction) is not particularly limited. In the case of a dot shape, circular shape ((B), (C) of FIG. 3), ellipse shape, teardrop shape, polygon shape (triangle shape, square shape, pentagon shape, hexagon shape etc.), ring shape, character shape , Numeric shape, irregular shape, and the like. In the case of a stripe shape, a rectangular shape (rod shape; Fig. 3A), a wavy shape, an uneven shape, a sawtooth shape, a lattice shape, an inclined lattice shape (rhombus shape), a continuous loop shape, an irregular shape, and the like can be given. Can be. When cross-sectional shape differs, you may select another arbitrary form suitably from the form of a dot shape. Moreover, you may select another arbitrary form suitably from the stripe form. Moreover, you may select suitably other arbitrary forms from the form of a dot shape and stripe shape (that is, the combination of the shape of a dot shape and a stripe shape may be sufficient). In addition, each of (3) may have a different surface area of a single coating portion and the same cross-sectional shape (including a similar shape). (4) You may make it differ in the area and cross-sectional shape of a single coating part, respectively. The cross-sectional shape in this case is the same as the cross-sectional shape of said (2). In addition, in the case of said (3) and (4), the area of a single coating part is made into the average value of the area of each single coating part as mentioned above. Further, from the viewpoint of easy quality control by visual inspection or simple dimensional inspection by an extraction test or the like, in the case of the above (1), (2), particularly preferably the above (1), the cross-sectional shape is not complicated. The thing (in the case of a dot shape, a round shape, a square shape, a stripe shape, a rectangular shape, etc.) is preferable. Moreover, also in all of these (1)-(4), it is preferable that the total area in the surface of a coating part is the same on the center side and the short side in a lamination direction. This is because it is excellent in the point that the adhesive force of each resin layer can be aligned, and a single side and a center side can be adhere | attached more uniformly with the same adhesive force (adhesion area).

Here, as an area | region where the area difference of the single coating part of the center side (middle side, inner side, or center part) and the short side (outer side, outer side, or end part) of the lamination direction of the resin layer 18 is suitable, the objective of this embodiment is achieved and desired. It can be effective. That is, the area (average value) of the single coating part of the resin layer on the single side is increased, and the area thereof is decreased as it is directed toward the center side, and the hot side has a high hot press temperature and a long time, and a short hot press temperature and a short time. The melt rate of each resin layer can be uniformly aligned at the center side. Thereby, the reaction distribution nonuniformity for every unit cell layer (single cell) 19 can be prevented, and the durability of the whole laminated structure battery 10 can be improved.

Although it depends also on the lamination | stacking number of the single cell of a battery, and the magnitude | size of an electrode specifically, what is necessary is just the area (average value) of the single coating part of the resin layer of the single side of a lamination direction larger than the area (average value) of the single coating part of the resin layer of a center part. . Preferably, the area (average value) of the single coating portion of the resin layer on the single side in the stacking direction is preferably 1.1 to 4.0 times larger than the area (average value) of the single coating portion of the resin layer on the central portion, more preferably 1.2 to 3.0. It is desirable to be twice as large. If the area of the single coating portion of the resin layer on the single side in the stacking direction is 1.1 times or more, preferably 1.2 times or more larger than the area of the single coating portion of the resin layer on the central portion, depending on the number of laminations, The resin layer can also be sufficiently bonded. Thereby, it can prevent that melt nonuniformity arises in a lamination direction. As a result, the above objects and effects can be sufficiently achieved. On the other hand, if the area of the single coating part of the resin layer on the single side in the stacking direction is 4.0 times or less, preferably 3.0 times or less than the area of the single coating part of the resin layer on the central portion, the melt rate of each resin layer is increased. It can be aligned evenly. Therefore, the short side and the center side can be bonded uniformly at the same timing. In addition, the outside is not melted and crushed by the hot press too much. Thereby, the conduction path of predetermined length in a resin layer can be hold | maintained, and it can prevent that a melt nonuniformity arises in a lamination direction. As a result, the above objects and effects can be sufficiently achieved.

In addition, in the coating part of the resin layer 18, resin which has melting | fusing point higher than the temperature (usually about 95 degreeC; see Example) of the apparatus (jig) 20 which heat-presses the power generating element 21 from up and down is Used. This is because the softening start has softened from a temperature lower than the melting point of the coating portion of the resin layer 18. This is because all of the resins (including copolymers and polymer alloys) used in the coating portion of the resin layer 18 are not the same (uniform) in molecular weight, molecular structure, resin shape, etc., but have a constant distribution. Therefore, the surface of the coating part of the resin layer softens sufficiently (heat-melts) at the temperature actually lower than melting | fusing point obtained by measuring methods, such as JIS. Therefore, since adhesiveness (adhesiveness) comes out at lower temperature, it can fully adhere | attach with an electrode or a separator. However, the temperature which starts to soften (temperature which becomes adhesive) is proportional to melting | fusing point of the coating part of the resin layer 18. FIG. Therefore, while keeping the shape of the separator by keeping the melting point of the coating portion of the resin layer 18 lower than the melting point of the separator, the surface of the coating portion of the resin layer 18 is softened to give adhesiveness, thereby sufficiently adhering the electrode-separator. You can. As a result, the above objects and effects can be achieved.

Melting | fusing point of the coating part of the said resin layer 18 and a separator can be measured by the following method.

Melting | fusing point is calculated | required from the endothermic peak at the time of heating up at 20 degree-C / min with a differential scanning calorimeter (DSC).

Specifically, it measures on the following conditions using the differential scanning calorimeter made from Seiko Electronics Corporation, for example.

Sample amount: about 5mg

Atmosphere gas: Nitrogen (flow rate 20 ml / min)

Temperature condition: After holding for 10 minutes at 230 degreeC, it temperature-falls to 30 degreeC at 10 degreeC / min, and then measures the endothermic behavior of fusion when heated up at the temperature increase rate of 10 degreeC / min.

Hereinafter, each structural requirement (structural member) of the laminated structure battery 10 of this embodiment is demonstrated. In addition, about each structural requirement (structural member) of the laminated structure battery 10, it is not limited only to the following form, A conventionally well-known form can also be employ | adopted similarly.

(1) The whole house

The current collector is made of a conductive material, and an active material layer is disposed on one side or both sides thereof. There is no restriction | limiting in particular in the material which comprises an electrical power collector, For example, the resin which has electroconductivity to which the conductive filler was added to a metal, a conductive polymer material, or a nonelectroconductive polymer material can be employ | adopted.

Examples of the metal include aluminum, nickel, iron, stainless steel, titanium and copper. In addition to these, a cladding material of nickel and aluminum, a cladding material of copper and aluminum, or a plating material of a combination of these metals can be preferably used.

Alternatively, the metal foil may be a foil in which aluminum is coated on the metal surface. Especially, aluminum, stainless steel, and copper are preferable from a viewpoint of electroconductivity and battery operation potential.

As a form of the electrical power collector using metal, you may use a metal vapor deposition layer, a metal plating layer, a conductive primer layer, and metal wiring other than metal foil. The metal deposition layer and the metal plating layer can form (arrange) an extremely thin metal deposition layer or a metal plating layer on one surface of the active material layer by vacuum deposition or various plating methods. Metal wiring can also form (arrange) an extremely thin metal wiring on one surface of the active material layer by vacuum deposition or various plating methods. In addition, the primer layer can be impregnated into the metal wiring to be attached by thermocompression bonding. In addition, when using a punching metal sheet or an expanded metal sheet as a metal wiring, an electrode slurry is apply | coated and dried on both surfaces of a punching metal sheet or an expanded metal sheet, and the metal wiring (current collector) inserted in the active material layer can be arrange | positioned. Can be. Even when metal foil is used, metal foil (current collector) can be arrange | positioned on the single side | surface of an active material layer by apply | coating and drying an electrode slurry on metal foil (one side or both sides). The conductive primer layer can be produced by mixing a resin with carbon (chain, fibrous) or metal filler (aluminum, copper, stainless steel, nickel powder, etc. used for current collector materials). Mixtures vary. It can form (arrangement) by apply | coating this to single side | surface of an active material layer, and drying.

The said electroconductive primer layer contains the electrical power collector resin layer. Preferably, the conductive primer layer is made of a current collecting resin layer having conductivity. In order for an electroconductive primer layer to have electroconductivity, as a specific aspect, 1) the aspect which the polymer material which comprises resin is a conductive polymer, and 2) the aspect in which the collector resin layer contains resin and a conductive filler (conductive material) are mentioned.

The conductive polymer is selected from materials that have conductivity and are not conductive to ions that can be used as charge transfer media. It is believed that these conductive polymers exhibit conductivity by the conjugated polyene system forming an energy band. As a representative example, a polyene-based conductive polymer that has been put into practical use in an electrolytic capacitor or the like can be used. Specifically, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylenevinylene, polyacrylonitrile, polyoxadiazole or mixtures thereof and the like are preferable. Polyaniline, polypyrrole, polythiophene, polyacetylene are more preferable from the viewpoint of electron conductivity and stable use in a battery.

The conductive filler (conductive material) used in the form of 2) above is selected from a material having conductivity. Preferably, from the viewpoint of suppressing ion permeation in the conductive current collecting resin layer, it is preferable to use a material having no conductivity with respect to ions that can be used as the charge transfer medium.

Although an aluminum material, a stainless steel (SUS) material, a carbon material, a silver material, a gold material, a copper material, a titanium material etc. are mentioned specifically, It is not limited to these. These electroconductive fillers may be used individually by 1 type, and may be used together 2 or more types. Moreover, these alloy materials may be used. Preferably a silver material, a gold material, an aluminum material, a stainless material, a carbon material, and more preferably a carbon material. These conductive fillers (conductive materials) may be those obtained by coating a conductive material (the conductive material) with a plating or the like around the particulate ceramic material or the resin material.

