Non-aqueous electrolyte energy storage element and method for manufacturing a non-aqueous electrolyte energy storage element

Abstract

The present invention provides a non-aqueous electrolyte energy storage element equipped with bipolar electrodes and having high manufacturing efficiency, as well as a method for manufacturing such a non-aqueous electrolyte energy storage element. [Solution] A non-aqueous electrolyte energy storage element according to one aspect of the present invention comprises a substrate, an electrode having a positive electrode active material layer laminated on one side of the substrate, and a negative electrode active material layer laminated on the other side of the substrate, wherein at least one of the positive electrode active material layer and the negative electrode active material layer contains a fibrillated binder.

Description

[Technical Field]

[0001] This invention relates to a non-aqueous electrolyte energy storage element and a method for manufacturing a non-aqueous electrolyte energy storage element. [Background technology]

[0002] Non-aqueous electrolyte secondary batteries, such as lithium-ion secondary batteries, are widely used in electronic devices such as personal computers and communication terminals, as well as automobiles, due to their high energy density. Generally, non-aqueous electrolyte secondary batteries consist of a pair of electrically isolated electrodes and a non-aqueous electrolyte interposed between these electrodes. They are configured to charge and discharge by transferring charge-transporting ions between the two electrodes. Besides non-aqueous electrolyte secondary batteries, capacitors such as lithium-ion capacitors and electric double-layer capacitors are also widely used as non-aqueous electrolyte energy storage elements.

[0003] One example of an electrode constituting a non-aqueous electrolyte energy storage element is a so-called bipolar electrode, in which a positive electrode active material layer is formed on one side of a single substrate and a negative electrode active material layer is formed on the other side (Patent Document 1). Non-aqueous electrolyte energy storage elements equipped with bipolar electrodes have advantages such as low resistance within the energy storage element and excellent input / output characteristics. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-216846 [Overview of the project] [Problems that the invention aims to solve]

[0005] Bipolar electrodes typically consist of multiple stacked layers, with the positive electrode active material layer and the negative electrode active material layer facing each other with a separator in between. In non-aqueous electrolyte energy storage elements equipped with bipolar electrodes, non-aqueous electrolyte is supplied to the spaces between adjacent bipolar electrodes, and these spaces are sealed to prevent short circuits. In other words, non-aqueous electrolyte energy storage elements equipped with bipolar electrodes typically have multiple sealed spaces to which non-aqueous electrolyte is supplied. In this case, when manufacturing non-aqueous electrolyte energy storage elements, it is necessary to repeatedly inject non-aqueous electrolyte into the spaces between bipolar electrodes and then seal the injection port to prevent leakage of the non-aqueous electrolyte. Such a process tends to be complicated, and there is room for improvement in terms of manufacturing efficiency for non-aqueous electrolyte energy storage elements equipped with bipolar electrodes.

[0006] The present invention has been made based on the circumstances described above, and aims to provide a non-aqueous electrolyte energy storage element equipped with bipolar electrodes and with high manufacturing efficiency, as well as a method for manufacturing such a non-aqueous electrolyte energy storage element. [Means for solving the problem]

[0007] A non-aqueous electrolyte energy storage element according to one aspect of the present invention comprises a substrate, an electrode having a positive electrode active material layer laminated on one side of the substrate, and a negative electrode active material layer laminated on the other side of the substrate, wherein at least one of the positive electrode active material layer and the negative electrode active material layer contains a fibrillated binder.

[0008] A method for manufacturing a non-aqueous electrolyte energy storage element according to another aspect of the present invention comprises manufacturing an electrode having a substrate, a positive electrode active material layer laminated on one side of the substrate, and a negative electrode active material layer laminated on the other side of the substrate, wherein at least one of the positive electrode active material layer and the negative electrode active material layer includes a fibrillated binder. [Effects of the Invention]

[0009] The non-aqueous electrolyte storage element according to one aspect of the present invention includes a bipolar electrode and has high manufacturing efficiency. Further, according to the method for manufacturing a non-aqueous electrolyte storage element according to another aspect of the present invention, a non-aqueous electrolyte storage element including a bipolar electrode and having high manufacturing efficiency can be provided.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a non-aqueous electrolyte storage element according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic perspective view showing an electrode included in the non-aqueous electrolyte storage element according to FIG. 1. [Figure 3] FIG. 3 is a schematic side view showing an example of a procedure for manufacturing an electrode in the method for manufacturing a non-aqueous electrolyte storage element according to an embodiment of the present invention. [Figure 4] FIG. 4 is a schematic view showing a power storage device including a plurality of non-aqueous electrolyte storage elements according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0011] First, an overview of the non-aqueous electrolyte storage element and the method for manufacturing the non-aqueous electrolyte storage element disclosed in this specification will be described.

[0012] (1) The non-aqueous electrolyte storage element according to one aspect of the present invention includes an electrode having a base material, a positive electrode active material layer laminated on one surface of the base material, and a negative electrode active material layer laminated on the other surface of the base material, and at least one of the positive electrode active material layer and the negative electrode active material layer contains a fibrillated binder.

[0013] The electrode included in the non-aqueous electrolyte storage element described in (1) above is a so-called bipolar electrode in which a positive electrode active material layer is formed on one surface of a single substrate and a negative electrode active material layer is formed on the other surface. A non-aqueous electrolyte storage element including a bipolar electrode usually has a sealed space supplied with a non-aqueous electrolyte. This space is, for example, the space between one positive electrode active material layer and one negative electrode active material layer laminated so as to face each other with a separator or the like interposed therebetween (see FIG. 1). During manufacturing, if the above space is small, it is likely to be difficult to inject and seal the non-aqueous electrolyte. Conversely, if the above space is large, it is considered that the non-aqueous electrolyte can be easily injected and sealed. In this regard, since the electrode included in the non-aqueous electrolyte storage element described in (1) above contains a fibrillated binder (hereinafter also referred to as a "fibrillated binder"), the fibers of the binder entangle with the active material and the like, so that an active material layer with good binding properties and difficult to cause slippage of the active material can be formed. In other words, the thickness of the active material layer can be easily increased. Further in other words, it is easy to increase the space where the non-aqueous electrolyte is supplied in the direction in which the active material layers are laminated. Therefore, the non-aqueous electrolyte storage element described in (1) above can easily inject and seal the non-aqueous electrolyte during manufacturing. Also, when a configuration is adopted in which a plurality of bipolar electrodes are laminated, if the thickness of the active material layer is large, the output performance can be ensured with a relatively small number of laminations. For this reason, the non-aqueous electrolyte storage element described in (1) above has a small number of the above spaces for sealing the non-aqueous electrolyte, and the number of times of injecting and sealing the non-aqueous electrolyte is likely to decrease during manufacturing. From the above points, the non-aqueous electrolyte storage element described in (1) above includes a bipolar electrode and has high manufacturing efficiency.

[0014] (2) The non-aqueous electrolyte storage element described in (1) above may include a fibrillated binder in the positive electrode active material layer, and the average thickness of one layer of the positive electrode active material layer may be 100 μm or more.

[0015] The non-aqueous electrolyte energy storage element described in (2) above has a sufficiently large average thickness for one positive electrode active material layer, and also contains a fibrillation binder that makes it easy to increase the thickness of the positive electrode active material layer, thus resulting in higher manufacturing efficiency. The term "average" refers to the average value of measurements taken at any five locations, and the same applies to subsequent descriptions in this specification.

[0016] (3) The non-aqueous electrolyte energy storage element described in (1) or (2) above may include a fibrillated binder in the negative electrode active material layer, and the average thickness of one negative electrode active material layer may be 100 μm or more.

[0017] The non-aqueous electrolyte energy storage element described in (3) above has a sufficiently large average thickness for one negative electrode active material layer, and also contains a fibrillation binder that makes it easy to increase the thickness of the negative electrode active material layer, thus resulting in higher manufacturing efficiency.

[0018] (4) In the non-aqueous electrolyte energy storage element described in any of (1) to (3) above, the positive electrode active material layer may have a thinned region at the outer edge when viewed in the stacking direction, where the average thickness is smaller than that of the central portion.

[0019] The non-aqueous electrolyte energy storage element described in (4) above has a thinned-layer region at the outer edge of the positive electrode active material layer, which suppresses the non-uniform deposition of charge transport ions such as lithium ions as metal at the outer edge of the negative electrode active material layer, etc. Furthermore, the thinned-layer region can be easily formed by pressing, etc. Therefore, it is possible to easily increase manufacturing efficiency while improving the quality of the non-aqueous electrolyte energy storage element.

[0020] The term "peripheral edge" refers to a region of the positive electrode active material layer (or negative electrode active material layer) that occupies a uniform width inward from the outer edge when viewed in the stacking direction, and whose area is 30% of the total area of ​​the positive electrode active material layer (or negative electrode active material layer). The term "central region" refers to the region of the positive electrode active material layer other than the outer edge.

