Honeycomb type lithium ion battery and method for manufacturing the same

Abstract

The present invention provides a honeycomb lithium ion battery capable of suppressing direct current resistance and a method for manufacturing the same. The honeycomb lithium ion battery is a honeycomb lithium ion battery having a negative electrode, a positive electrode and a separator layer, characterized in that the negative electrode has a plurality of through holes extending in a single direction, the separator layer has Li ion permeability and is at least arranged on the inner wall of the through hole to physically isolate the negative electrode from the positive electrode, the positive electrode is arranged inside the through hole at least via the separator layer, and the positive electrode contains a rod-shaped conductive additive, which is oriented in the through direction of the through hole.

Description

Technical Field

[0001] The present application relates to a honeycomb lithium ion battery and a method for manufacturing the same. Background Art

[0002] Patent document 1 discloses a honeycomb structure collector for lithium ion secondary battery electrodes having a titanium nitride film adhered to the partition surface of a cell on the outer surface of a carbonaceous honeycomb structure, and a lithium ion secondary battery electrode having a positive or negative electrode active material filled in the cell of the collector.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-126736 Summary of the invention

[0006] When using an electrode with a honeycomb structure as disclosed in Patent Document 1, as a battery shape, the longer the hole penetration direction is, the more advantageous it is for designing a battery with excellent energy density. However, in this case, compared with the case of using a general flat electrode, the distance from the electrode layer to the collector terminal (or collector part) becomes longer, and therefore, a significant increase in DC resistance caused by the high resistivity of the positive electrode composite material becomes a problem.

[0007] Therefore, in view of the above-mentioned actual situation, an object of the present disclosure is to provide a honeycomb type lithium ion battery capable of suppressing DC resistance and a method for manufacturing the same.

[0008] As a solution to the above-mentioned problems, the present invention provides a honeycomb lithium-ion battery, which is a honeycomb lithium-ion battery having a negative electrode, a positive electrode and a separator layer, characterized in that the negative electrode has a plurality of through holes extending in a single direction; the separator layer has Li ion permeability and is at least arranged on the inner wall of the through hole to physically isolate the negative electrode from the positive electrode; the positive electrode is arranged inside the through hole at least via the separator layer; the positive electrode contains a rod-shaped conductive aid; and the rod-shaped conductive aid is oriented in the through direction of the through hole.

[0009] In the honeycomb lithium ion battery, the content of the rod-shaped conductive agent in the positive electrode may be 2% by weight or more. Also, the length of the rod-shaped conductive agent may be 30 μm or more.

[0010] In addition, as a solution to the above-mentioned problems, the present disclosure provides a method for manufacturing a honeycomb lithium ion battery, which is a method for manufacturing a honeycomb lithium ion battery having a negative electrode, a positive electrode and a separator layer, and is characterized in that it comprises: a process of making a negative electrode having a plurality of through holes extending in a single direction, a process of disposing a separator layer at least on the inner wall of the through hole, and a process of disposing a positive electrode inside the through hole at least via the separator layer; the separator layer has Li ion permeability and physically isolates the negative electrode from the positive electrode, the positive electrode contains a rod-shaped conductive aid, and in the process of disposing the positive electrode, the paste-like positive electrode material constituting the positive electrode is pressed into the through hole of the negative electrode disposed with the separator layer, thereby oriented in the through direction of the through hole.

[0011] According to the honeycomb lithium-ion battery disclosed in the present invention, the positive electrode disposed inside the through hole of the negative electrode of the honeycomb structure contains a rod-shaped conductive aid, and the rod-shaped conductive aid is oriented in the through direction of the through hole. As a result, it is easy to form a current path in the positive electrode, and the DC resistance can be suppressed. In addition, according to the manufacturing method of the honeycomb lithium-ion battery disclosed in the present invention, a honeycomb lithium-ion battery with suppressed DC resistance can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a perspective view of the negative electrode 10 .

[0013] Figure 2 1 is a schematic cross-sectional view of a honeycomb type lithium ion battery 100 .

[0014] Figure 3 is a flow chart of a method 1000 for manufacturing a honeycomb lithium-ion battery.