Examples of the carbon material include at least one member selected from the group consisting of acetylene black, balkan, black pearl, carbon nanofiber, ketjen black, carbon nanotube, carbon nanohorn, carbon nanoballoon, hard carbon and fullerene. Can be. These carbon materials have a very wide potential window, are stable in a wide range with respect to both the positive electrode potential and the negative electrode potential, and are excellent in conductivity. In addition, since the carbon material is very lightweight, the increase in mass is minimized. In addition, since the carbon material is often used as a conductive aid of an electrode, even if it contacts with these conductive aids, since it is the same material, contact resistance becomes very low. In the case where the carbon material is used as the conductive particles, the surface of the carbon may be hydrophobic to reduce the familiarity of the electrolyte and create a situation in which the electrolyte is difficult to infiltrate the pores of the current collector.

There is no restriction | limiting in particular in the shape of an electroconductive filler (conductive material), Well-known shapes, such as a particulate form, a powder state, a fibrous form, a plate form, a block form, cloth form, or a mesh form, can be selected suitably. For example, when it is desired to provide conductivity over a wide range of resins, it is preferable to use a particulate conductive material. On the other hand, when it is desired to further improve the conductivity in a specific direction in the resin, it is preferable to use a conductive material that has a certain directivity in shapes such as fibrous shapes.

Although the average particle diameter of an electroconductive filler is not specifically limited, It is preferable that it is about 0.01-10 micrometers. In addition, in this specification, "particle diameter" means the largest distance L among the distance between arbitrary two points on the outline of an electrically conductive filler. As a value of an "average particle diameter", the value computed as an average value of the particle diameter of the particle observed in several to several tens of visual fields using observation means, such as a scanning electron microscope (SEM) and a transmission electron microscope (TEM), We shall adopt. The particle diameter and the average particle diameter of the active material particles to be described later can also be similarly defined.

In the case where the current collecting resin layer contains a conductive filler, the resin forming the current collecting resin layer may include a non-conductive polymer material for binding the conductive filler in addition to the conductive filler. By using a polymer material having no conductivity as a constituent material of the current collecting resin layer, the binding property of the conductive filler can be improved, and the reliability of the battery can be improved. The polymer material is selected from a material capable of withstanding the applied positive electrode potential and negative electrode potential.

Examples of the nonconductive polymer material are preferably polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide PA), polyamideimide (PAI), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethylmethacrylate ), Polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), polyvinylidene chloride (PVDC), or mixtures thereof. These materials have a wide potential window and are stable to any of the positive electrode potential and the negative electrode potential. Also, since it is light in weight, high output density of the battery can be achieved.

The content of the conductive filler is not particularly limited. In particular, when the resin contains a conductive polymer material and can secure sufficient conductivity, the conductive filler does not necessarily need to be added. However, in the case where the resin is made of only the non-conductive polymer material, the addition of the conductive filler is essential to impart conductivity. Content of the electrically conductive filler at this time becomes like this. Preferably it is 5-90 mass% with respect to the total mass of a nonelectroconductive polymer material, More preferably, it is 30-85 mass%, More preferably, it is 50-80 mass%. By adding such an amount of the conductive filler to the resin, sufficient conductivity can be imparted to the non-conductive polymer material while suppressing increase in the mass of the resin.

The conductive primer layer may contain other additives in addition to the conductive filler and the resin, but is preferably made of the conductive filler and the resin.

Of the materials constituting the current collector, examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile and polyoxadiazole And the like. Such a conductive polymer material is advantageous in terms of facilitating the manufacturing process or lightening the current collector because it has sufficient conductivity without adding the conductive filler.

Examples of the non-conductive polymer material include polyethylene (PE; high density polyethylene (HDPE), low density polyethylene (LDPE)), polypropylene (PP), polyethylene terephthalate (PET), polyethernitrile (PEN), and polyimide (PI). ), Polyamideimide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethylacrylate (PMA), polymethyl Methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), polystyrene (PS), and the like. Such a non-conductive polymer material may have excellent anti-satellite or solvent resistance.

A conductive filler may be added to the conductive polymer material or the non-conductive polymer material as needed. In particular, when the resin serving as the base material of the current collector is made of only the non-conductive polymer, an electrically conductive filler is indispensable in order to impart conductivity to the resin. The conductive filler can be used without particular limitation as long as it is a conductive material. For example, metal, electroconductive carbon, etc. are mentioned as a material excellent in electroconductivity, electric potential resistance, or lithium ion barrier property. The metal is not particularly limited, but at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, Sb and K or an alloy containing these metals or It is preferable to include a metal oxide. In addition, the conductive carbon is not particularly limited, and includes at least one selected from the group consisting of acetylene black, balkan, black pearl, carbon nanofiber, ketjen black, carbon nanotube, carbon nanohorn, carbon nanoballoon and fullerene. It is desirable to. There is no restriction | limiting in particular if the addition amount of an electrically conductive filler is an amount which can provide sufficient electroconductivity to an electrical power collector, Generally, it is about 5-35 mass%.

The size of the current collector is determined depending on the intended use of the battery. For example, a current collector having a large area is used as long as it is used for a large battery requiring high energy density.

The thickness of the current collector is preferably 1 to 100 µm, more preferably 3 to 80 µm, still more preferably 5 to 40 µm. In the self-supporting electrode mentioned later, since thin film formation is possible, Preferably it is 1-18 micrometers, More preferably, it is 2-15 micrometers, More preferably, it is 3-13 micrometers. This can be produced without a conventional coating and drying step when the self-supporting electrode is manufactured. Therefore, when using the metal vapor deposition layer, the metal plating layer, the conductive primer layer, or the electrical power collector of a metal wiring which do not need to go through the conventional coating and drying process, it has the tensile strength required by the coating and drying process. no need. As the need arises, the thickness of the current collector can be made thinner, thereby increasing the degree of freedom in designing the current collector and contributing to the weight reduction of the electrode and the battery.

In the case of using a punching metal sheet or expanded metal sheet having a plurality of through holes as the current collector, as the shape of the through holes, square, rhombus, bone shape, hexagon, circle, square, shaping, cross, etc. may be mentioned. Can be. The so-called punching metal sheet or the like is formed by pressing a plurality of holes of such a predetermined shape, for example, in a zigzag arrangement or a parallel arrangement. In addition, what is called expanded metal sheet | seat etc. which extended | stretched the sheet | seat which inserted the zigzag-shaped perforation line, and formed many rhombic through-holes was formed.

When the current collector having the plurality of through holes is used in the current collector, the opening ratio of the through holes of the current collector is not particularly limited. However, the lower limit of the opening ratio of the current collector is preferably 10 area% or more, more preferably 30 area% or more, still more preferably 50 area% or more, still more preferably 70 area% or more, further preferably Is 90 area% or more. As described above, in the electrode of the present embodiment, a current collector having an aperture ratio of 90 area% or more can also be used. Moreover, as an upper limit, it is 99 area% or less, or 97 area% or less, for example. As described above, the laminated structure battery 10 including the electrode formed with the current collector having a significantly large aperture ratio can significantly reduce its weight, further increase its capacity, and increase its density. have.

In the case where the current collector having the plurality of through holes described above is used for the current collector, the hole diameter (opening diameter) of the through holes of the current collector is similarly not particularly limited. However, the lower limit of the opening diameter of the current collector is preferably 10 µm or more, more preferably 20 µm or more, still more preferably 50 µm or more, and particularly preferably 150 µm or more. The upper limit is, for example, about 300 μm or less, preferably about 200 μm or less. In addition, the opening diameter here is the diameter of the circumscribed circle of a through-hole (= opening part). The diameter of the circumscribed circle is obtained by observing the surface of the current collector with a laser microscope, a tool microscope or the like, fitting a circumscribed circle to the opening, and averaging it.

(2) An electrode (positive electrode and negative electrode) and an electrode active material layer

The positive electrode and the negative electrode have a function of generating electrical energy by sorghum of lithium ions. The positive electrode essentially includes a positive electrode active material, and the negative electrode active essentially includes a negative electrode active material.

In the case of a laminated structure battery, these electrode structures are structures in which an active material layer containing an active material is formed on the surface of the current collector as in the embodiment of FIG. 1. On the other hand, in the case of a bipolar secondary battery, a positive electrode active material layer containing a positive electrode active material is formed on one surface of a current collector, and a negative electrode active material layer containing a negative electrode active material is formed on another surface thereof. It has a structure made up of. That is, it has a form in which a positive electrode (positive electrode active material layer) and a negative electrode (negative electrode active material layer) are integrated through a current collector. In addition to the active material, the active material layer may contain additives such as an electrolyte salt (lithium salt) and an ion conductive polymer as the conductive aid, binder, and electrolyte as necessary.

(2a) Positive electrode active material

As a positive electrode active material, a conventionally well-known thing can be used.

As the positive electrode active material, for example, LiMn ₂ O ₄ , LiCoO ₂ , LiNiO ₂ , Li (Ni, Co, Mn) O ₂ , Li ₂ MnO ₃ , Li ₂ MnO ₃ -LiMO _{2 type} (M = Co, Ni, etc.) And a lithium-transition metal composite oxide, a lithium-transition metal phosphate compound, a lithium-transition metal sulfate compound, and the like, in which a solid solution and a part of these transition metals are substituted by other elements. In some cases, two or more kinds of positive electrode active materials may be used in combination. Preferably, from the viewpoints of capacity and output characteristics, a lithium-transition metal composite oxide is used as the positive electrode active material. It goes without saying that other positive electrode active materials may be used. In addition, high-density positive electrode active materials such as LiNiO ₂ , Li (Ni, Co, Mn) O ₂ , and Li ₂ MnO ₃ tend to increase the capacity of the battery, and when used in a vehicle-mounted battery, the travel distance in one charge It is also advantageous in that it can be extended.