[0021] (5) A non-aqueous electrolyte energy storage element according to any of (1) to (4) above, comprising at least two adjacent electrodes and a separator having a resin layer located on the outermost surface, wherein the separator is disposed between a first positive electrode active material layer of the first electrode and a second negative electrode active material layer of the second electrode facing the first positive electrode active material layer, and the resin layer of the separator and the layer of the first positive electrode active material layer and the second negative electrode active material layer that includes the fibrillated binder are in close contact.

[0022] In the non-aqueous electrolyte energy storage element described in (5) above, the resin layer of the separator and the first positive electrode active material layer and the second negative electrode active material layer containing the fibrillated binder are in close contact, so the movement of the separator within the non-aqueous electrolyte energy storage element is suppressed by frictional force. As a result, the quality of the non-aqueous electrolyte energy storage element can be improved while easily increasing manufacturing efficiency.

[0023] (6) In the non-aqueous electrolyte energy storage element described in (5) above, the adjacent electrodes may be pressed in the stacking direction.

[0024] In the non-aqueous electrolyte energy storage element described in (6) above, the movement of the separator within the non-aqueous electrolyte energy storage element can be further suppressed by frictional force because adjacent electrodes are pressed in the stacking direction.

[0025] (7) A method for manufacturing a non-aqueous electrolyte energy storage element according to another aspect of the present invention comprises manufacturing an electrode having a substrate, a positive electrode active material layer laminated on one side of the substrate, and a negative electrode active material layer laminated on the other side of the substrate, wherein at least one of the positive electrode active material layer and the negative electrode active material layer includes a fibrillated binder.

[0026] According to the method for manufacturing a non-aqueous electrolyte energy storage element described in (7) above, it is possible to manufacture a non-aqueous electrolyte energy storage element equipped with a bipolar electrode that includes a fibrillated binder and can easily increase the thickness of the active material layer. Therefore, according to the method for manufacturing a non-aqueous electrolyte energy storage element described in (7) above, it is possible to provide a non-aqueous electrolyte energy storage element equipped with a bipolar electrode and with high manufacturing efficiency.

[0027] (8) In the method for manufacturing a non-aqueous electrolyte energy storage element described in (7) above, the production of the electrodes may include simultaneously laminating the positive electrode active material layer and the negative electrode active material layer onto the substrate.

[0028] According to the method for manufacturing a non-aqueous electrolyte energy storage element described in (8) above, since the electrode fabrication involves simultaneously laminating the positive electrode active material layer and the negative electrode active material layer onto the substrate, it is possible to provide a non-aqueous electrolyte energy storage element with higher manufacturing efficiency. Furthermore, since at least one of the positive electrode active material layer and the negative electrode active material layer contains a fibrillation binder, it is easy to simultaneously laminate the positive electrode active material layer and the negative electrode active material layer onto the substrate, and it is possible to provide a non-aqueous electrolyte energy storage element with higher manufacturing efficiency.

[0029] The following describes in detail a non-aqueous electrolyte energy storage element, a method for manufacturing a non-aqueous electrolyte energy storage element, an energy storage device, and other embodiments according to one embodiment of the present invention.

[0030] [Non-aqueous electrolyte energy storage element] The non-aqueous electrolyte energy storage element 10 in Figure 1 comprises a substrate 111 and a plurality of electrodes 11 (at least two) (hereinafter also referred to as "bipolar electrodes 11") having a positive electrode active material layer 112 laminated on one side of the substrate 111 and a negative electrode active material layer 113 laminated on the other side of the substrate 111. In this embodiment, it is preferable that both the positive electrode active material layer 112 and the negative electrode active material layer 113 of all bipolar electrodes 11 contain a fibrillation binder. Although not particularly limited, Figure 1 shows a configuration with two bipolar electrodes 11 as an example. The number of bipolar electrodes 11 may be, for example, three or more. The non-aqueous electrolyte energy storage element 10 has high manufacturing efficiency.

[0031] The non-aqueous electrolyte energy storage element 10 further comprises a positive electrode 12 having a positive electrode substrate 121 and a positive electrode active material layer 122 and facing the negative electrode active material layer 113 of the outermost bipolar electrode 11, a negative electrode 13 having a negative electrode substrate 131 and a negative electrode active material layer 132 and facing the positive electrode active material layer 112 of the outermost bipolar electrode 11, a plurality of separators 14, a non-aqueous electrolyte 15, and a container 16 that houses the plurality of bipolar electrodes 11, the positive electrode 12, the negative electrode 13, the plurality of separators 14, and the non-aqueous electrolyte 15. The plurality of bipolar electrodes 11 are stacked with the separators 14 in between so that the positive electrode active material layer 112 (first positive electrode active material layer) of the first bipolar electrode 11 and the negative electrode active material layer 113 (second negative electrode active material layer) of the second bipolar electrode 11 face each other. Of the stacked bipolar electrodes 11, the outermost bipolar electrode 11 with its positive electrode active material layer 112 facing outwards faces the negative electrode 13's negative electrode active material layer 132 with a separator 14 in between, and the outermost bipolar electrode 11 with its negative electrode active material layer 113 facing outwards faces the positive electrode 12's positive electrode active material layer 122 with a separator 14 in between. Here, "outside" means the outside of the non-aqueous electrolyte energy storage element 10. In other words, the positive electrode 12 and the negative electrode 13 are arranged so as to sandwich the stack in which the bipolar electrodes 11 and separators 14 are stacked alternately. The substrates 111 of adjacent bipolar electrodes 11, the substrate 111 of the bipolar electrode 11 located in the outermost layer with the negative electrode active material layer 113 facing outwards, and the positive electrode substrate 121 of the positive electrode 12, as well as the substrate 111 of the bipolar electrode 11 located in the outermost layer with the positive electrode active material layer 112 facing outwards, and the negative electrode substrate 131 of the negative electrode 13, each form a space into which the non-aqueous electrolyte 15 is supplied. The non-aqueous electrolyte 15 is supplied to each of these multiple spaces. The non-aqueous electrolyte 15 is sealed between the substrates (substrate 111, positive electrode substrate 121, and negative electrode substrate 131) and the inner surface of the container 16. In other words, the spaces between adjacent substrates 111, between substrate 111 and positive electrode substrate 121, and between substrate 111 and negative electrode substrate 131 each form multiple sealed spaces into which the non-aqueous electrolyte 15 is sealed. At least a portion of the non-aqueous electrolyte is usually present in a state where it has permeated the positive electrode active material layer 112, the negative electrode active material layer 113, the positive electrode active material layer 122, and the negative electrode active material layer 132.

[0032] The non-aqueous electrolyte energy storage element 10 may further comprise other components besides the bipolar electrode 11, positive electrode 12, negative electrode 13, separator 14, non-aqueous electrolyte 15, and container 16. Examples of other components include a positive electrode lead, a positive electrode external terminal, a negative electrode lead, and a negative electrode external terminal. The positive electrode lead and negative electrode lead are housed inside the container 16 (not shown). The positive electrode external terminal and negative electrode external terminal are provided outside the container 16 (not shown). The positive electrode 12 is electrically connected to the positive electrode external terminal via the positive electrode lead. The negative electrode 13 is electrically connected to the negative electrode external terminal via the negative electrode lead.

[0033] The non-aqueous electrolyte energy storage element 10 of the present invention may also be a non-aqueous electrolyte secondary battery. The following will detail the main components constituting the non-aqueous electrolyte energy storage element 10 according to one embodiment of the present invention, focusing primarily on the case where the non-aqueous electrolyte energy storage element 10 is a non-aqueous electrolyte secondary battery (particularly a lithium-ion secondary battery), but this is not intended to limit the scope of application of the present invention. Note that the lower and upper limits of each numerical range described in the embodiments of the present invention can be combined in any way.

[0034] In this embodiment, the substrate 111 of the bipolar electrode 11 is constructed by laminating a positive electrode substrate 111a and a negative electrode substrate 111b. One side of the substrate 111 is formed by the positive electrode substrate 111a, and the other side of the substrate 111 is formed by the negative electrode substrate 111b. The positive electrode active material layer 112 is laminated on the positive electrode substrate 111a, and the negative electrode active material layer 113 is laminated on the negative electrode substrate 111b.

[0035] As described above, in this embodiment, both the positive electrode active material layer 112 and the negative electrode active material layer 113 of all bipolar electrodes 11 contain a fibrillation binder. By including a fibrillation binder in both the positive electrode active material layer 112 and the negative electrode active material layer 113 of all bipolar electrodes 11 in this way, the advantages of the present invention can be significantly obtained.