[0015] Figure 4 This is a cross-sectional image of the battery of Example 1.

[0016] Explanation of symbols

[0017] 10 Negative electrode

[0018] 20 Positive electrode

[0019] 21 Rod-shaped conductive additive

[0020] 30 Spacer layer

[0021] 40 Negative electrode collector

[0022] 50 Positive electrode collector

[0023] 100 Honeycomb Li-ion Battery DETAILED DESCRIPTION

[0024] [Honeycomb type lithium-ion battery]

[0025] The honeycomb type lithium ion battery of the present disclosure will be described with reference to a honeycomb type lithium ion battery 100 (hereinafter, sometimes referred to as “battery 100 ”) as one embodiment. Figure 1 A perspective view of the negative electrode 10 is shown in FIG. Figure 2 A schematic cross-sectional view of the battery 100 along the penetration direction of the through hole 11 of the negative electrode 10 is shown.

[0026] like Figure 2 As shown, the battery 100 includes a negative electrode 10, a positive electrode 20, and a separator layer 30. In addition, the battery 100 may include a negative electrode current collector 40 and a positive electrode current collector 50.

[0027] <Negative electrode 10>

[0028] The negative electrode 10 has a plurality of through holes 11 extending in one direction (through direction). Such a structure is called a so-called honeycomb structure. The overall shape of the negative electrode 10 is not particularly limited and may be as follows: Figure 1 The shape is a quadrangular prism, but other prisms or a circular column may be used. The size of the entire negative electrode 10 is not particularly limited and may be appropriately set according to the purpose.

[0029] The shape of the through hole 11 provided in the negative electrode 10 is not particularly limited. For example, the cross section in the direction perpendicular to the through direction may be circular, or may be a polygon such as a quadrilateral. The aperture of the through hole 11 is not particularly limited as long as the positive electrode 20 and the separator layer 30 can be arranged inside the through hole 11. For example, it is in the range of 10 μm to 1000 μm. The aperture diameter may be, for example, the Fred diameter. In addition, the spacing (rib thickness) between adjacent through holes 11 is not particularly limited as long as it has a strength capable of maintaining the through hole 11. For example, it is in the range of 10 μm to 1000 μm. The through holes 11 can be randomly arranged in the negative electrode 10, but from the viewpoint of ensuring the filling amount of the positive electrode 20 and increasing the capacity, it is preferably as follows. Figure 1 As shown, they are arranged regularly.

[0030] The negative electrode 10 includes a negative electrode active material. Examples of the negative electrode active material include carbon-based negative electrode active materials such as graphite, graphitizable carbon, and non-graphitizable carbon, and alloy-based negative electrode active materials containing silicon (Si), tin (Sn), and the like. The average particle size of the negative electrode active material is, for example, in the range of 5 to 50 μm. The content of the negative electrode active material in the negative electrode 10 is, for example, in the range of 50 wt % to 99 wt %.

[0031] Here, in this specification, the "average particle size" is a particle size (median particle size) at a cumulative value of 50% in a volume-based particle size distribution measured by a laser diffraction / scattering method.

[0032] The negative electrode 10 may contain a binder arbitrarily. Examples of the binder include carboxymethyl cellulose; rubber-based binders such as butadiene rubber, hydrogenated butadiene rubber, styrene butadiene rubber (SBR), hydrogenated styrene butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, and ethylene propylene rubber; fluoride-based binders such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVDF-HFP), polytetrafluoroethylene, and fluororubber; polyolefin-based thermoplastic resins such as polyethylene, polypropylene, and polystyrene; imide-based resins such as polyimide and polyamide-imide; amide-based resins such as polyamide; acrylic resins such as polymethyl acrylate and polyethyl acrylate; methacrylic resins such as polymethyl methacrylate and polyethyl methacrylate. The content of the binder in the negative electrode 10 is, for example, in the range of 1% to 10% by weight.