The average particle diameter of the positive electrode active material is not particularly limited, but is preferably 1 to 25 占 퐉 in view of high output.

Although the quantity in particular of a positive electrode active material is not restrict | limited, Preferably it is 50 to 99 mass% with respect to the total amount of the raw material for positive electrode active material layer formation, More preferably, it is 70 to 97%, More preferably, it is 80 to 96% of range.

(2b) Negative electrode active material

A negative electrode active material has a composition which can discharge lithium ion at the time of discharge, and can occlude lithium ion at the time of charge. The negative electrode active material is not particularly limited as long as it can absorb and release lithium, but examples of the negative electrode active material include metals such as Si and Sn, or TiO, Ti ₂ O ₃ , TiO ₂ , or SiO ₂ , SiO, SnO. _2, and a metal _{oxide, Li 4/3 Ti 5/} 3 O 4 or Li ₇ composite oxide of lithium and transition metals and the like MnN, Li-Pb alloy, Li-Al alloy, Li, or natural graphite, artificial graphite Carbon materials, such as carbon black, activated carbon, carbon fiber, coke, soft carbon, or hard carbon, etc. are mentioned preferably. Among these, by using an element alloyed with lithium, it becomes possible to obtain a battery of high capacity and excellent output characteristics having a higher energy density than conventional carbon-based materials. The said negative electrode active material may be used independently or may be used in the form of 2 or more types of mixtures. Examples of the element alloyed with lithium include, but are not limited to, Si, Ge, Sn, Pb, Al, In, Zn, H, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Au, Cd, Hg, Ga, Tl, C, N, Sb, Bi, O, S, Se, Te, Cl and the like.

Among the active materials, it is preferable to include a carbon material and / or at least one or more elements selected from the group consisting of Si, Ge, Sn, Pb, Al, In, and Zn. It is more preferable to include. Among the carbon materials, graphite having a discharge potential lower than that of lithium is more preferably used.

When using the said negative electrode active material as a negative electrode, the negative electrode active material layer containing a negative electrode active material may be shape | molded in plate shape, and it may be a negative electrode as it is, or may be a negative electrode by forming the negative electrode active material layer containing the said negative electrode active material particle on the surface of an electrical power collector. . The average particle diameter of the negative electrode active material particles in the latter aspect is not particularly limited, but is preferably 1 to 100 µm from the viewpoint of high capacity, reactivity, and cycle durability of the negative electrode active material, and from the viewpoint of high output, Preferably it is 1-25 micrometers. If it is this range, the secondary battery can suppress the increase of the internal resistance of the battery at the time of charge / discharge under high output conditions, and can take out sufficient electric current. In addition, when the negative electrode active material is a secondary particle, it can be said that the average particle diameter of the primary particle which comprises the said secondary particle is preferable in the range of 10 nm-1 micrometer, However, in this embodiment, it is necessarily limited to the said range. It is not. However, although it depends also on a manufacturing method, it cannot be overemphasized that the negative electrode active material does not need to be secondary particle | grains by aggregation, agglomeration, etc. The particle diameter of such a negative electrode active material and the particle diameter of primary particles can use the median diameter obtained using the laser diffraction method. In addition, the shape of the negative electrode active material particles is different in the shape that can be taken by its type, manufacturing method, or the like, and examples thereof include spherical shape (powder state), plate shape, needle shape, columnar shape, and angular shape. It is not limited, and any shape can use it without a problem. Preferably, it is preferable to appropriately select an optimal shape capable of improving battery characteristics such as charge and discharge characteristics.

The amount of the negative electrode active material is not particularly limited, but is preferably in the range of 50 to 99% by mass, more preferably 70 to 97%, still more preferably 80 to 96% with respect to the total amount of the raw material for forming the negative electrode active material layer.

(2b) challenge aids

A conductive support agent means the additive mix | blended in order to improve the electroconductivity of an active material layer. Examples of the conductive auxiliary agent include carbon powder such as acetylene black, carbon black, Ketjen black and graphite, various carbon fibers such as vapor grown carbon fiber (VGCF; registered trademark), and expanded graphite. However, needless to say, the conductive assistant is not limited to these. When an active material layer contains a conductive support agent, the electronic network in an inside of an active material layer can be formed effectively, and can contribute to the improvement of the output characteristic of a battery.

Content of the conductive support agent mix | blended with a positive electrode active material layer is 1 mass% or more with respect to the total amount of the raw material for positive electrode active material layer formation, More preferably, it is 3 mass% or more, More preferably, it is the range of 5 mass% or more. Moreover, content of the conductive support agent mixed in a positive electrode active material layer is 15 mass% or less with respect to the total amount of the raw material for positive electrode active material layer formation, More preferably, it is 10 mass% or less, More preferably, it is the range of 7 mass% or less. The following effects are exhibited by defining the compounding ratio (content) of the electrically conductive adjuvant in the positive electrode active material layer which is low in electronic conductivity of an active material itself and which can reduce electrode resistance by the quantity of an electrically conductive adjuvant. That is, the effect of the present embodiment can be expressed without inhibiting the electrode reaction. In addition, the electronic conductivity can be sufficiently secured, a decrease in the energy density due to the decrease in the electrode density can be suppressed, and further, the energy density can be improved by the improvement in the electrode density.

As content of the conductive support agent mix | blended with a negative electrode active material layer, since it changes with a negative electrode active material, it cannot be uniquely prescribed. That is, when using carbon materials and metal materials, such as graphite (graphite), soft carbon, and hard carbon which have the outstanding electron conductivity excellent in the negative electrode active material itself, containing of the conductive support agent to a negative electrode active material layer does not need in particular. Even if it contains a conductive support agent, it is sufficient in the range of 0.1-1 mass% at most with respect to the total amount of the electrode structural material of a negative electrode side. On the other hand, similar to the positive electrode active material, the electronic conductivity is low and the electrode resistance can be reduced by the amount of the conductive assistant. In the case of using a negative electrode active material such as a lithium alloy negative electrode material or a lithium-transition metal composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ), the content is about the same as the content of the conductive assistant mixed in the positive electrode active material layer. It is desirable to. That is, the content of the conductive assistant mixed in the negative electrode active material layer is also preferably 1 to 10% by mass, more preferably 2 to 8% by mass, particularly preferably 3 to 7 with respect to the total amount of the electrode constituent material on the negative electrode side. It is preferable to make mass% into a range.

(2c) Binder (binder)

A binder is added in order to bind | conclude the structural members in an active material layer, or to bind an active material layer and an electrical power collector, and to maintain an electrode structure. As a binder, it is an insulating material which can achieve the said objective, It should just be a material which does not produce a side reaction (redox reaction) at the time of charge and discharge, Although it does not specifically limit, For example, the following materials are mentioned. Polyethylene, polypropylene, polyethylene terephthalate (PET), polyethernitrile, polyacrylonitrile, polyimide, polyamide, cellulose, carboxymethyl cellulose (CMC), ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene butadiene Rubber (SBR), isoprene rubber, butadiene rubber, ethylene propylene rubber, ethylene propylene diene copolymer, styrene butadiene styrene block copolymer and its hydrogenated substance, styrene isoprene styrene block copolymer and its hydrogenated substance Thermoplastic polymer, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), tetrafluoroethylene hexafluoropropylene copolymer (FEP), tetrafluoroethylene perfluoro alkyl vinyl ether copolymer ( PFA), ethylene tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), Fluorine resins such as methylene chlorotrifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF), vinylidene fluoride-hexafluoropropylene fluorine rubber (VDF-HFP fluorine rubber), vinylidene fluoride- Hexafluoropropylene-tetrafluoroethylene fluorine rubber (VDF-HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoro propylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-penta Fluoropropylene-tetrafluoroethylene-based fluororubbers (VDF-PFP-TFE-based fluororubbers), vinylidene fluoride-perfluoromethylvinylether-tetrafluoroethylene-based fluororubbers (VDF-PFMVE-TFE-based fluororubbers) And vinylidene fluoride-based fluorine rubbers such as vinylidene fluoride-chlorotrifluoroethylene-based fluorine rubber (VDF-CTFE-based fluorine rubber) and epoxy resins. Among these, polyvinylidene fluoride, polyimide, styrene-butadiene rubber, carboxymethylcellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile and polyamide are more preferable. These suitable binders are excellent in heat resistance, have a wide potential window, are stable at both the positive electrode potential and the negative electrode potential, and can be used for the active material layer. These binders may be used alone or in combination of two or more. However, needless to say, the binder is not limited to these.

Although the quantity of a binder will not be specifically limited if it is an quantity which can bind an active material etc., Preferably it is 0.5-15 mass% with respect to the total amount of the raw material for electrode active material layer formation, More preferably, it is 1-10 mass%.

(2d) Electrolyte salt (lithium salt)

Examples of the electrolyte salt (lithium salt) include Li (C ₂ F ₅ SO ₂ ) ₂ N, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , and the like. Further, an electrolyte salt (lithium salt) used in an electrolyte layer described later can be suitably used.

(2e) ion conductive polymers

Examples of the ion conductive polymer include polymers based on polyethylene oxide (PEO) and polypropylene oxide (PPO). Furthermore, the electrolyte salt (lithium salt) used for the electrolyte layer mentioned later can be used suitably.