[0036] From the viewpoint of increasing the thickness of the bipolar electrode 11, the lower limit of the average thickness of the positive electrode active material layer 112 is preferably 100 μm, more preferably 120 μm, even more preferably 140 μm, and may be 160 μm, 180 μm, or 200 μm. On the other hand, from the viewpoint of keeping the thickness of the bipolar electrode 11 within an appropriate range, the upper limit of the average thickness of the positive electrode active material layer 112 is preferably 400 μm, more preferably 350 μm, and even more preferably 300 μm. Here, "average thickness" refers to the average thickness of the portion of the positive electrode active material layer 112 excluding the thinned-layer region 112a (central part) if the positive electrode active material layer 112 has a thinned-layer region 112a described later.

[0037] From the viewpoint of increasing the thickness of the bipolar electrode 11, the lower limit of the average thickness of the negative electrode active material layer 113 is preferably 100 μm, more preferably 120 μm, even more preferably 140 μm, and may be 160 μm, 180 μm, or 200 μm. On the other hand, from the viewpoint of keeping the thickness of the bipolar electrode 11 within an appropriate range, the upper limit of the average thickness of the negative electrode active material layer 113 is preferably 400 μm, more preferably 350 μm, and even more preferably 300 μm.

[0038] The lower limit of the average thickness of the bipolar electrode 11 is preferably 200 μm, more preferably 240 μm, even more preferably 280 μm, and may be 320 μm, 360 μm, or 400 μm. On the other hand, the upper limit of the average thickness of the bipolar electrode 11 is preferably 820 μm, more preferably 720 μm, and even more preferably 620 μm. Here, "average thickness" refers to the average thickness of the total thickness of the substrate 111, the central part of the positive electrode active material layer 112, and the negative electrode active material layer 113.

[0039] The positive electrode active material layer 112 and the negative electrode active material layer 113, which contain a fibrillated binder, may be dry-coated layers. By having the positive electrode active material layer 112 and the negative electrode active material layer 113 be dry-coated layers, it is possible to eliminate the need for equipment to volatilize the non-aqueous solvent when manufacturing the positive electrode active material layer 112 and the negative electrode active material layer 113, thereby reducing energy consumption during manufacturing.

[0040] As shown in Figure 2, in this embodiment, the bipolar electrode 11 is rectangular in shape when viewed in the stacking direction (hereinafter also simply referred to as "rectangular"). More specifically, the substrate 111 (positive electrode substrate 111a and negative electrode substrate 111b), positive electrode active material layer 112, and negative electrode active material layer 113 of the bipolar electrode 11 are rectangular in shape. One side of the substrate 111 (positive electrode substrate 111a) is covered by the positive electrode active material layer 112 without being substantially exposed, and the other side of the substrate 111 (negative electrode substrate 111b) is also covered by the negative electrode active material layer 113 without being substantially exposed. In other words, when viewed in the stacking direction, the outer edges of the substrate 111, the positive electrode active material layer 112, and the negative electrode active material layer 113 coincide, and when viewed in the stacking direction, the areas of the substrate 111, the positive electrode active material layer 112, and the negative electrode active material layer 113 are substantially the same. With the bipolar electrode 11 configured in this way, a method can be adopted for manufacturing the bipolar electrode 11 in which the positive electrode active material layer 112 and the negative electrode active material layer 113 are simultaneously laminated onto the substrate 111, and then the substrate 111, positive electrode active material layer 112, and negative electrode active material layer 113 are cut together into an appropriate shape and size, thereby increasing manufacturing efficiency. The method for manufacturing the bipolar electrode 11 will be described in detail later.

[0041] As shown in Figure 2, in this embodiment, the positive electrode active material layer 112 has a thinned-out region 112a at its outer edge when viewed in the stacking direction, with a smaller average thickness than the central portion. The thinned-out region 112a is a band-shaped region, more specifically an annular region, extending along the long and short sides of the positive electrode active material layer 112. In other words, the thinned-out region 112a is formed in a frame-like shape, surrounding the central portion of the positive electrode active material layer 112 when viewed in the stacking direction. By having a thinned-out region 112a in the positive electrode active material layer 112, it is possible to suppress the non-uniform deposition of charge transport ions such as lithium ions as metal at the outer edge of the negative electrode facing the thinned-out region 112a. The thinned-out region 112a can be easily formed by pressing the outer edge of the positive electrode active material layer 112 after stacking the positive electrode active material layer 112 on the substrate 111 (positive electrode substrate 111a). Furthermore, the effect of suppressing the non-uniform deposition of charge transport ions as metals is particularly pronounced when the area of ​​the positive electrode active material layer 112 and the area of ​​the negative electrode active material layer 113 are substantially the same, as in this embodiment.

[0042] From the viewpoint of further suppressing the non-uniform deposition of charge transport ions as metal at the outer peripheral edge of the negative electrode, it is preferable that the thinned layer region 112a is provided such that its average thickness gradually decreases toward the outer peripheral edge of the base material 111 (positive electrode base material 111a). Also from the same viewpoint, it is preferable that the average thickness of the thinned layer region 112a at the outer peripheral edge of the base material 111, i.e., the average thickness at the outer peripheral edge of the thinned layer region 112a, be 0.80 times or less the average thickness of the central part of the positive electrode active material layer 112, and may be, for example, 0.50 times or less, 0.10 times or less, 0.05 times or less, or 0.01 times or less.

[0043] As described above, the thinned-layer region 112a is a band-shaped region extending along the long and short sides. The average width of the thinned-layer region 112a formed along each long side of the positive electrode active material layer 112 is preferably 0.01 to 0.25 times, more preferably 0.03 to 0.20 times, and even more preferably 0.05 to 0.15 times, of the average length of the entire positive electrode active material layer 112 in the direction of the short side. The average width of the thinned-layer region 112a formed along each short side of the positive electrode active material layer 112 is preferably 0.01 to 0.25 times, more preferably 0.03 to 0.20 times, and even more preferably 0.05 to 0.15 times, of the average length of the entire positive electrode active material layer 112 in the direction of the long side. By having the above-mentioned average width of the thinned layer region 112a be within the above range, it is possible to achieve both improved input / output performance and suppression of non-uniform deposition of charge transport ions as metal at the outer edge of the negative electrode.

[0044] In this embodiment, the shape of the positive electrode substrate 121 of the positive electrode 12 in the stacking direction is the same as the shape of the positive electrode substrate 111a of the bipolar electrode 11, and the shape of the negative electrode substrate 131 of the negative electrode 13 in the stacking direction is the same as the shape of the negative electrode substrate 111b of the bipolar electrode 11. Furthermore, it is preferable that the configuration of the positive electrode active material layer 122 of the positive electrode 12 is the same as the preferred configuration of the positive electrode active material layer 112 of the bipolar electrode 11 described above. It is also preferable that the configuration of the negative electrode active material layer 132 of the negative electrode 13 is the same as the preferred configuration of the negative electrode active material layer 113 of the bipolar electrode 11 described above.

[0045] It is preferable that the separator 14 has a resin layer located on its outermost surface. It is even more preferable that both sides of the separator 14 facing the bipolar electrode 11 are formed of resin layers. Furthermore, it is preferable that the resin layer of the separator 14 is in close contact with the positive electrode active material layer 112 or the negative electrode active material layer 113 containing a fibrillated binder. It is even more preferable that both sides of the separator 14 are formed of resin layers, and that one side of the separator 14 is in close contact with the opposing positive electrode active material layer 112, and the other side of the separator 14 is in close contact with the opposing negative electrode active material layer 113. In this way, both sides of the separator 14 are formed of resin layers and are in close contact with the active material layers (positive electrode active material layer 112 and negative electrode active material layer 113) of the bipolar electrode 11, so that the movement of the separator 14 within the non-aqueous electrolyte energy storage element 10 is suppressed by frictional force. More specifically, a portion of the fibrillated binder contained in the active material layer of the bipolar electrode 11 becomes entangled in the pores of the resin layer of the separator 14, thereby suppressing the movement of the separator 14 within the non-aqueous electrolyte energy storage element 10. As a result, the quality of the non-aqueous electrolyte energy storage element 10 can be improved while easily increasing manufacturing efficiency.

[0046] The lower limit of the distance between adjacent bipolar electrodes 11 and substrates 111 is preferably 200 μm, more preferably 240 μm, even more preferably 280 μm, and may be 320 μm, 360 μm, or 400 μm. Manufacturing efficiency can be further increased by having a distance between substrates 111 that is greater than or equal to the above lower limit. On the other hand, the upper limit of the distance between substrates 111 is preferably 800 μm, more preferably 700 μm, and even more preferably 600 μm, in response to the demand for miniaturization of non-aqueous electrolyte energy storage elements.