[0033] The negative electrode 10 may arbitrarily contain a conductive aid. Examples of conductive materials include carbon materials and metal materials. Examples of carbon materials include acetylene black (AB), ketjen black (KB) and other particulate carbon materials, carbon fibers such as VGCF, carbon nanotubes (CNT), carbon nanofibers (CNF) and other fibrous carbon materials. Examples of metal materials include Ni, Cu, Fe, and SUS. The metal material is preferably in a particulate or fibrous form. The content of the conductive aid in the negative electrode 10 is, for example, in the range of 1% to 10% by weight.

[0034] <Positive electrode 20>

[0035] The positive electrode 20 is disposed inside the through hole 11 via at least the separator layer 30. Hereinafter, the positive electrode 20 disposed inside the through hole 11 may be referred to as an internal positive electrode.

[0036] In addition, the positive electrode 20 may be disposed on at least one surface in the through-direction of the battery 100 (the surface on the inner side of the positive electrode collector 50 when the positive electrode collector 50 is disposed). Hereinafter, the positive electrode 20 disposed on the surface of the battery 100 may be referred to as a surface positive electrode. The surface positive electrode is disposed so as to be connected to the positive electrode collector 50. Figure 2 In the embodiment, the positive electrode 20 is disposed entirely from the inside of the through hole 11 to both surfaces in the through direction of the battery 100. The thickness of the surface positive electrode is not particularly limited, and is, for example, in the range of 10 μm to 1000 μm.

[0037] The positive electrode 20 includes a positive electrode active material and a rod-shaped conductive aid 21. Examples of the positive electrode active material include lithium cobalt oxide, lithium cobalt nickel manganese oxide, olivine-type metal oxides, and spinel-type lithium manganese oxide. The average particle size of the positive electrode active material is, for example, in the range of 5 to 100 μm. The content of the positive electrode active material in the positive electrode 20 is, for example, in the range of 50 wt % to 99 wt %.

[0038] Examples of the rod-shaped conductive aid 21 include fibrous carbon materials such as ground fibers. The content of the rod-shaped conductive aid 21 in the positive electrode 20 is not particularly limited, and even a small amount thereof can suppress the DC resistance as long as it is contained in the positive electrode 20. The content of the rod-shaped conductive aid 21 in the positive electrode 20 is preferably 1% by weight or more, more preferably 2% by weight or more. In addition, from the perspective of balance with the battery energy density, the content of the rod-shaped conductive aid 21 in the positive electrode 20 is preferably 30% or less, more preferably 6% or less by weight.

[0039] The longer the length of the rod-shaped conductive aid 21, the more effective it is in reducing the DC resistance. However, if the length of the rod-shaped conductive aid is longer than the shortest length of the aperture of the through hole 11, clogging may occur when the paste-like positive electrode material constituting the positive electrode 20 is pressed into the through hole 11. For example, in the case where the shape of the through hole 11 is circular, the shortest length in the aperture of the through hole 11 refers to the length of the diameter, in the case of a rectangle, it refers to the length of the short side, and in the case of a hexagon, it refers to the shortest length of the line connecting the two opposing sides at right angles. Specifically, the length of the rod-shaped conductive aid 21 is preferably 10 μm or more, more preferably 20 μm or more, and further preferably 30 μm or more. The length of the rod-shaped conductive aid 21 is preferably 1000 μm or less, more preferably 500 μm or less, and further preferably 300 μm or less. Here, the length of the rod-shaped conductive aid 21 refers to the average length, for example, the average value of the lengths of any 30 rod-shaped conductive aids 21 observed by an optical microscope.

[0040] Here, as shown in FIG. 2 , the rod-shaped conductive aid 21 is oriented in the through-hole 11's through-hole direction. "The rod-shaped conductive aid 21 is oriented in the through-hole 11's through-hole direction" means that the ratio of the rod-shaped conductive aid 21 that is inclined within ±20° relative to the through-hole direction in the through-hole cross section of the battery 100 is 70% or more. The orientation of the rod-shaped conductive aid 21 can be confirmed by cutting the battery 100 in the through-hole direction and observing the cross section using an optical microscope. The number of rod-shaped conductive aids 21 observed is at least 30.

[0041] In this way, the positive electrode 20 includes the rod-shaped conductive additive 21, and the rod-shaped conductive additive 21 is oriented in the penetrating direction. This can ensure a sufficient current path in the positive electrode 20, and can suppress the DC resistance.