(2f) Porous Skeletal Body Used for Freestanding Electrodes

As a porous skeleton, a nonwoven fabric, a woven fabric, a metal foam (or a metal porous body), carbon paper, etc. are preferable. Among these, the nonwoven fabric used for a porous skeleton is formed by overlapping fibers in different directions. Resin materials are used for the nonwoven fabric, and fibers such as polypropylene, polyethylene, polyethylene terephthalate, cellulose, nylon, and EVA resin (ethylene-vinyl acetate copolymer resin) can be applied. Moreover, as a form other than a nonwoven fabric as a porous skeleton body, the resin woven fabric (regular resin porous body), a metal foam, or a metal porous body, carbon paper, etc. are mentioned. Here, as resin used for the woven fabric made of resin, although polypropylene, polyethylene, polyethylene terephthalate, EVA resin, etc. can be illustrated, it is not limited to these at all. As a metal foam or a metal porous body, Preferably, at least 1 sort (s) of metal foam, a metal porous body, etc. of Cu, Ni, Al, Ti, etc. can be illustrated, but it is not limited to these at all. Preferably, it is a nonwoven fabric made of at least one metal porous body of Cu or Al, carbon paper, polypropylene, polyethylene or EVA resin.

The ratio of the porous skeleton of the skeleton occupying the active material layer is not less than 2% by volume, preferably not less than 7% by volume. On the other hand, the ratio of the porous skeleton of the skeleton occupying the active material layer is 28 vol% or less, preferably 12 vol% or less. When the proportion of the porous skeleton occupying the active material layer is within the above range, the electrode reaction is not hindered.

As a porosity (porosity) of a porous skeleton, Preferably it is 70%-98%, More preferably, it is 90-95%. Within the above range, the effect of the present invention can be effectively obtained.

As a pore diameter of a porous skeleton, about 50-100 micrometers which can fully fill the active material currently used on the market is preferable. Within the above range, the effect of the present invention can be effectively obtained. That is, if the pore diameter of the porous skeleton is 100 μm or less, the effect of the present embodiment is effectively obtained. If the pore diameter is 50 μm or more, the particle size of the active material to be used is not restricted, and an appropriate active material is appropriately selected according to the intended use. Excellent in terms of choice.

The thickness of the porous skeleton may be smaller than the thickness of the active material layer, and is usually about 1 to 120 mu m, preferably about 1 to 20 mu m.

Although there is no restriction | limiting in particular also about the thickness of each active material layer, From a viewpoint of suppressing electronic resistance, it is preferable that the thickness (one side) of each active material layer is about 1-120 micrometers.

About the hollow ratio of each active material layer, the hollow ratio of each active material layer is about 10 to 40% from a viewpoint of improving the electroconductivity (diffusion property) of Li ion by impregnation and holding | maintenance of electrolyte solution, or suppressing an electronic resistance. It is preferable.

(3) The electrolyte layer

The electrolyte layer of this embodiment consists of an electrolyte and the separator which impregnates or hold | maintains the said electrolyte in a hole. The electrolyte layer having a separator functions as a spatial partition (spacer) between the positive electrode and the negative electrode. In addition to this, it also has a function of holding an electrolyte which is a moving medium of lithium ions between the stationary electrodes during charging and discharging. In the present embodiment, as described above, the resin layer 18 is used to bond the separator and the electrode to prevent short circuit due to thermal contraction of the separator.

There is no restriction | limiting in particular in the electrolyte which comprises an electrolyte layer, A polymer electrolyte, such as a liquid electrolyte and a polymer gel electrolyte and a polymer solid electrolyte, can be used suitably.

(3a) Liquid electrolyte

The liquid electrolyte is obtained by dissolving a lithium salt as a supporting salt in a solvent. As a solvent, for example, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propionate (MP), methyl acetate ( MA), methyl formate (MF), 4-methyldioxolane (4MeDOL), dioxolane (DOL), 2-methyltetrahydrofuran (2MeTHF), tetrahydrofuran (THF), dimethoxyethane (DME), ethylenecarb Carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GBL), and the like. These solvents may be used singly or as a mixture of two or more kinds. The supporting salt (lithium salt) is not particularly limited, but LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiSbF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ , LiI, LiBr, LiCl, LiAlCl , Inorganic acid anion salts such as LiHF ₂ , LiSCN, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiBOB (lithium bisoxido borate), LiBETI (lithium bis (fluoroethylene sulfonylimido); And organic acid anion salts such as (C ₂ F ₅ SO ₂ ) ₂ N). These electrolyte salts may be used alone or in the form of a mixture of two or more thereof.

On the other hand, the polymer electrolyte is classified into a gel electrolyte containing an electrolyte solution and a polymer solid electrolyte containing no electrolyte solution.

(3b) Gel electrolyte

The gel electrolyte has a configuration in which the liquid electrolyte is injected into a matrix polymer having lithium ion conductivity. Examples of the matrix polymer having lithium ion conductivity include polymer (PEO) having polyethylene oxide in the main chain or side chain, polymer (PPO) having polypropylene oxide in the main chain or side chain, polyethylene glycol (PEG), polyacrylonitrile (PAN), polymethacrylic acid ester, polyvinylidene fluoride (PVdF), a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN) ) (PMA), and poly (methyl methacrylate) (PMMA). Moreover, mixtures, modified bodies, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers and the like of the above polymers can also be used. Of these, PEO, PPO and their copolymers, PVdF and PVdF-HFP are preferably used. Electrolyte salts such as lithium salts can dissolve well in such a matrix polymer.

(3c) Polymer solid electrolyte

The polymer solid electrolyte has a structure in which a supporting salt (lithium salt) is dissolved in the matrix polymer and does not contain an organic solvent. Therefore, when the electrolyte layer is composed of a polymer solid electrolyte, there is no worry of leakage from the battery, and the reliability of the battery can be improved.

The matrix polymer of the polymer gel electrolyte or the polymer solid electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, a polymerization process such as thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization or the like is performed on a polymerizable polymer (for example, PEO or PPO) for polymer electrolyte formation using a suitable polymerization initiator. Just do it. The electrolyte may be included in the active material layer of the electrode.

(3d) Separator

There is no restriction | limiting in particular as a separator, A conventionally well-known thing can be used suitably. For example, a separator or a nonwoven fabric separator of a porous sheet made of a polymer or a fiber absorbing and retaining the electrolyte may be mentioned.

As the separator of the porous sheet made of the above polymer or fiber, for example, microporous (microporous membrane) can be used. Specific examples of the porous sheet made of the polymer or the fiber include polyolefins such as polyethylene (PE) and polypropylene (PP); (For example, a laminate having a three-layer structure of PP / PE / PP or the like), a polyimide, an aramid, and a hydrocarbon-based material such as polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) And a microporous (microporous membrane) separator made of resin, glass fiber or the like.

As thickness of the said microporous (microporous membrane) separator differs according to a use, it cannot be prescribed | regulated uniquely. When an example is shown, it is preferable that it is 4-60 micrometers in single layer or multilayer in the use of motor drive secondary batteries, such as an electric vehicle EV, a hybrid electric vehicle HEV, and a fuel cell vehicle FCV. It is preferable that the micropore diameter of the said microporous (microporous membrane) separator is at most 1 micrometer or less (usually a pore diameter of several tens of nm), and the porosity (porosity) is 20 to 80%.

Examples of the nonwoven fabric separator include cotton, rayon, acetate, nylon, polyester; Polyolefins such as PP and PE; Polyimide, and aramid, which are conventionally known, may be used alone or in combination. In addition, the bulk density of a nonwoven fabric should just be sufficient battery characteristics obtained by the impregnated polymer gel electrolyte, and it does not need to restrict | limit in particular.

It is preferable that the porosity (porosity) of the said nonwoven fabric separator is 45 to 90%. In addition, the thickness of a nonwoven fabric separator should just be the same as an electrolyte layer, Preferably it is 5-200 micrometers, Especially preferably, it is 10-100 micrometers. When the thickness is less than 5 mu m, the retention of the electrolyte deteriorates, and when the thickness exceeds 200 mu m, the resistance increases.

(4) resin layer

The resin layer should just be provided in order to adhere | attach an electrode (positive electrode or negative electrode) with either of a separator, and to prevent the short circuit by the thermal contraction of a separator.

As a material used for the resin layer of this embodiment, it is an insulating material which can achieve the said objective, It should just be a material which does not produce a side reaction (redox reaction) at the time of charge and charge, and it is although it does not specifically limit, For example, A material is mentioned. Olefin-based resins such as polyethylene (PE) and polypropylene (PP), polyethylene terephthalate (PET), polyethernitrile, polyacrylonitrile, polyimide, polyamide, cellulose, carboxymethyl cellulose (CMC), ethylene-acetic acid Vinyl copolymer, polyvinyl chloride, styrene butadiene rubber (SBR), isoprene rubber, butadiene rubber, ethylene propylene rubber, ethylene propylene diene copolymer, styrene butadiene styrene block copolymer and its hydrogenated substance, styrene and Thermoplastic polymers such as isoprene styrene block copolymers and hydrogenated products thereof, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polytetrafluoroethylene (PTFE), tetrafluoro Ethylene hexafluoropropylene copolymer (FEP), tetrafluoroethylene perfluoro alkyl vinyl ether copolymer (PFA), ethylene Fluororesins such as trifluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), vinylidene fluoride-hexa Fluoropropylene-based fluorine rubber (VDF-HFP-based fluorine rubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluorine rubber (VDF-HFP-TFE-based fluorine rubber), vinylidene fluoride-pentafluor Low propylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-pentafluoro propylene-tetrafluoroethylene fluorine rubber (VDF-PFP-TFE type fluorine rubber), vinylidene fluoride-perfluoro Vinylidene flu such as methyl vinyl ether tetrafluoroethylene fluorine rubber (VDF-PFMVE-TFE fluorine rubber), vinylidene fluoride-chlorotrifluoroethylene fluorine rubber (VDF-CTFE fluorine rubber) It may include fluoride-based rubber, a fluorine-containing epoxy resin, (meth) acrylic resin, an aramid or the like. Among these, polyvinylidene fluoride, polyimide, styrene-butadiene rubber, carboxymethylcellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile and polyamide are more preferable. The material used for these suitable resin layers is excellent in heat resistance, the potential window is very wide, and is stable to both a positive electrode potential and a negative electrode potential, and can be used for a resin layer. The material used for these resin layers may be used independently and may use 2 or more types together. However, it goes without saying that the material used for the resin layer is not limited to these. Among them, for example, polyvinylidene fluoride (PVdF), (meth) acrylic resin, olefin resin, and the like are strong to any potential on the positive electrode side and the negative electrode side, and therefore can be applied to either. Further, SBR or the like is preferably used on the negative electrode side since it is strong against the negative electrode potential. Further, PTFE or the like is preferably used on the positive electrode side since it is strong to the positive electrode potential.