[0047] In this embodiment, the container 16 has a pair of first inner walls extending along the long sides of the base material 111 and a pair of second inner walls extending along the short sides of the base material 111. The internal space of the container 16 is formed in a rectangular shape when viewed in the stacking direction by the pair of first inner walls and the pair of second inner walls. The pair of first inner walls are arranged without gaps with the pair of long sides of the base material 111, and the pair of second inner walls are arranged without gaps with the pair of short sides of the base material 111. Similarly, the pair of first inner walls are arranged without gaps with the pair of long sides of the positive electrode base material 121 and the negative electrode base material 131, and the pair of second inner walls are arranged without gaps with the pair of short sides of the positive electrode base material 121 and the negative electrode base material 131. In this way, the pair of first inner walls and the pair of second inner walls are arranged without gaps with the pair of long sides and the pair of short sides of the substrate of all electrodes, thereby sealing the non-aqueous electrolyte 15 supplied between the bipolar electrodes 11, between the bipolar electrode 11 and the positive electrode 12, and between the bipolar electrode 11 and the negative electrode 13.

[0048] The container 16 may have a plurality of injection ports (not shown) for supplying the non-aqueous electrolyte 15 into its internal space. Multiple injection ports may be provided, for example, between bipolar electrodes 11, between the bipolar electrode 11 and the positive electrode 12, and between the bipolar electrode 11 and the negative electrode 13, to supply the non-aqueous electrolyte 15. The multiple injection ports may be sealed after the non-aqueous electrolyte 15 has been supplied.

[0049] Adjacent bipolar electrodes 11 may be pressed in the stacking direction. Alternatively, adjacent bipolar electrodes 11 may be pressed in the stacking direction so that they are in close contact with each other. By pressing in the stacking direction in this way, the movement of the separator 14 within the non-aqueous electrolyte energy storage element 10 can be further suppressed by frictional force. Methods for pressing the bipolar electrodes 11 include restraining them so that a constant load is applied to the container.

[0050] The following provides a detailed explanation of the main components of the non-aqueous electrolyte energy storage element 10.

[0051] [Bipolar electrode 11] As described above, the bipolar electrode 11 comprises a base material 111, a positive electrode active material layer 112 laminated on one side of the base material 111, and a negative electrode active material layer 113 laminated on the other side of the base material 111. The base material 111 is formed by laminating a positive electrode base material 111a and a negative electrode base material 111b. The positive electrode active material layer 112 is laminated on the positive electrode base material 111a, and the negative electrode active material layer 113 is laminated on the negative electrode base material 111b. An intermediate layer may be formed between the positive electrode base material 111a and the positive electrode active material layer 112. An intermediate layer may also be formed between the negative electrode base material 111b and the negative electrode active material layer 113.

[0052] (base material) The positive electrode substrate 111a is conductive. In this specification, "having conductivity" means that the volume resistivity is 10 -2 This means that it is Ω·cm or less. The volume resistivity shall be the value measured in accordance with JIS-H-0505 (1975). On the other hand, in this specification, "not conductive" or "having (electrical) insulating properties" means that the above volume resistivity is 10 7 This means it is greater than or equal to Ω·cm.

[0053] Examples of materials for the positive electrode substrate 111a include metals such as aluminum, titanium, iron, and their alloys (stainless steel, etc.). Among these, aluminum or aluminum alloys are preferred from the viewpoint of high potential resistance, high electronic conductivity, and cost.

[0054] Examples of the form of the positive electrode substrate 111a include foil, a vapor-deposited film, etc., from the viewpoint of ensuring airtightness of the space in which the non-aqueous electrolyte 15 is supplied, with foil being preferred. The positive electrode substrate 111a may be, for example, aluminum foil or aluminum alloy foil.

[0055] The average thickness 111a of the positive electrode substrate 111a may be, for example, 3 μm or more and 50 μm or less. The lower limit of the average thickness of the positive electrode substrate 111a may be 5 μm, 8 μm, 10 μm, or 15 μm. The upper limit of the average thickness of the positive electrode substrate 111a may be 40 μm, 30 μm, 20 μm, or 15 μm.

[0056] The negative electrode substrate 111b is electrically conductive. Examples of materials for the negative electrode substrate 111b include metals such as copper, nickel, iron, and their alloys (such as stainless steel), as well as carbon materials. Among these, copper or copper alloys are preferred.

[0057] Examples of negative electrode substrates 111b include foil, vapor-deposited film, etc., from the viewpoint of ensuring airtightness of the space in which the non-aqueous electrolyte 15 is supplied, with foil being preferred. The negative electrode substrate 111b may be, for example, copper foil or copper alloy foil.

[0058] The average thickness of the negative electrode substrate 111b may be, for example, 2 μm or more and 35 μm or less. The lower limit of the average thickness of the negative electrode substrate 111b may be 3 μm, 4 μm, 5 μm, or 10 μm. The upper limit of the average thickness of the negative electrode substrate 111b may be 30 μm, 20 μm, 15 μm, or 10 μm.

[0059] (Middle class) The intermediate layer formed between the positive electrode substrate 111a and the positive electrode active material layer 112 includes, for example, a conductive agent and a binder. When the intermediate layer includes a conductive agent, the contact resistance between the positive electrode substrate 111a and the positive electrode active material layer 112 can be reduced. Examples of conductive agents and binders used in the intermediate layer include those similar to those used in the positive electrode active material layer 112, which will be described later. The configuration of the intermediate layer formed between the negative electrode substrate 111b and the negative electrode active material layer 113 is not particularly limited and can be selected from the configurations exemplified for the intermediate layer formed between the positive electrode substrate 111a and the positive electrode active material layer 112.

[0060] (Cathode active material layer 112) In this embodiment, the positive electrode active material layer 112 comprises a positive electrode active material and a fibrillation binder. The positive electrode active material layer 112 may optionally include a conductive agent, other binders other than the fibrillation binder, fillers, and other optional components. The positive electrode active material layer 112 may also be formed from a positive electrode mixture comprising the positive electrode active material, the fibrillation binder, and other optional components.

[0061] For the positive electrode active material, known positive electrode active materials can be used. For lithium-ion secondary batteries, materials capable of intercalating and releasing lithium ions are typically used. Examples of positive electrode active materials include lithium transition metal composite oxides, polyanion compounds, chalcogen compounds, sulfur-based materials, and lithium oxide. One or more positive electrode active materials can be used.

[0062] Examples of transition metal elements included in lithium transition metal composite oxides include nickel, cobalt, and manganese. Lithium transition metal composite oxides may also contain typical metal elements such as aluminum. Examples of lithium transition metal composite oxides include those having an α-NaFeO2 crystal structure and those having a spinel crystal structure.

[0063] Li 1+α Ma 1-α Examples include O2 (where Ma is a metallic element other than lithium, containing one or more transition metal elements, and 0 ≤ α < 1). It is preferable that Ma contains one or more of Ni, Co, and Mn. The total content of Ni, Co, and Mn relative to Ma ((Ni + Co + Mn) / Ma) is preferably 90 mol% or more, and more preferably 98 mol% or more.

[0064] Li β Examples include those represented as Mb2O4 (where Mb is a metallic element other than lithium, containing one or more transition metal elements, and 0 < β ≤ 1.2). Mb preferably contains Mn. The Mn content relative to Mb (Mn / Mb) is preferably 50 mol% or more, and more preferably 80 mol% or more.

[0065] A polyanion compound is a compound composed of a polyanion (i.e., a polyvalent oxoacid anion) and a cation. The polyanion compound preferably contains lithium cations and transition metal cations as cations. Examples of the polyanion compound include LiFePO4, LiMnPO4, LiMn x Fe 1-x PO4 (0 < x < 1), LiNiPO4, LiCoPO4, Li3V2(PO4)3, Li2MnSiO4, Li2CoPO4F, etc. The surface of the particles of the polyanion compound may be coated with another material (such as the carbon material described later).

[0066] Examples of the chalcogen compound include titanium disulfide, molybdenum disulfide, molybdenum dioxide, etc.

[0067] Examples of the sulfur-based material include elemental sulfur, metal sulfides such as lithium sulfide, organic disulfide compounds, organic sulfur compounds such as carbon sulfide compounds, etc.

[0068] Atoms or polyanions in these materials that are the positive electrode active material may be partially substituted with atoms or anion species composed of other elements. The surfaces of these materials may be coated with other materials.