[0042] The positive electrode 20 may optionally contain a binder. The type and content of the binder that can be used for the positive electrode 20 are the same as those described for the negative electrode 10 .

[0043] The positive electrode 20 may arbitrarily contain a conductive agent other than the rod-shaped conductive agent 21. As conductive agents other than the rod-shaped conductive agent 21, for example, acetylene black (AB), Ketjen black (KB) and other particulate carbon materials can be cited. The content of the particulate carbon material in the positive electrode 20 is, for example, in the range of 1 wt% to 10 wt%.

[0044] Compared with rod-shaped conductive additives, particulate conductive additives are difficult to form long-distance current paths. Therefore, if a particulate conductive additive is used alone, the effect of reducing DC resistance is small. On the other hand, particulate conductive additives are beneficial to the formation of a reaction field near the surface of the positive electrode active material, and the effect of reducing the reaction resistance is high. Therefore, in order to reduce the resistance of the entire battery, it is preferred to use a rod-shaped conductive additive and a particulate conductive additive in combination.

[0045] <Separator layer 30>

[0046] The separator layer 30 has Li ion permeability and is disposed at least on the inner wall of the through hole 11 to physically separate the negative electrode 10 from the positive electrode 20. In other words, the separator layer 30 is disposed between the negative electrode 10 and the positive electrode 20 inside the through hole 11. Hereinafter, the separator layer 30 disposed inside the through hole 11 is sometimes referred to as a partition wall separator layer. The thickness of the partition wall separator layer is not particularly limited, and is, for example, in the range of 10 μm to 1000 μm.

[0047] In addition, if Figure 2 As shown, in order to connect the positive electrode collector 50 to the positive electrode 20, the positive electrode 20 (surface positive electrode) is sometimes arranged on the surface of the through-direction of the battery 100. In such a case, the negative electrode 10 and the positive electrode 20 (surface positive electrode) need to be physically isolated. Therefore, the separator layer 30 can be arranged between the negative electrode 10 and the positive electrode 20 on the surface of the through-direction of the battery 100. Hereinafter, the separator layer 30 arranged on the surface is sometimes referred to as an insulating film separator layer. The thickness of the insulating film separator layer is not particularly limited, for example, in the range of 10μm to 1000μm.

[0048] When the battery 100 is in the form of using an electrolyte, the separator layer 30 needs to be a porous film from the viewpoint of ensuring ion permeability. For example, a particle film or a porous resin composed of inorganic particles such as boehmite and a binder can be used. In the former case, the average particle size of the inorganic particles is, for example, in the range of 10nm to 50μm, and the content of the inorganic particles in the separator 30 is preferably 20% by weight to 99% by weight. In addition, a fully solid battery that does not use an electrolyte can also adopt this structure, in which case the separator itself can be used as a solid electrolyte.

[0049] The type, content, etc. of the binder that may be included in the separator layer 30 are the same as those described for the negative electrode 10 .

[0050] When the battery 100 is in the form of using an electrolyte, the electrolyte is injected into the entire interior of the electrode body (specifically, all the holes in the negative electrode 10, the positive electrode 20, and the separator layer 30). As the electrolyte, a non-aqueous electrolyte containing a lithium salt as a main component is preferred. Examples of non-aqueous electrolytes include ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and the like. They can be used alone or in combination. In addition, examples of lithium salts include LiPF6, LiBF4, and the like. The concentration of the lithium salt in the electrolyte can be, for example, 0.005 mol / L to 0.5 mol / L.

[0051] <Negative Electrode Collector 40>

[0052] The battery 100 may include a negative electrode current collector 40. The negative electrode current collector 40 is disposed, for example, on the side surface of the negative electrode 10. Examples of the material of the negative electrode current collector 40 include SUS, Cu, Al, Ni, Fe, Ti, Co, and Zn.