In this embodiment, it is preferable that the coating part of at least 1 resin layer in a lamination direction, Preferably the coating part of all the resin layers 18 contains polyvinylidene fluoride (PVDF). By forming the coating part of the resin layer of each unit cell from PVDF or a material containing PVDF, the adhesive temperature (temperature at which the surface of the coating part of the resin layer softens to have initial adhesiveness; melting point (softening point temperature)) is defined by the separator deformation temperature region; The temperature can be set below the melting point (softening point temperature). Therefore, since battery reaction is not inhibited as much as possible, it is more effective in an output characteristic. In addition, since the amount of modification from the softening start temperature is large, the material containing PVDF or PVDF can be directly adhered, so that the hot press time can be shortened or the hot press temperature can be set low.

As a material containing PVDF, a homopolymer of PVDF, a substituent (for example, a carboxyl group) is introduced into a part of the PVDF (for example, a side chain of a repeating unit, etc.), and the PVDF is different from one or more polymers. Random, block, alternating, graft copolymers (binary copolymers, tertiary copolymers, quaternary copolymers, etc.), polymer alloys containing PVDF and one or more other (co) polymers; Above all, it is incorporated a carboxyl group by a PVDF (e.g., the structure having a carboxyl group in the side chain portion; - (CH (COOH) -CF 2) n -, or _{- (CH 2 -CF (COOH)} ) n - Or-(CH ₂ -CF _2- ) _n- (CH (COOH) -CF ₂ ) _m- , or-(CH ₂ -CF _2- ) _n- (CH ₂ -CF (COOH)) _m -and the like) This is preferred. Melting | fusing point of a coating part can be reduced (controlled) about 1-10 degreeC by mixing a carboxyl group in PVDF, and it is excellent in the point which can make desired melting | fusing point material simple by adjusting the amount of mixing of carboxyl group.

In addition, in this embodiment, the form in which the coating part of the said resin layer 18 contains styrene butadiene rubber (SBR) is also one of the suitable forms. In the case of SBR, since it is a copolymer of styrene and butadiene, since melting | fusing point of a coating part can be raised about 1 to 10 degreeC by increasing the ratio of styrene, it is excellent at the point which can make desired melting point material simple.

In this embodiment, the said resin layer 18 has a coating part and an uncoated part. That is, a coating part exists in stripe shape or a dot shape on the surface of a separator and an electrode. The thickness of the coating part of the resin layer 18 can suppress that the diffusion distance of Li ions becomes long as thin as possible within the range which can achieve the objective of this embodiment, and also to reduce the weight of a battery It is preferable at the point which contributes. In particular, in the present embodiment, the desired purpose is achieved by changing the area of a single coating part without changing the thickness of the resin layer (= without changing the thickness of the resin layer of each unit cell layer) on the short side and the center side in the stacking direction. The effect can be realized. Thereby, it is not necessary to change a production facility (especially thickness adjustment) etc., and is excellent in production efficiency. From such a viewpoint, the thickness of the coating part of the resin layer 18 depends on the form (stripe shape or dot shape) of the coating part, but is in the range of 0.1 to 5 mu m, preferably 1 to 2 mu m. If the thickness of the coating part of a resin layer is 0.1 micrometer or more, since manufacture can be made easy, and the thickness of the coating part of a resin layer is 5 micrometers or less, it is preferable, since there is little possibility that it may adversely affect the load characteristic of a battery.

Since the coating part of a resin layer may not be easily peeled off, the thickness of the coating part of a resin layer can be measured from a cross-sectional image of a SEM (scanning electron microscope) by disassembling a battery, making it cross-sectional.

What is necessary is just to determine the area ratio of an uncoated part with respect to the whole in-plane of a resin layer (electrode or separator surface) in consideration of adhesiveness and battery performance. Although it depends also on the porosity (porosity) of a separator, and the form (stripe shape or dot shape) of a separator specifically, the area ratio of an uncoated part is 60 to 99%, Preferably it is 70 to 99%. In other words, the area ratio of the coating part with respect to the whole surface inside of a resin layer is 1 to 40%, Preferably it is the range of 1 to 30%. By carrying out the area ratio of the uncoated part with respect to the whole surface inside of a resin layer in the said range, it is excellent in the point which does not prevent the diffusion of Li ion. In addition, the area ratio of the uncoated part with respect to the whole in-plane of the resin layer shown above is an example in the case where the porosity (porosity) of a separator is about 45 to 55%. When the porosity (hollow rate) of a separator increases or decreases, what is necessary is just to increase and decrease the area ratio of the uncoated part with respect to the whole surface inside of a resin layer in proportion to this. In this way, the ratio of the area of the uncoated portion to the entire in-plane of the resin layer is slightly higher than the porosity (porosity) of the separator so that the diffusion of Li ions is not inhibited due to the presence of the coating portion formed on the electrode surface. To do that. Especially in this embodiment, the area of the single coating part which comprises the coating part of the resin layer of the short side of a laminated structure battery is made large, and the area is reduced as it goes inside a lamination direction. By such a configuration, the melt rate of each resin layer can be uniformly aligned on the short side where the hot press temperature is high and the time is long, and the hot side where the hot press temperature is low and the time is short, and the desired purpose and effect can be realized. It is.

It is preferable that the porosity in the coating part of a resin layer is smaller, It is especially preferable that there is no pore, Specifically, 10% or less is preferable, Especially preferably, it is 0%. This is because the uncoated portion having a large area ratio effectively functions as a new electrolyte solution (electrolyte) holding portion.

The area ratio of the coated portion (or uncoated portion) present on the separator and the electrode surface is taken apart by dismantling the battery, and cross sectioning to map the coated portion (stripe-shaped or dot-shaped coated portion) from the SEM cross-sectional image. It can calculate by counting (measurement).

The porosity present in the coating portion of the resin layer can be measured by first disassembling the battery, taking out each single coating portion of each resin layer, washing away the electrolyte, drying, and using a mercury intrusion method or the like. . However, when the coating part of a resin layer cannot be peeled off easily, etc., a battery is disassembled, it is made to cross-sectionally, and the spatial part of the coating part of a resin layer is counted by mapping from the cross-sectional image of SEM (scanning electron microscope) (measurement | measurement). )You may.

As a form of a resin layer, what is necessary is just to have a coating part and an uncoated part so that the said objective may be achieved, and it is not specifically limited. The coating portions may be present at intervals such that a coating portion made of a resin material and an uncoated portion where the resin material does not exist are formed on the separator and the electrode surface. It is preferable that a coating part is arrange | positioned so that uniformity may be maintained on the surface of a separator and an electrode. Since the non-coated portion functions effectively as a liquid retaining space, the coating part may have a small amount of liquid retaining space (10% or less) (porous), but a non-coating portion (porosity 0%) having no liquid retaining space is present. desirable. In particular, when the coating part is provided in a dot shape (= when the ratio of the coating part is very small, for example, about 2% in Examples; see Table 1), the coating part is nonporous (0% porosity) where no liquid-retaining space exists. It is good to make).

FIG. 3A is a plan view showing a state in which a stripe coating part is provided on an electrode surface. 3 (B) and 3 (C) are plan views illustrating a state in which dot coating portions are provided on the electrode surface.

Specifically, the form as shown below is mentioned. (a) As shown in Fig. 3A, an uncoated portion is formed on the separator and the electrode surface 31 between the stripe coating portion 33a and the stripe coating portion 33a as a resin layer. The coating part 33a may exist at intervals so that the 35 may be formed. (b) As shown in FIGS. 3B and 3C, the separator and the electrode surface 31 between the dot-shaped coating portion 33b and the dot-shaped coating portion 33b as a resin layer. The coating part 33b may be interspersed and existed so that the uncoated part 35 may be formed in it. As a specific example of (b), the following forms are mentioned. (b1) Dot-shaped coating portions 33b are formed at four corners of the separator and the electrode surface 31. And coating part 33b may exist at intervals so that uncoated part 35 may be formed in separator and electrode surface 31 other than these four corner dots (coating part 33b) (FIG. B)). (b2) The dot-shaped coating part 33b is interspersed on the separator and the electrode surface 31 so as to maintain uniformity. And even if the coating part 33b exists at intervals so that the uncoated part 35 may be formed in the separator and electrode surface 31 between these dots (coating part 33b) and the dot (coating part 33b). do. For example, the dot-shaped coating part 33b of 12 points in total, 3 points x 4 points, is interspersed on the separator and the electrode surface 31 at equal intervals. And coating part 33b may exist at intervals so that uncoated part 35 may be formed in separator and electrode surface 31 other than these 12 dots (coating part 33b) (FIG.3 ( C)). However, the present invention is not limited to these forms, and the above-described objects such as lattice shape, rhombus lattice shape, rectangle, continuous or discontinuous ring or ellipse, polygonal shape, wave shape, semi-circle shape, irregular shape, etc. Any other form may be used as long as it can be achieved.