[0069] The positive electrode active material is usually in particulate form. The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. Setting the average particle size of the positive electrode active material above the lower limit facilitates the manufacture and handling of the positive electrode active material. Setting the average particle size of the positive electrode active material below the upper limit improves the electronic conductivity of the positive electrode active material layer 112. When a composite material of the positive electrode active material and other materials is used, the average particle size of the composite material is considered the average particle size of the positive electrode active material. "Average particle size" refers to the value (D50) at which the volume-based integrated distribution calculated according to JIS-Z-8819-2 (2001), based on the particle size distribution measured by laser diffraction / scattering on a dilution obtained by diluting particles with a solvent, in accordance with JIS-Z-8825 (2013), becomes 50%. For obtaining particles of the positive electrode active material and the negative electrode active material described later with a predetermined particle size, known methods using, for example, pulverizers and classifiers can be employed.

[0070] The content of the positive electrode active material in the positive electrode active material layer 112 is preferably 50% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, and may also be 80% by mass or more and 95% by mass or less. By setting the content of the positive electrode active material within the above range, it is possible to achieve both high energy density and manufacturability of the positive electrode active material layer 112.

[0071] Conductive agents are typically components made of conductive materials. Even if the volume resistivity of a conductive agent cannot be directly measured, if the volume resistivity is 10 -2Materials whose conductivity is known to be Ω·cm or less are classified as conductive agents. Examples of conductive agents include carbon materials, metals, and conductive ceramics. A carbon material is a material whose main constituent element is carbon. The main constituent element is the element that is present in the largest quantity by mass. For example, the carbon content in a carbon material may be 80% by mass or more, 90% by mass or more, 95% by mass, 99% by mass, or 99.9% by mass or more. It is preferable that the carbon material is a carbon material other than a non-carbonized polymer compound. Examples of carbon materials include graphite, non-graphitic carbon, and graphene-based carbon. Examples of non-graphitic carbon include carbon nanofibers, pitch-based carbon fibers, and carbon black. Examples of carbon black include furnace black, acetylene black, and Ketjen black. Examples of graphene-based carbon include graphene, carbon nanotubes (CNTs), and fullerenes. Conductive agents can take the form of powder or fibers. One or more conductive agents can be used. These materials may be used in combination as conductive agents. For example, a material made by combining carbon black and CNTs may be used.

[0072] The conductive agent content in the positive electrode active material layer 112 is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 9% by mass or less, and even more preferably 3% by mass or more and 8% by mass or less. The upper limit of the conductive agent content may be 5% by mass, 4% by mass, or 3% by mass. By setting the conductive agent content within the above range, it is possible to increase the energy density of the non-aqueous electrolyte energy storage element.

[0073] A fibrillated binder is typically a binder in which the resin has been fibrillated (fibrousized) by shear force. Typically, it refers to a binder in which fine fibers extend from the surface of the main body of the resin, either by branching out or unraveling the fibers. The fibrillation of the binder is confirmed by an SEM (Scanning Electron Microscope) image of the binder. As the resin used as the raw material for the fibrillated binder, fluororesin is preferred, and polytetrafluoroethylene (PTFE) is more preferred. In the positive electrode active material layer 112, it is preferable that the fibrillated binder is uniformly dispersed. Furthermore, it is preferable that the fibrillated binder supports the particulate positive electrode active material. One or more types of fibrillated binders can be used.

[0074] Other binders besides fibrillated binders may include non-fibrillated fluororesins (polytetrafluoroethylene, polyvinylidene fluoride, etc.), polyolefins (polyethylene, polypropylene, etc.), elastomers (ethylene propylene diene rubber, styrene butadiene rubber, fluororubber, etc.), polysaccharide polymers (cellulose, chitosan derivatives, etc.), etc. One or more of these other binders may be used.

[0075] The binder content in the positive electrode active material layer 112 is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 8% by mass or less, even more preferably 1% by mass or more and 5% by mass or less, and still more preferably 1.5% by mass or more and 4% by mass. The upper limit of the binder content may be 5% by mass, 4% by mass, or 3% by mass. By setting the binder content within the above range, the positive electrode active material can be stably maintained.

[0076] The proportion of fibrillated binder to the total binder contained in the positive electrode active material layer 112 is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. Furthermore, it is even more preferable that the binder in the positive electrode active material layer 112 consists substantially of fibrillated binder only.

[0077] The filler is not particularly limited. The filler may be a component other than the positive electrode active material, conductive agent, and binder, and may be a component that is intentionally included. The filler may be included as a component that fills gaps in the positive electrode active material layer 112, or it may be included for other purposes. The filler may be an organic substance such as a polyolefin, or an inorganic substance such as an inorganic oxide, hydroxide, or carbonate. One or more types of fillers may be used. When the positive electrode active material layer 112 contains a filler, the filler content in the positive electrode active material layer 112 can be 0.1% by mass or more and 8% by mass or less, usually preferably 5% by mass or less, and more preferably 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the positive electrode active material layer 112 does not contain a filler.

[0078] The positive electrode active material layer 112 may further contain other components besides the positive electrode active material, conductive agent, fibrillated binder, other binders, and fillers. These other components may include those unintentionally present in the positive electrode active material layer 112. The positive electrode active material layer 112 may also contain impurities unintentionally present as these other components, insofar as they achieve the effects of the present invention. The upper limit of the content of these other components in the positive electrode active material layer 112 may be 10% by mass, 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass. The upper limit of the content of unintentionally present components in the positive electrode active material layer 112 may be 10% by mass, 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass. The upper limit for the amount of impurities unintentionally contained in the positive electrode active material layer 112 may be 10% by mass, or it may be 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass.

[0079] The porosity of the positive electrode active material layer 112 may be, for example, 10% or more and 50% or less. The lower limit of the porosity of the positive electrode active material layer 112 may be 15%, 20% or 30%. The upper limit of the porosity of the positive electrode active material layer 112 may be 45%, 40% or 35%. The "porosity (%)" of the positive electrode active material layer and the negative electrode active material layer described later is calculated by the formula (1 - V2 / V1) × 100, where V1 is the apparent volume (volume including voids) of the positive (negative) electrode active material layer, and V2 is the sum of the solid volumes of the respective materials constituting the positive (negative) electrode active material layer. The sum V2 of the solid volumes of the respective materials constituting the positive (negative) electrode active material layer can be calculated from the content of each material in the positive (negative) electrode active material layer and the true density of each material.

[0080] (Negative electrode active material layer 113) The negative electrode active material layer 113 contains a negative electrode active material and a fibrillated binder. The negative electrode active material layer 113 contains optional components such as a conductive agent, other binders other than the fibrillated binder, and fillers as required. The optional components such as the conductive agent, fibrillated binder, other binders, and fillers can be selected from the materials exemplified for the positive electrode above. The negative electrode active material layer 113 may be formed from a negative electrode mixture containing a negative electrode active material, a fibrillated binder, and other optional components.

[0081] Known negative electrode active materials can be used for the negative electrode active material. For the negative electrode active material of a lithium ion secondary battery, a material that can occlude and release lithium ions is usually used. Examples of the negative electrode active material include metallic lithium; metals or semimetals such as silicon and tin; metal oxides or semimetal oxides such as silicon oxide, titanium oxide, and tin oxide; Li4Ti5O 12 , LiTiO 2、 Titanium-containing oxides such as TiNb2O7; polyphosphoric acid compounds; silicon carbide; carbon materials such as graphite and non-graphitic carbon. Among these materials, carbon materials are preferred, and graphite or non-graphitic carbon is more preferred. The graphite may have its surface coated with other materials such as non-graphitic carbon. One or more negative electrode active materials can be used.

[0082] "Graphite" refers to the average lattice plane spacing (d) of the (002) plane, determined by X-ray diffraction before charging or discharging, or during the discharge state. 002 This refers to carbon materials with a n-scale between 0.33 nm and less than 0.34 nm. Examples of graphite include natural graphite and artificial graphite.

[0083] "Non-graphite carbon" refers to the average lattice plane spacing (d) of the (002) plane, which is determined by X-ray diffraction before charging / discharging or during the discharge state. 002 ) refers to carbon materials with a nautical index of 0.34 nm to 0.42 nm. Non-graphitic carbons include poorly graphitizable carbons and easily graphitizable carbons. "Potentially graphitizable carbon" refers to the above d 002 This refers to carbon materials with a wavelength of 0.36 nm or more and 0.42 nm or less. "Easily graphitizable carbon" refers to the above d 002 This refers to carbon materials with a wavelength of 0.34 nm or more and less than 0.36 nm.

[0084] Here, the "discharge state" of the carbon material refers to a state in which sufficient lithium ions that can be absorbed and released during charging and discharging are released from the carbon material, which is the negative electrode active material. For example, in a half-cell using a negative electrode containing a carbon material as the negative electrode active material as the working electrode and metallic lithium as the counter electrode, this is a state in which the open-circuit voltage is 0.7V or higher.