[0053] <Positive electrode current collector 50>

[0054] The battery 100 may include a positive electrode current collector 50 . The positive electrode current collector 50 is disposed on the positive electrode 20 . Figure 2 In the embodiment, the positive electrode collector 50 is connected to the surface positive electrodes arranged on both surfaces in the through-going direction of the battery 100. Examples of the material of the positive electrode collector 50 include SUS, Cu, Al, Ni, Fe, Ti, Co, and Zn.

[0055] The honeycomb lithium ion battery of the present disclosure has been described above using the honeycomb lithium ion battery 100 as an embodiment. According to the honeycomb lithium ion battery of the present disclosure, the positive electrode arranged inside the through hole of the negative electrode of the honeycomb structure contains a rod-shaped conductive auxiliary agent, and the rod-shaped conductive auxiliary agent is oriented in the through direction of the through hole. As a result, it is easy to form a current path in the positive electrode, and the DC resistance can be suppressed.

[0056] [Method for manufacturing honeycomb type lithium ion battery]

[0057] Next, a method for manufacturing a honeycomb type lithium ion battery of the present disclosure will be described with reference to a method 1000 for manufacturing a honeycomb type lithium ion battery (hereinafter, sometimes referred to as “manufacturing method 1000 ”) as one embodiment.

[0058] The manufacturing method 1000 is a method for manufacturing a honeycomb lithium ion battery having a negative electrode, a positive electrode, and a separator layer. Figure 3 1 is a flow chart of manufacturing method 1000. Figure 3 As shown in FIG. 1 , the manufacturing method 1000 includes steps S1 to S3. In addition, the manufacturing method 1000 may include step S2a. Each step will be described below.

[0059] <Process S1>

[0060] Step S1 is a step of making a negative electrode having a plurality of through holes extending in a single direction. The method for making such a negative electrode having a honeycomb structure is not particularly limited, and it can be made, for example, by the following method. First, the negative electrode material constituting the negative electrode is mixed with a solvent (for example, water) to form a slurry. Next, the slurry is passed through a prescribed mold for extrusion molding, and heated for a prescribed time to dry it. In this way, a negative electrode can be made. Here, the drying temperature is not particularly limited, and is, for example, in the range of 50°C to 200°C. The drying time is not particularly limited, and is in the range of 10 minutes to 2 hours.

[0061] <Process S2>

[0062] Step S2 is performed after step S1, and is a step of configuring a separator layer (partition wall separator layer) on at least the inner wall of the through hole of the negative electrode. The method for configuring the separator layer in this way is not particularly limited, and it can be performed, for example, by the following method. First, the separator layer material constituting the separator layer (partition wall separator layer) is kneaded with a solvent (for example, an organic solvent) to form a paste. Next, the paste is configured on one surface (opening surface) in the through direction of the negative electrode, and suction is performed from the opposite side surface so that the paste adheres to the inner wall of the through hole. Next, the negative electrode with the paste attached is heated for a specified time to dry it. In this way, a separator layer (partition wall separator layer) can be configured on the inner wall of the through hole. Here, the drying temperature is not particularly limited, for example, in the range of 50°C to 200°C. The drying time is not particularly limited, and is in the range of 10 minutes to 2 hours.

[0063] <Step S2a>

[0064] Between step S2 and step S3, step S2a can be provided for further configuring an isolation layer (insulating film isolation layer) on the surface of the through-direction of the negative electrode (excluding the portion of the through-hole, the exposed surface of the negative electrode). The details are as follows. First, in step S2, if there is an excess isolation layer attached to the surface of the through-direction of the negative electrode, grind them with sandpaper or the like to expose the surface of the negative electrode. Next, the isolation layer material constituting the isolation layer (insulating film isolation layer) is added to the electroplating solution containing a binder and diffused evenly. Next, a metal electrode sheet (tab) (such as Ni, etc.) for electroplating is arranged on the side of the negative electrode. Then, the above-mentioned negative electrode is added to the prepared solution, a specified voltage is applied, and the isolation layer material is electroplated. After electroplating, the negative electrode is washed with water or the like, and heat-treated at a specified temperature. Thus, an isolation layer (insulating film isolation layer) can be arranged on the exposed surface of the negative electrode of the negative electrode.