In addition, in this embodiment, it is preferable that melting | fusing point (or softening point) of the coating part of the resin layer 18 is lower than melting | fusing point (or softening point) of a separator. This is because the electrode-separator can be sufficiently bonded by softening the surface of the coating portion of the resin layer to give adhesiveness while maintaining the shape of the separator. Specifically, the melting point (or softening point) of the coating portion of the resin layer is preferably 5 to 10 ° C lower than the melting point (or softening point) of the separator. In addition, it is preferable to use the same thing for the separator of each unit cell of a lamination direction from a viewpoint of a production efficiency or a part management.

Here, the softening point temperature of the coating part of a resin layer and the softening point temperature of a separator can be measured as JISK7206 as both the Vicat softening temperature (Vicat softening temperature, Vicat Softening Temperature, VST). Explaining the outline of JISK7206, a test piece having a specified dimension is provided in a heating bath, and the temperature of the bath is raised while pressing the end face of a constant cross-sectional area (1 mm 2 in JIS K7206) in the center. The temperature at which the end face is fed into the test piece to a certain depth is the vicat softening temperature (unit: ° C). In addition, the measuring method of the melting point of the coating part of the resin layer 18, and the melting point of a separator is as having already mentioned above.

Formation of the resin layer, as shown in the Examples, is applied to the surface of the separator in advance, a resin slurry obtained by dissolving a resin material for forming the coating portion of the resin layer in a suitable solvent in a desired thickness and shape (stripe shape, dot shape). To dry. Thereby, a separator and a resin layer can be integrated (it is called a resin separator). In addition, when providing a resin layer in any one of the stationary electrodes, the effect of this embodiment is the same in any case. However, when the electrode sizes are different, the ones disposed on the larger electrode side (usually, the negative electrode side) are opposed to each other until the separator having the same size as the larger electrode heat shrinks and becomes smaller than the smaller electrode. It can be said that it is advantageous because the electrodes do not contact each other. This resin separator is sandwiched between the positive electrode and the negative electrode in the same manner as a normal separator to form the power generating element 21. Then, by hot pressing from the up-down direction of the power generating element 21 to the hot press apparatus (refer FIG. 2, 5) 20, the surface part of the coating part of the resin layer 18 of a resin separator is softened and adhesiveness is given out. It also adheres to the electrode. Thereby, the resin layer 18 formed by bonding between electrode and separator can be formed. Moreover, you may apply | coat a resin slurry to the electrode (positive electrode or negative electrode) side previously, and may produce the resin electrode (integrating an electrode and a resin layer). Thereafter, the power generation element 21 is similarly formed and hot-pressed to form the resin layer 18 formed by adhering the electrode-separator.

In this embodiment, the resin layer 18 has a coating part and an uncoated part. Further, the area of the single coating portion constituting the coating portion (when the coating portion is composed of a plurality of single coating portions, the average value of the areas of each single coating portion) is the center side <single side in the stacking direction. It is characterized by. Although it depends also on the lamination | stacking number of the single cell of a battery, and the magnitude | size of an electrode specifically, what is necessary is just the area (average value) of the single coating part of the resin layer of the single side of a lamination direction larger than the area (average value) of the single coating part of the resin layer of a center part. . Preferably, the area (average value) of the single coating portion of the resin layer on the single side in the stacking direction is preferably 1.1 to 4.0 times larger than the area (average value) of the single coating portion of the resin layer on the central portion, and more preferably 1.2 to 3.0. It is desirable to be twice as large. If the area of the single coating portion of the resin layer on the single side in the stacking direction is 1.1 times or more, preferably 1.2 times or more larger than the area of the single coating portion of the resin layer on the central portion, depending on the number of laminations, The resin layer can also be sufficiently bonded. Thereby, it can prevent that melt nonuniformity arises in a lamination direction. As a result, the above objects and effects can be sufficiently achieved. On the other hand, if the area of the single coating part of the resin layer on the single side in the stacking direction is 4.0 times or less, preferably 3.0 times or less than the area of the single coating part of the resin layer on the central portion, the melt rate of each resin layer is increased. It can be aligned evenly. Therefore, the short side and the center side can be bonded uniformly at the same timing. In addition, the outside is not melted and crushed by the hot press too much. Thereby, the conduction path of predetermined length in a resin layer can be hold | maintained, and it can prevent that a melt nonuniformity arises in a lamination direction. As a result, the above objects and effects can be sufficiently achieved.

In order to satisfy such a requirement, although the following structures (means) are mentioned, it is not necessarily limited to these structures (methods).

As said structure (means), the resin layer has a coating part and an uncoated part, The weight of the single coating part which comprises a coating part is set to the center side <end side in a lamination direction. In addition, the weight of a single coating part is taken as the average value of the weight of a single coating part, respectively, when a coating part consists of several single coating part. In other words, the resin layer is a dot or stripe-shaped coating portion and an uncoated portion, and the resin layer on the single side of the laminated structure battery increases the weight of the single coating portion, and the resin layer on the center side increases the weight of the single coating portion (dot Weight or the weight of the stripe). By setting it as such a structure, the resin layer 18 which increased the quantity of adhesive resin material (resin layer forming material) was used for the single side of the laminated structure battery 10, and the quantity of adhesive resin material was reduced along the lamination direction inner side. By using the resin layer 18, melt nonuniformity can be prevented in a lamination direction. That is, the weight (average value) of the single coating portion can be reduced as it faces the stacking direction center side of the stacked structure battery 10, the melt rates of the respective resin layers can be aligned uniformly, and the melt unevenness in the stacking direction can be reduced. It can prevent. As a result, the reaction distribution nonuniformity for every unit cell layer (monocell) can be prevented, and the durability of the whole laminated structure battery can be improved. In addition, by setting it as this structure, when hot-pressing the power generating element 21 with the apparatus 20 which heat-presses from top to bottom, as shown in FIG. On the center side where the press temperature is low and the time is short, the melt rate of each resin layer can be uniformly aligned. Thereby, it can melt | dissolve and adhere suitably (more uniformly) within predetermined | prescribed hot press time, without changing the material and thickness of each resin layer, and ion permeability in the said resin layer in the center part and the edge part of a lamination direction Can also reduce the difference. That is, even if the temperature of a hot press is low in the center side of a lamination direction, it can adhere at the same timing as an edge part. As a result, it is excellent in the point that the reaction distribution nonuniformity for every unit cell layer (single cell) 19 can be prevented, and the durability of the whole laminated structure battery 10 can be improved significantly (refer capacity retention rate of Table 2 of an Example). . In addition, in this embodiment, the weight of the single coating part which comprises the coating part of a resin layer is made into the center side <end side in a lamination direction, without changing the material and thickness of the coating part of a resin layer. Therefore, unlike changing melting | fusing point from the short side and the center side, the same material is used for the coating part of the resin layer at the short side and the center side, and it is necessary to adjust the thickness of the resin layer (coating part) at the short side and the center side. It is also excellent in that the production process can be simplified. That is, in this embodiment, the weight of a desired single coating part (weight of dots or stripe weight) is merely applied by screening printing, for example, on the masking sheet which opened the resin layer forming material to the desired dot size. It is excellent in that it can be adjusted.

Here, as a range where the weight difference between the center side (middle side: inner side: center part) and the short side (outer side: end part) of the lamination direction of the resin layer 18 is suitable, what is necessary is just to achieve the objective of this embodiment, and to exhibit a desired effect. . That is, the porosity after melting is approximately equal in the single side which raises the weight of the resin layer of a single side, makes the weight of the center side low, and has the high hot press temperature and long time, and the central side with low hot press temperature and short time. By doing this, resistance between electrodes can be maintained uniformly even after hot pressing. Thereby, the resistance between electrodes can be kept uniform. Thereby, the reaction distribution nonuniformity for every unit cell layer (single cell) 19 can be prevented, and the durability of the whole laminated structure battery 10 can be improved.

Specifically, even if the above-described configuration (means) depends on the number of stacked single cells of the battery and the size of the electrode, the weight of a single coating portion constituting the coating portion of the resin layer on the single side in the stacking direction constitutes a single coating portion forming the central portion. What is necessary is just higher than the weight of the coating part. Preferably, it is preferable that the weight of the single coating part which comprises the coating part of the resin layer of the single side of a lamination direction is 1.1 to 2.5 times higher than the weight of the single coating part which comprises the coating part of the resin layer of the center part, More preferably, It is preferably 1.2 to 2.0 times higher. If the weight of a single coating portion of the resin layer on the single side in the stacking direction is 1.1 times or more, preferably 1.2 times or more higher than the weight of the single coating portion of the resin layer on the central portion, depending on the number of laminations, That is, even if the temperature of a hot press is low in the center side, the coating part of the resin layer on the center side can fully be adhere | attached at the same timing (short time) as the short side. Specifically, by the hot press, the melt rate of each resin layer can be uniformly aligned on the short side where the hot press temperature is high and the time is long, and the center side where the hot press temperature is low and the time is short. Therefore, even if the temperature of a hot press is low in the center side of a lamination direction, it can adhere at the same timing as an edge part, and it can prevent that a melt nonuniformity arises in a lamination direction. As a result, the above objects and effects can be sufficiently achieved. On the other hand, if the weight of a single coating portion of the resin layer on the single side is 2.5 times or less, preferably 2.0 times or less, than the weight of the single coating portion of the resin layer on the central portion, depending on the number of laminations, the following effects are obtained. Even if the temperature of the hot press is lowered at the center side, the coating portion of the resin layer at the center side can be sufficiently adhered at the same timing (short time) as the short side. Thereby, it can prevent that melt nonuniformity arises in a lamination direction. As a result, the above objects and effects can be sufficiently achieved. Specifically, the melt rate of each resin layer can be uniformly aligned on the short side where the hot press temperature is high and the time is long, and the center side where the hot press temperature is low and the time is short. Thereby, the reaction distribution nonuniformity for every single cell layer (monocell) can be prevented, and the durability of the whole laminated structure battery can be improved. Moreover, it can be adhere | attached in the state which maintained the desired thickness (area), without being crushed too much by the outer side by a hot press and being crushed. As a result, a good diffusion path for Li ions can be ensured, and generation of melt nonuniformity in the stacking direction can be prevented. As a result, the above objects and effects can be sufficiently achieved.