[0085] The negative electrode active material may be in particulate form. The average particle size of the negative electrode active material can be, for example, 1 nm to 100 μm. If the negative electrode active material is a carbon material, titanium-containing oxide, or polyphosphate compound, its average particle size may be 1 μm to 100 μm. If the negative electrode active material is Si, Sn, Si oxide, or Sn oxide, its average particle size may be 1 nm to 1 μm. Setting the average particle size of the negative electrode active material above the lower limit makes it easier to manufacture or handle the negative electrode active material. Setting the average particle size of the negative electrode active material below the upper limit improves the electronic conductivity of the negative electrode active material layer 113.

[0086] The content of the negative electrode active material in the negative electrode active material layer 113 is preferably, for example, 60% by mass or more and 99% by mass or less, and more preferably 90% by mass or more and 98% by mass or less. By setting the content of the negative electrode active material within the above range, it is possible to achieve both high energy density and manufacturability of the negative electrode active material layer 113.

[0087] When the negative electrode active material is a metal such as metallic lithium, the metallic lithium may exist as pure metallic lithium consisting substantially of the element lithium only, or as a lithium alloy containing other metallic elements. When the negative electrode active material is a metal such as metallic lithium, the lithium element content in the negative electrode active material layer 113 may be 90% by mass or more, 99% by mass or more, or 100% by mass.

[0088] When the negative electrode active material layer 113 contains a conductive agent, the content of the conductive agent in the negative electrode active material layer 113 is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. The content of the conductive agent in the negative electrode active material layer 113 may be 5% by mass or less, or 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the negative electrode active material layer 113 does not contain a conductive agent.

[0089] The binder content in the negative electrode active material layer 113 is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 8% by mass or less. The binder content in the negative electrode active material layer 113 may be 5% by mass or less, or 2% by mass or less.

[0090] The ratio of fibrillated binder to the total binder contained in the negative electrode active material layer 113 is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. Furthermore, it is even more preferable that the binder in the negative electrode active material layer 113 consists substantially only of fibrillated binder.

[0091] The filler in the negative electrode active material layer 113 is a component other than the negative electrode active material, conductive agent, and binder, and may be a component that is intentionally included. The filler may be included as a component that fills gaps in the negative electrode active material layer 113, or it may be included for other purposes. When the negative electrode active material layer 113 contains a filler, the filler content in the negative electrode active material layer 113 can be 0.1% by mass or more and 8% by mass or less, usually preferably 5% by mass or less, and more preferably 2% by mass or less. The technology disclosed herein can also be carried out in a form in which the negative electrode active material layer 113 does not contain a filler.

[0092] The negative electrode active material layer 113 may further contain other components besides the negative electrode active material, conductive agent, fibrillated binder, other binders, and fillers. These other components may include those unintentionally present in the negative electrode active material layer 113. Furthermore, the negative electrode active material layer 113 may contain impurities unintentionally present as these other components, insofar as they achieve the effects of the present invention. The upper limit of the content of these other components in the negative electrode active material layer 113 may be 10% by mass, 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass. The upper limit of the content of unintentionally present components in the negative electrode active material layer 113 may be 10% by mass, 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass. The upper limit for the amount of impurities unintentionally contained in the negative electrode active material layer 113 may be 10% by mass, or it may be 5% by mass, 2% by mass, 1% by mass, 0.1% by mass, or 0.01% by mass.

[0093] The porosity of the negative electrode active material layer 113 may be, for example, 10% or more and 50% or less. The lower limit of the porosity of the negative electrode active material layer 113 may be 15%, 20%, or 30%. The upper limit of the porosity of the negative electrode active material layer 113 may be 45%, 40%, or 35%.

[0094] [Positive electrode 12] The positive electrode 12 comprises a positive electrode substrate 121 and a positive electrode active material layer 122. An intermediate layer may be formed between the positive electrode substrate 121 and the positive electrode active material layer 122. The configurations of the positive electrode substrate 121, the positive electrode active material layer 122, and the intermediate layer can be selected from the configurations exemplified for the positive electrode substrate 111a, positive electrode active material layer 112, and intermediate layer of the bipolar electrode 11.

[0095] [Negative electrode 13] The negative electrode 13 comprises a negative electrode substrate 131 and a negative electrode active material layer 132. An intermediate layer may be formed between the negative electrode substrate 131 and the negative electrode active material layer 132. The configurations of the negative electrode substrate 131, the negative electrode active material layer 132, and the intermediate layer can be selected from the configurations exemplified for the negative electrode substrate 111b, negative electrode active material layer 113, and intermediate layer of the bipolar electrode 11.

[0096] [Separator 14] The separator 14 can be any known separator. For example, the separator 14 can be a separator consisting only of a substrate layer, or a separator in which an inorganic layer containing inorganic particles and a binder is formed on one or both sides of the substrate layer.

[0097] Examples of the base material layer include woven fabric, nonwoven fabric, and porous resin film. Among these forms, porous resin film is preferred from the viewpoint of strength, and nonwoven fabric is preferred from the viewpoint of liquid retention of the non-aqueous electrolyte 15. The material of the base material layer is not particularly limited as long as it has insulating properties, but resins such as polyolefins (polyethylene, polypropylene, etc.), polyimide, and aramid are preferred.

[0098] Examples of inorganic compounds that constitute the inorganic particles used in the inorganic layer include oxides such as iron oxide, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, calcium oxide, and magnesium oxide; nitrides such as aluminum nitride and silicon nitride; carbonates such as calcium carbonate; sulfates such as barium sulfate; sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium titanate; covalent crystals such as silicon; mineral resource-derived materials such as talc, zeolite, kaolin, bentonite, and mica, or their artificial counterparts. One or more types of inorganic particles can be used. The average particle size of the inorganic particles is preferably, for example, 0.5 μm to 10 μm. The inorganic particle content in the inorganic layer is preferably 50% to 99% by mass, and more preferably 80% to 98% by mass.

[0099] Examples of binders used in the inorganic layer include those similar to those exemplified in the positive electrode active material layer.

[0100] As described above, the separator 14 preferably has a resin layer located on its outermost surface from the viewpoint of improving manufacturing efficiency. Furthermore, it is more preferable that both sides of the separator 14 are formed by resin layers. "Resin layer" refers to a layer having a resin content of 50% by mass or more.

[0101] The separator 14 having a resin layer located on the outermost surface can be configured such that a base layer, which serves as the resin layer, is exposed on at least one of its outermost surfaces. The separator 14 can be configured such that one side is formed by a resin layer and it has a base layer, which serves as the resin layer, and an inorganic layer laminated on one side of the base layer. The separator 14 can be configured such that both sides are formed by resin layers and it consists only of a base layer, which serves as the resin layer. The resin contained in the resin layer can be the same as the resin exemplified as the material for the base layer.

[0102] The lower limit of the resin content in the resin layer is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and even more preferably 80% by mass. On the other hand, the upper limit of the resin content can be, for example, 95% by mass, and the resin layer may consist substantially of only resin. Note that if two or more types of resin are used in mixture, the resin content refers to the total resin content.

[0103] The porosity of the separator 14 may be, for example, 20% or more and 80% or less. The lower limit of the porosity of the separator 14 may be 30%, 40%, or 50% from the viewpoint of discharge performance, etc. The upper limit of the porosity of the separator 14 may be 70%, 60%, or 50% from the viewpoint of strength, etc. In this specification, "porosity" is a volume-based value and means a measurement value obtained with a mercury porosimeter.

[0104] The average thickness of the separator 14 may be, for example, 5 μm or more and 40 μm or less, preferably 8 μm or more and 30 μm or less, and more preferably 10 μm or more and 20 μm or less.

[0105] [Nonaqueous electrolyte 15] A known non-aqueous electrolyte 15 can be used. The non-aqueous electrolyte 15 is a medium that is responsible for transporting charge transport ions (e.g., lithium ions) between the positive electrode and the negative electrode, and is substantially free of water.

[0106] The non-aqueous electrolyte 15 comprises a non-aqueous solvent and an electrolyte salt dissolved in this non-aqueous solvent.

[0107] Any known non-aqueous solvent can be used. Examples of non-aqueous solvents include carbonates, esters, ethers, amides, and nitriles. Examples of carbonates include cyclic carbonates and linear carbonates. Examples of esters include carboxylic acid esters, phosphate esters, and sulfonic acid esters. As non-aqueous solvents, compounds in which some of the hydrogen atoms contained in these compounds are substituted with halogen atoms may also be used. One or more non-aqueous solvents can be used.

[0108] A cyclic carbonate refers to a carbonate having a ring structure containing a carbonate group (-OC(=O)-O-). Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, vinylethylene carbonate, chloroethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, styrene carbonate, 1-phenylvinylene carbonate, and 1,2-diphenylvinylene carbonate. A cyclic carbonate may be a saturated cyclic carbonate such as ethylene carbonate, or an unsaturated cyclic carbonate such as vinylene carbonate. "Saturated" means not having carbon-carbon unsaturated bonds (carbon-carbon double bonds and carbon-carbon triple bonds). "Unsaturated" means having carbon-carbon unsaturated bonds. As a cyclic carbonate, a saturated cyclic carbonate is preferred, and ethylene carbonate is more preferred.