In addition, in this embodiment, it is preferable to make the gross weight of a coating part the same on a center side and a short side in a lamination direction. This can be formed, for example, by applying a resin layer forming material by screening printing on a masking sheet that has a desired dot size and a desired number of dots per cm 2. Thereby, it is excellent in the point which the adhesive force of each resin layer can be aligned, and can adhere | attach a single side and a center side more uniformly with the same adhesive force. Here, that the total weight of a coating part is the same in the lamination | stacking direction in the center side and a short side should just be the total weight of the coating part of the single side with respect to a center part in the range of 1 + -0.1 times. Preferably it is in the range of 1 ± 0.05 times. This takes into account the range in which manufacturing errors and obtained effects become equal.

(5) Current collector plate (current collector tab; external lead)

In the lithium ion secondary battery (laminated structure battery) 10, the current collector plates (current collector tabs) 25 and 27 may be used for the purpose of taking out a current to the outside of the battery. The current collector plates (current collector tabs) 25 and 26 are electrically connected to the current collectors 11 and 12, and are taken out to the outside of a laminate film or the like that is an exterior material.

The material constituting the current collecting plates 25 and 27 is not particularly limited and a known high conductive material conventionally used as a current collecting plate for a lithium ion secondary battery can be used. As a constituent material of the collector plate, for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. From the viewpoints of light weight, corrosion resistance and high electrical conductivity, aluminum, copper and aluminum are particularly preferable. In addition, in the positive electrode current collector plate (positive electrode tab) 25 and the negative electrode current collector plate (negative electrode tab) 27, the same material may be used, or different materials may be used.

(5a) Electrode (positive and negative electrodes) Terminal lead (inner lead)

In the stacked structure battery 10 shown in FIG. 1, the current collectors 11 and 12 are current collector plates (current collector tabs) 25 and 27 via negative electrode terminal leads and positive electrode terminal leads (not shown), respectively. And may be electrically connected to each other. only. A part of the collectors 11 and 12 can be extended like an electrode terminal lead (internal lead), and can be electrically connected to the collector plates (current collector tabs) 25 and 27 directly. Therefore, an electrode terminal lead (not shown) can be said to be an arbitrary structural member which should just be used suitably as needed.

As a material of a negative electrode and a positive electrode terminal lead, the lead used by a well-known laminated secondary battery can be used. In addition, the portion taken out from the battery packaging material may be covered with a heat-shrinkable heat-shrinkable tube or the like so as not to short-circuit by contact with peripheral devices, wiring, or the like, thereby affecting the product (for example, automobile parts, especially electronic devices, etc.). desirable.

(6) Battery exterior material

As the battery packaging material, a conventionally known metal can case can be used. In addition, you may pack the power generation element 21 using the laminated film 29 as shown in FIG. 1 as an exterior material. The laminate film can be configured, for example, with a three-layer structure in which polypropylene, aluminum, and nylon are laminated in this order. By using such a laminated film, it is possible to easily open the casing, add the capacity recovery material, and re-seal the casing. In addition, a laminate film jacket is preferable from the viewpoints of high output and cooling performance, and suitability for batteries for large-sized appliances for EV and HEV.

The lithium ion secondary battery 10 of the said laminated structure can be manufactured by a conventionally well-known manufacturing method.

[Outline structure of lithium ion secondary battery]

4 is a perspective view showing the appearance of a flat laminated (laminated structure) lithium ion secondary battery which is a typical embodiment of a laminated structure battery.

As shown in FIG. 4, in the flat-layered lithium ion secondary battery 30, it has a rectangular flat shape, and on both sides thereof, the positive electrode tab 38 and the negative electrode tab 39 for extracting power are drawn out. do. The power generation element 37 is enclosed by the battery sheath 32 of the lithium ion secondary battery 30, and the surroundings are heat-sealed, and the power generation element 37 externally the positive electrode tab 38 and the negative electrode tab 39. Sealed in the drawn state. Here, the power generation element 37 corresponds to the power generation element 21 of the stacked lithium ion secondary battery (laminated structure battery) 10 shown in FIG. 1 described above. The power generation element 37 is formed by stacking a plurality of unit cell layers (single cells) 19 composed of a positive electrode, an electrolyte layer, and a negative electrode.

In addition, the extraction of the tabs 38 and 39 shown in FIG. 4 is not particularly limited. The positive electrode tab 38 and the negative electrode tab 39 may be taken out from the same side, or the positive electrode tab 38 and the negative electrode tab 39 may be divided into a plurality, respectively, and may be taken out from each side. It is not limited to what is shown in.

The lithium ion secondary battery (laminated structure cell) 10 is a large-capacity power source for an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, a hybrid fuel cell vehicle, and the like, and is used for driving a vehicle in which solid energy density and solid power density are required. It can use suitably for a power supply or an auxiliary power supply.

In addition, although the said embodiment illustrated the laminated lithium ion secondary battery as a laminated structure battery, it is not limited to this, It is applicable to other types of secondary batteries and also a primary battery.

The above-described laminated structure battery of the present embodiment has the following effects.

In this embodiment, the resin layer is constituted to have a coating portion and an uncoated portion, and the inner side reduces the area of a single coating portion, so that the hot side has a high hot press temperature and a long time, and a hot side has a low hot press temperature and a short time. Melt rate can be uniformly aligned at. That is, even if the temperature of a hot press is low in the center side of a lamination direction, it can adhere at the same timing as an edge part.

As a result, the reaction distribution nonuniformity for every unit cell layer (monocell) can be prevented, and the durability of the whole laminated structure battery can be improved. Uniform output can be obtained for each unit cell to be stacked, and battery durability can be improved.

In addition, the resin layer has a coating portion and an uncoated portion, and by reducing the weight of a single coating portion at the center side, the hot press can be bonded at the same timing as the end, even if the temperature of the hot press is low.

In addition, since the same material can be used for the coating part of each resin layer in addition to the said effect, by making the weight of a single coating part into center side <single side in a lamination direction, a production process can be simplified.

By keeping the shape of the separator lower than the melting point of the separator by lowering the melting point of the separator, the surface of the coating portion of the resin layer can be softened to give adhesion to the electrode-separator. Therefore, since battery reaction is not inhibited as much as possible, an effect can be more exerted on an output characteristic.

[Example]

Although this invention is demonstrated in more detail using the following example and a comparative example, it is not limited to a following example at all.

1. Fabrication of positive electrode

LiMn ₂ O ₄ (average particle diameter (20 μm)) as a positive electrode active material, acetylene black as a conductive aid, and polyvinylidene fluoride (PVDF) as a binder were mixed in a mass ratio of positive electrode active material: conductive aid: binder = 90: 5: 5 A positive electrode slurry was obtained.

The slurry was coated with NMP (N-methyl-2-pyrrolidone) to adjust the viscosity so that the amount of active material per unit area on both sides of the Al foil (thickness (15 μm) was 20 mg / cm 2 on one side. Subsequently, the thickness of the positive electrode (total thickness of the positive electrode current collector + positive electrode active material layer (both sides)) was processed to a thickness of 95 μm using a roll press.

2. Fabrication of negative electrode

Natural graphite (average particle diameter 20 mu m) as a negative electrode active material and polyvinylidene fluoride (PVDF) as a binder were mixed in a mass ratio of negative electrode active material: binder = 95: 5 to obtain a negative electrode slurry.

The slurry was coated with NMP to adjust the viscosity so that the amount of active material per unit area was 8 mg / cm 2 on one side on both sides of Cu foil (thickness 10 µm). After sufficiently drying, the thickness of the negative electrode (total thickness of the negative electrode current collector + negative electrode active material layer (both sides)) was processed to a thickness of 70 μm using a roll press.

3. Preparation of Separator + Resin Layer (A) (hereinafter referred to simply as Resin Separator A)

To the laminated microporous film of PE and PP (thickness 20 micrometers, porosity 50%, melting point 140 degreeC), the resin layer forming material which mixed PVDF and NMP in mass ratio 1: 9 is spread | discovered by the space | interval in Table 1, and apply | coat and apply. Resin separator A was produced by forming the resin layer (A) which has a dot-shaped coating part. The thickness of the dot-shaped coating part of the resin layer (A) was 2 micrometers, and melting | fusing point was 100 degreeC.

4. Preparation of Separator + Resin Layer (B) (hereinafter referred to simply as Resin Separator B)

In the laminated microporous film of PE and PP (thickness 20 micrometers, porosity 50%, melting | fusing point 140 degreeC), the resin layer forming material which mixed PVDF and NMP in mass ratio 1: 9 is spread | discovered by the space | interval in Table 1, and apply | coat and apply. Resin separator B was produced by forming the resin layer (B) which has a dot-shaped coating part. The thickness of the dot-shaped coating part of the resin layer (B) was 2 micrometers, and melting | fusing point was 100 degreeC.

5. Preparation of Separator + Resin Layer (C) (hereinafter referred to simply as Resin Separator C)

In the laminated microporous film of PE and PP (thickness 20 micrometers, porosity 50%, melting | fusing point 140 degreeC), the resin layer forming material which mixed PVDF and NMP in mass ratio 1: 9 is spread | discovered by the space | interval in Table 1, and apply | coat and apply. Resin separator C was produced by forming the resin layer (C) which has a dot-shaped coating part. The thickness of the dot-shaped coating part of the resin layer (C) was 2 micrometers, and melting | fusing point was 100 degreeC.

6. Preparation of Separator + Resin Layer (D) (hereinafter referred to simply as Resin Separator D)

In the laminated microporous film of PE and PP (thickness 20 micrometers, porosity 50%, melting | fusing point 140 degreeC), the resin layer forming material which mixed PVDF and NMP in mass ratio 1: 9 is spread | discovered by the space | interval in Table 1, and apply | coat and apply. Resin separator D was produced by forming the resin layer (D) which has a dot-shaped coating part. The thickness of the dot-shaped coating part of the resin layer (D) was 2 micrometers, and melting | fusing point was 100 degreeC.

In addition, the resin layer forming material of resin separators A-D was apply | coated by the screening printing on the masking sheet opened so that it might have the dot size of Table 1 and the number of dots per cm <2>.

Each electrode (positive electrode and negative electrode) was sufficiently dried, and the strength of the resin layer (coating part) was measured by a 90 ° peel test. In addition, the dotted amount of the dot-shaped coating part (PVDF binder) of each resin layer (the dot shape is the size of one side of the cross-sectional shape (square) of a single coating part (square column), the number of dots per 1 cm 2, and the peel strength test The results are as in Table 1 below.

Dot size / pcs Dot Count / ㎠ Area of the single coating part (contrast ratio) constituting the coating part of the resin layer Weight of single coating portion (relative contrast ratio) constituting the coating portion of the resin layer Peel test (N / m) Resin Separator A 0.5 8 One One 3.2 Resin Separator B 0.6 5.5 1.44 1.44 3.1 Resin Separator C 0.8 3 2.56 2.56 3.3 Resin Separator D 1 2 4 4 3.2

In Table 1, the area (weight) of the single coating part constituting the coating part of the resin layer is relative to the other resin separators B to D when the resin separator A uses the area (weight) of the single coating part as 1 (reference). An area (weight) ratio (relative ratio) is shown.

The "dot size / piece" of Table 1 has the dot shape which comprises the coating part of the resin layer for every resin separators A-D, and the surface shape (= square (□) of the prismatic dot (single coating part) of a single coating part. Represents the size (unit: mm) of one side.

7. Description of Examples

The laminated structure battery (cell stack) which produced the 5-layer single cell layer (single cell) laminated | stacked was combined, combining the structural site | part (member) of the said single cell layer (single cell) of said 1-6.

As the positive electrode and the negative electrode of each unit cell layer (single cell) of all the examples, the members produced in the above 1 and 2 were used.

In addition, the lamination number of each single cell of the laminated structure battery in which five single cell layers (single cells) are laminated is set to 1 to 5 in order from the bottom.

Example 1

Resin separator B was used for the 1st stage, 2nd stage, 4th stage, and 5th stage, and resin separator A was used for the 3rd stage.

Example 2

Resin separator C was used for the 1st stage and 5th stage, resin separator B was used for the 2nd stage, and 4th stage, and resin separator A was used for the 3rd stage.

Example 3

Resin separator D was used for the 1st stage and 5th stage, resin separator C was used for the 2nd stage, and 4th stage, and resin separator B was used for the 3rd stage.

Comparative Example 1

Resin separator A was used for all the layers (1st-5th stage).

Comparative Example 2

Resin separator B was used for all the layers (1st-5th stage).

Comparative Example 3

Resin separator C was used for all the layers (1st-5th stage).

Comparative Example 4

Resin separator D was used for all the layers (1st-5th stage).

8. Fabrication of Laminated Structure Cells

In the above procedure, the positive electrode, the negative electrode, and the resin separator A or D are cut to be 20 cm (vertical, 20 cm square), and the single cell layer (single cell) is arranged in five layers, and the tabs of each layer are connected to form a parallel type ( The power generation elements of the laminated structure battery of the internal parallel connection type) were stacked. At this time, the said resin separators A-D were arrange | positioned so that the resin layer side may adhere | attach on the surface of a negative electrode (active material layer) in all the unit cell layers (single cell). From the vertical direction of the power generating element 21 using the heat press apparatus (pressing jig) 20 shown in FIG. 5, in order to adhere | attach (heat-fusion) the dot-shaped coating part of the resin layer of resin separators A-D. A constant pressure load was applied while hot (hot press). The load at this time was 10 MPa, the temperature of the apparatus (jig) 20 was 95 degreeC, and the press time was 5 minutes.

Each power generation element 21 (laminated body) was placed in an aluminum laminate outer package, a desired electrolyte solution was injected, followed by vacuum sealing, to fabricate a laminated structure battery. The mixed solution (molar ratio of 5: 5) of EC and DEC containing 1 M LiPF ₆ was used for electrolyte solution at this time.

9. Evaluation Method

The cycle test (durability test) was done under 50 degreeC storage using the laminated structure battery produced by the said procedure. Cycle conditions were 400 cycles between 4.2V-3.0V at 1C rate.

10. Results

The capacity retention rate (%) before and after the endurance test is shown in Table 2 below.

Capacity retention rate (%) = (discharge capacity (Ah) of the 400th cycle) / (discharge capacity (Ah) of the 1st cycle) x 100.

1st stage 2nd step 3rd stage 4th stage 5th step Capacity maintenance rate (400cyc) Example 1 B B A B B 76% Example 2 C B A B C 78% Example 3 D C B C D 79% Comparative Example 1 A A A A A 68% Comparative Example 2 B B B B B 67% Comparative Example 3 C C C C C 68% Comparative Example 4 B B B B B 65%

A-D in Table 2 shows resin separators A-D used for each unit cell layer (1st-5th stage) of each Example and a comparative example by symbol.

From the results shown in Tables 1 and 2, the capacity retention ratio of 76 to 79% could be ensured by gradating the area of a single coating portion of the resin layer for each of the unit cell layers (single cells) to be laminated as in Examples 1 to 3. . Moreover, compared with the capacity retention ratio (65-68%) of the laminated structure battery which did not gradient the area of the single coating part of the resin layer for every single cell layer (single cell) laminated like Comparative Examples 1-4, Examples 1-4. In the laminated structure battery of 3, it was confirmed that the durability was improved. In addition, in each Example and the comparative example, when the coating part of a resin layer consists of several single coating part (resin separators A-C), each area of the single coating part (and weight) is the same as Table 1, respectively. What was produced so that it might become (the same shape) was used. In addition, as shown in Table 1, the coating part of the resin layer of each Example and the comparative example uses what was produced so that the total area (and gross weight) in the surface of a coating part might become the same on the center side and the short side in a lamination direction. .

In addition, as can be seen from Tables 1 and 2, in the present invention, the area (and weight) of the single coating portion constituting the coating portion of the single-celled resin layer from the center side may be gradientd. It may be gradient-graded so that the area (and weight) of the single coating part which comprises the coating part of a resin layer may change for every several cell number. For example, when five unit cell layers (single cells) are laminated in the same manner as in the embodiment, the area (and weight) of the single coating portion constituting the coating portion of the resin layer may be in the order of D> C> B> A. Moreover, the area (and weight) of the single coating part which comprises the coating part of the resin layer includes the form which changes as follows from a single side in order. C> B> A <B <C, D> B> A <B <D, D> C> A <C <so that the area (also the weight) of the single coating part constituting the coating part of the resin layer is changed for each single cell. It may be gradientd as D, D> C> B <C <D. Moreover, B = B> A <B = B, C = C> A <C = C, D = D> A so that the area (also the weight) of the single coating part constituting the coating part of the resin layer is changed for every single cell. <D = D, C = C> B <C = C, D = D> B <D = D, D = D> C <D = D, B> A = A = A <D, C> A = A = A <C, D> A = A = A <D, C> B = B = B <C, D> B = B = B <D, D> C = C = C <D It may be done. However, as long as the area (and weight) of the single coating part constituting the coating part of the resin layer of the single cell satisfies the center side <end side, it is not limited to these.

10, 30 laminated structure lithium ion secondary battery
11 positive electrode current collector
12 negative current collector
13 positive electrode active material layer
15 negative electrode active material layer
17 Electrolyte Layer (Separator)
18 resin layer
19 Single Cell Layer (Single Cell)
20 Heat Press Device (Push Jig)
21, 37 power generation elements
25 positive electrode current collector
27 negative current collector
29, 32 battery case
31, electrode (separator) surface
33a striped coating
33b dot-shaped coating
35 uncoated
38 positive electrode tap
39 negative electrode tab

Claims (4)

In a laminated structure battery having an electrolyte layer including a positive electrode, a negative electrode, and a separator, and stacking three or more layers of a single cell layer formed by opposing a positive electrode and a negative electrode through an electrolyte layer,
There is also a resin layer formed by adhering at least one of the stationary poles and the separator between at least one of the stationary poles and the separator,
The resin layer has a coating portion and an uncoated portion,
The area of a single coating part (if the coating part is composed of a plurality of single coating parts, each of which is an average value of the areas of the single coating part) is a center side <single side in the lamination direction. The method of claim 1,
The laminated structure battery in which the total area in the surface of a coating part is the same on the center side and the short side in a lamination direction. 3. The method according to claim 1 or 2,
The weight of the said single coating part (when a coating part consists of a plurality of single coating parts, it is set as the average value of the weight of each single coating part) is a laminated structure battery characterized by the center side <single side in a lamination direction. 3. The method according to claim 1 or 2,
Melting | fusing point of the coating part of the said resin layer is lower than melting | fusing point of the said separator, The laminated structure battery characterized by the above-mentioned.

Images