[0109] A chain-like carbonate refers to a carbonate that does not have a ring structure containing a carbonate group. Examples of chain-like carbonates include diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, diphenyl carbonate, trifluoroethyl methyl carbonate, and bis(trifluoroethyl) carbonate. The chain-like carbonate may be a saturated chain-like carbonate such as dimethyl carbonate, or an unsaturated chain-like carbonate such as diphenyl carbonate. A saturated chain-like carbonate is preferred as the chain-like carbonate, and ethyl methyl carbonate is more preferred.

[0110] The non-aqueous solvent preferably contains carbonate, and more preferably contains both cyclic carbonate and linear carbonate. The carbonate content in the non-aqueous solvent is preferably 80% to 100% by volume, may be 99% to 100% by volume, or 100% by volume. Using cyclic carbonate can promote the dissociation of the electrolyte salt and increase the ionic conductivity of the non-aqueous electrolyte 15. Using linear carbonate can keep the viscosity of the non-aqueous electrolyte 15 low. When using both cyclic carbonate and linear carbonate, the volume ratio of cyclic carbonate to linear carbonate (cyclic carbonate:linear carbonate) is preferably in the range of 5:95 to 50:50.

[0111] Any known electrolyte salt can be used. Examples of electrolyte salts include lithium salts, sodium salts, potassium salts, magnesium salts, and onium salts. Among these, lithium salts are preferred. One or more electrolyte salts can be used.

[0112] Examples of lithium salts include inorganic lithium salts such as LiPF6, LiPO2F2, LiBF4, and LiClO4; imide salts such as LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, and LiN(SO2CF3)(SO2C4F9); and lithium oxalate salts such as LiB(C2O4)2, LiBF2(C2O4), and LiPF2(C2O4)2. LiN(SO2F)2 is also an inorganic lithium salt. Among these, inorganic lithium salts are preferred, and LiPF6 is more preferred. Imide salts are also sometimes preferred.

[0113] The electrolyte salt content in non-aqueous electrolyte solution 15 is 0.1 mol / dm³ at 20°C and 1 atm. 3 More than 2.5mol / dm 3 The following is preferred: 0.3 mol / dm 3 More than 2.0mol / dm 3 The following is more preferable: 0.5 mol / dm3 More than 1.7mol / dm 3 The following is even more preferable: 0.7 mol / dm 3 More than 1.5mol / dm 3 The following is particularly preferable. By setting the electrolyte salt content within the above range, the ionic conductivity of the non-aqueous electrolyte 15 can be increased.

[0114] The non-aqueous electrolyte 15 may contain additives in addition to the non-aqueous solvent and electrolyte salt. One or more types of additives may be used. When additives are used in the non-aqueous electrolyte 15, the additive content in the non-aqueous electrolyte 15 is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 7% by mass or less, even more preferably 0.2% by mass or more and 5% by mass or less, and particularly preferably 0.3% by mass or more and 3% by mass or less.

[0115] [Container 16] The container 16 contains multiple bipolar electrodes 11, a positive electrode 12, a negative electrode 13, multiple separators 14, and a non-aqueous electrolyte 15. The container 16 can be made of metal materials such as aluminum or stainless steel, or resin materials, with metal materials being preferred from the viewpoint of strength and other factors. Composite materials of metal and resin materials can also be used. The container 16 may have multiple pouring ports.

[0116] As described above, the internal space of the container 16 is formed in a rectangular shape when viewed in the stacking direction. Aside from the internal space, the shape of the container 16 is not particularly limited.

[0117] [Shape, application, etc. of the non-aqueous electrolyte energy storage element 10] The shape of the non-aqueous electrolyte energy storage element 10 according to one embodiment of the present invention is not particularly limited. The non-aqueous electrolyte energy storage element 10 may be, for example, a prismatic battery.

[0118] The applications of the non-aqueous electrolyte energy storage element 10 according to one embodiment of the present invention are not particularly limited. The non-aqueous electrolyte energy storage element 10 can be used, for example, as a power source for automobiles such as electric vehicles, hybrid vehicles, and plug-in hybrid vehicles, as a power source for electronic devices such as personal computers and communication terminals, and as a power storage power source.

[0119] The non-aqueous electrolyte energy storage element 10 of the present invention can be used individually or in combination. The non-aqueous electrolyte energy storage element may be used individually when the required output and voltage are small. On the other hand, when at least one of the required output and voltage is large, the non-aqueous electrolyte energy storage element 10 may be used as an energy storage device in combination with other non-aqueous electrolyte energy storage elements. In an energy storage device in which multiple non-aqueous electrolyte energy storage elements are combined, at least one of the non-aqueous electrolyte energy storage elements included in the energy storage device may be the non-aqueous electrolyte energy storage element 10 according to one embodiment of the present invention. The energy storage device will be described in detail later.

[0120] The non-aqueous electrolyte energy storage element 10 according to one embodiment of the present invention may be restrained in such a way as to maintain a constant thickness of the container, or it may not be restrained in such a way. Alternatively, it may be restrained in such a way as to apply a constant load to the container. When the container is restrained, expansion of the container due to charge-discharge cycles, etc., may be suppressed, and a decrease in charge-discharge performance may be suppressed. When the container is restrained, a load may or may not be applied to the electrode body inside the container. Furthermore, the non-aqueous electrolyte energy storage element 10 may be restrained in the stacking direction so that the bipolar electrodes 11 are in close contact with each other. In addition, the non-aqueous electrolyte energy storage element 10 may be restrained so that the bipolar electrodes 11 are pressed in the stacking direction. By restraining the non-aqueous electrolyte energy storage element 10 in the stacking direction, the movement of the separator is suppressed, which in turn improves the quality of the non-aqueous electrolyte energy storage element 10 while easily increasing manufacturing efficiency. For example, the non-aqueous electrolyte energy storage element 10 or the energy storage device may be provided with a restraining member that performs such restraint.

[0121] [Manufacturing method for non-aqueous electrolyte energy storage elements] A method for manufacturing a non-aqueous electrolyte energy storage element according to one embodiment of the present invention comprises manufacturing an electrode (bipolar electrode) having a substrate, a positive electrode active material layer laminated on one side of the substrate, and a negative electrode active material layer laminated on the other side of the substrate, wherein at least one of the positive electrode active material layer and the negative electrode active material layer contains a fibrillation binder. This method for manufacturing a non-aqueous electrolyte energy storage element can provide a non-aqueous electrolyte energy storage element equipped with a bipolar electrode and with high manufacturing efficiency. Each component of the non-aqueous electrolyte energy storage element manufactured by this method is the same as each component of the non-aqueous electrolyte energy storage element 10 described above.

[0122] The method for manufacturing the non-aqueous electrolyte energy storage element may include, in addition to manufacturing a bipolar electrode, manufacturing a positive electrode and a negative electrode that are arranged to sandwich a laminate of stacked bipolar electrodes, stacking the bipolar electrode, positive electrode, negative electrode and separator, housing the bipolar electrode and the like in a container, and injecting a non-aqueous electrolyte.

[0123] The fabrication of a bipolar electrode may include fabricating an independent positive electrode mixture layer and an independent negative electrode mixture layer containing a fibrillated binder, laminating the independent positive electrode mixture layer and the independent negative electrode mixture layer onto a substrate, pressing the independent positive electrode mixture layer and the independent negative electrode mixture layer onto the substrate to form a positive electrode active material layer and a negative electrode active material layer, forming a thinned layer region at the outer edge of the positive electrode active material layer, and cutting the substrate, positive electrode active material layer and negative electrode active material layer into appropriate shapes and sizes. When fabricating a bipolar electrode, it is preferable to fabricate the independent positive electrode mixture layer and the independent negative electrode mixture layer without using solvents, and to form the positive electrode active material layer and the negative electrode active material layer without using solvents. That is, it is preferable to form the positive electrode active material layer and the negative electrode active material layer by dry coating. Note that "independent positive electrode mixture layer" and "independent negative electrode mixture layer" refer to sheet-like positive electrode mixture layer and negative electrode mixture layer fabricated independently from the substrate. Since the independent positive electrode mixture layer and the independent negative electrode mixture layer contain a fibrillation binder, the positive electrode active material layer and the negative electrode active material layer can be easily formed by dry coating without the use of solvents.

[0124] The independent positive electrode mixture layer and the independent negative electrode mixture layer may be prepared by mixing a positive electrode active material or a negative electrode active material, a fibrillated binder, and any other component, and then rolling this mixture (composite) into a sheet. The prepared independent positive electrode mixture layer and independent negative electrode mixture layer may be in the form of, for example, a strip.

[0125] In laminating the independent positive electrode mixture layer and the independent negative electrode mixture layer onto a substrate, it is preferable to laminate the independent positive electrode mixture layer and the independent negative electrode mixture layer onto the substrate simultaneously. Furthermore, in forming the positive electrode active material layer and the independent negative electrode active material layer, it is preferable to press the independent positive electrode mixture layer and the independent negative electrode mixture layer onto the substrate simultaneously. Figure 3 shows an example of these processes. In Figure 3, the independent positive electrode mixture layer 17 and the independent negative electrode mixture layer 18 are simultaneously extruded and laminated onto the substrate 111 by a feed roller R1, and then the independent positive electrode mixture layer 17 and the independent negative electrode mixture layer 18 are simultaneously pressed onto both sides of the substrate 111 by two press rollers R2. In this case, the positive electrode active material layer 112 and the negative electrode active material layer 113 are simultaneously laminated onto the substrate 111. By laminating the positive electrode active material layer and the negative electrode active material layer onto the substrate simultaneously in this way, manufacturing efficiency can be increased.

[0126] Forming a thinned region at the outer edge of the positive electrode active material layer may be done by scraping off a portion of the outer edge of the positive electrode active material layer, or by pressing the outer edge of the positive electrode active material layer. One method of forming a thinned region by pressing the outer edge of the positive electrode active material layer is to roll the outer edge by pressing the positive electrode active material layer, and then cut off the portion of the outer edge of the positive electrode active material layer that extends beyond the outer edge of the substrate. Forming the thinned region may be done simultaneously with forming the positive electrode active material layer and the negative electrode active material layer by pressing the independent positive electrode mixture layer and the independent negative electrode mixture layer onto the substrate.

[0127] Placing bipolar electrodes or the like in a container may include adhering the inner wall of the container to the substrate of the bipolar electrodes in order to seal the non-aqueous electrolyte in a later step.

[0128] Injecting a non-aqueous electrolyte may include injecting the non-aqueous electrolyte into the spaces between bipolar electrodes, between bipolar electrodes and the positive electrode, and between bipolar electrodes and the negative electrode through a plurality of corresponding injection ports provided in the container, and sealing the injection ports.

[0129] [Energy storage device] The energy storage device 30 in Figure 4 comprises a plurality of energy storage units 20. Each energy storage unit 20 comprises a plurality of electrically connected non-aqueous electrolyte energy storage elements 10. The energy storage device 30 may also include busbars (not shown) for electrically connecting the plurality of non-aqueous electrolyte energy storage elements 10, busbars (not shown) for electrically connecting the plurality of energy storage units 20, etc. The energy storage unit 20 or the energy storage device 30 may also include a condition monitoring device (not shown) for monitoring the state of one or more non-aqueous electrolyte energy storage elements 10.

[0130] [Other embodiments] The non-aqueous electrolyte energy storage element 10 of the present invention is not limited to the above embodiments, and various modifications may be made without departing from the spirit of the present invention. For example, some of the components of the above embodiments can be replaced with well-known technologies. Also, some of the components of the above embodiments can be deleted. Furthermore, well-known technologies can be added to the components of the above embodiments.

[0131] In the above embodiment, a case in which a non-aqueous electrolyte energy storage element is used as a rechargeable non-aqueous electrolyte secondary battery was described, but the type, shape, dimensions, capacity, etc. of the non-aqueous electrolyte energy storage element are arbitrary. The present invention can also be applied to various secondary batteries, electric double-layer capacitors, lithium-ion capacitors, and other capacitors.

[0132] In the above embodiment, a case in which a separator is interposed between bipolar electrodes was described, but the non-aqueous electrolyte energy storage element of the present invention does not need to have a separator. For example, the bipolar electrodes may be in direct contact with each other with a non-conductive layer formed on the active material layer of the positive or negative electrode. Thus, the bipolar electrodes may further have layers other than the substrate, intermediate layer, and active material layer.

[0133] In the above embodiment, a case in which the non-aqueous electrolyte energy storage element has multiple bipolar electrodes was described, but the non-aqueous electrolyte energy storage element may also have a configuration in which it has one bipolar electrode.

[0134] In the above embodiment, a case was described in which the substrate of the bipolar electrode is constructed by laminating a positive electrode substrate and a negative electrode substrate. However, the substrate of the bipolar electrode may consist of only one type of substrate (a single layer substrate) selected from the materials exemplified as the positive electrode substrate or the negative electrode substrate. For example, when the negative electrode active material is lithium titanate, the substrate of the bipolar electrode may be a single layer substrate made of aluminum.

[0135] In the above embodiment, the case in which both the positive electrode active material and the negative electrode active material of the bipolar electrode contain a fibrillation binder was described, but it is also possible for either the positive electrode active material or the negative electrode active material of the bipolar electrode to contain a fibrillation binder.

[0136] In the above embodiment, the case in which the internal space of the bipolar electrodes and container is rectangular when viewed in the stacking direction was described, but the configuration of the present invention is not limited to this. These shapes when viewed in the stacking direction may be circular or any other shape that can seal the electrolyte injected between the bipolar electrodes.

[0137] In the above embodiment, the case in which the positive electrode active material layer of the bipolar electrode has a thinned-layer region was described, but the positive electrode active material layer may also be configured not to have a thinned-layer region. For example, the area of ​​the positive electrode active material layer of the bipolar electrode may be made smaller than the area of ​​the negative electrode active material layer to suppress the non-uniform deposition of charge transport ions as metal.

[0138] In the above embodiment, the case in which the positive electrode active material layer or the negative electrode active material layer of the bipolar electrode is in close contact with the separator was described, but the positive electrode active material layer or the negative electrode active material layer may be arranged with a gap between them and the separator in the stacking direction.

[0139] This invention can be applied to non-aqueous electrolyte energy storage elements used as power sources for electronic devices such as personal computers and communication terminals, as well as automobiles. [Explanation of symbols]

[0140] 10 Non-aqueous electrolyte energy storage element 11 electrodes 111 Base material 111a Positive electrode base material 111b Negative electrode base material 112 Cathode active material layer 112a Thinning area 113 Negative electrode active material layer 12 Positive electrode 121 Positive electrode substrate 122 Cathode active material layer 13 Negative electrode 131 Negative electrode substrate 132 Negative electrode active material layer 14 Separator 15 Nonaqueous electrolyte 16 Container 17. Independent cathode mixture layer 18. Independent negative electrode mixture layer R1 Feed Roller R2 Press Roller 20 Energy storage units 30 Energy storage devices

Claims

1. The electrode comprises a base material, a positive electrode active material layer laminated on one side of the base material, and a negative electrode active material layer laminated on the other side of the base material. A non-aqueous electrolyte energy storage element in which at least one of the positive electrode active material layer and the negative electrode active material layer includes a fibrillated binder.

2. The above positive electrode active material layer contains a fibrillated binder, The non-aqueous electrolyte energy storage element according to claim 1, wherein the average thickness of one positive electrode active material layer is 100 μm or more.

3. The above negative electrode active material layer contains a fibrillated binder, The non-aqueous electrolyte energy storage element according to claim 1 or claim 2, wherein the average thickness of one negative electrode active material layer is 100 μm or more.

4. The non-aqueous electrolyte energy storage element according to claim 1 or claim 2, wherein the positive electrode active material layer has a thinned layer region at its outer edge when viewed in the stacking direction, with an average thickness smaller than that of the central portion.

5. The system comprises at least two adjacent electrodes and a separator having a resin layer located on the outermost surface. The separator is positioned between the first positive electrode active material layer of the first electrode and the second negative electrode active material layer of the second electrode facing the first positive electrode active material layer. The non-aqueous electrolyte energy storage element according to claim 1 or claim 2, wherein the resin layer of the separator and the first positive electrode active material layer and the second negative electrode active material layer containing the fibrillated binder are in close contact.

6. The non-aqueous electrolyte energy storage element according to claim 5, wherein the adjacent electrodes are pressed in the stacking direction.

7. The invention comprises manufacturing an electrode having a substrate, a positive electrode active material layer laminated on one side of the substrate, and a negative electrode active material layer laminated on the other side of the substrate. A method for manufacturing a non-aqueous electrolyte energy storage element, wherein at least one of the positive electrode active material layer and the negative electrode active material layer includes a fibrillated binder.

8. A method for manufacturing a non-aqueous electrolyte energy storage element according to claim 7, wherein the production of the above electrodes includes simultaneously laminating the above positive electrode active material layer and the above negative electrode active material layer onto the above substrate.

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