[0065] <Process S3>

[0066] Step S3 is performed after step S2 or step S2a, and is a step of configuring a positive electrode inside the through-hole at least via a separator layer (partition separator layer). Specifically, first, the positive electrode material constituting the positive electrode is kneaded with a solvent (for example, an organic solvent) to form a paste. Next, the paste-like positive electrode material is arranged on one surface of the through-direction of the negative electrode. Next, the negative electrode is arranged inside the syringe, and the positive electrode material is pressed into the through-hole by applying pressure using the syringe. Then, it is heated for a prescribed time to dry it, so that the positive electrode (internal positive electrode) can be arranged inside the through-hole. In addition, thereby, the positive electrode (surface positive electrode) can also be arranged on one or two surfaces of the through-direction of the negative electrode. Here, the drying temperature is not particularly limited, for example, in the range of 50°C to 200°C. The drying time is not particularly limited, and is in the range of 10 minutes to 2 hours.

[0067] The battery obtained by step S3 is as follows Figure 2 As shown, the negative electrode and the positive electrode are physically separated from each other via a separator layer (a partition wall separator layer, an insulating film separator layer).

[0068] Here, the positive electrode (positive electrode material) contains a rod-shaped conductive agent, and by pressing the paste into the through-holes as described above, the rod-shaped conductive agent can be oriented in the through-hole penetration direction, thereby suppressing the DC resistance of the manufactured honeycomb lithium ion battery.

[0069] In addition to the above method, step S3 may also be a method of placing a paste positive electrode material on one surface of the negative electrode in the through-hole direction and sucking the positive electrode material from the other surface to flow into the through-hole. Even in this method, the rod-shaped conductive additive is oriented in the through-hole direction.

[0070] Here, when the manufactured battery is in a form using an electrolyte, a step of injecting the electrolyte into the entire interior of the electrode body (specifically, all cavities of the negative electrode 10 , the positive electrode 20 , and the separator layer 30 ) may be provided after step S3 (after the positive electrode is inserted).

[0071] The method for manufacturing the honeycomb type lithium ion battery of the present disclosure has been described above using the manufacturing method 1000. According to the method for manufacturing the honeycomb type lithium ion battery of the present disclosure, a honeycomb type lithium ion battery capable of suppressing direct current resistance can be manufactured.

[0072] Example

[0073] Hereinafter, the present disclosure will be further described using examples.

[0074] [Production of Evaluation Batteries]

[0075] Evaluation batteries of Examples 1 to 10 and Comparative Examples 1 to 3 were prepared as follows. The compositions of the positive electrodes of Examples 1 to 10 and Comparative Examples 1 to 3 and the average lengths of the rod-shaped conductive additives are shown in Table 1. The average length of the rod-shaped conductive additives was calculated as an average value of 30 rods.

[0076] <Example 1>

[0077] (Production of negative electrode)

[0078] 100 parts by weight of natural graphite particles with an average particle size of 15 μm, 10 parts by weight of carboxymethyl cellulose, and 60 parts by weight of ion exchange water are mixed to prepare a slurry. Next, the slurry is passed through a specified mold for extrusion molding and dried at 120°C for 3 hours to obtain a negative electrode. The negative electrode is a circle with a cross-sectional shape of φ20 mm, and a plurality of square through holes with a length of 250 μm on one side are provided in its surface. Adjacent through holes are arranged at equal intervals, and the interval (rib thickness) is 150 μm. The length of the through direction of the negative electrode is 1 cm.

[0079] (Configuration of the barrier rib layer)

[0080] 45 parts by weight of boehmite particles with an average particle size of 100 nm, 4 parts by weight of PVDF (manufactured by Kureha, #8500), and 40 parts by weight of NMP were mixed to make a paste. About 3 to 5 g of the paste was placed on an opening surface in the through-hole direction of the negative electrode, and a vacuum pump was used to suck from the opening surface on the opposite side so that the paste adhered to the inner wall of the through hole. Next, the negative electrode was dried at 120°C for 15 minutes to fix the partition wall separator layer to the inner wall of the through hole. The thickness of the partition wall separator layer was about 40 μm.

[0081] (Configuration of Insulating Film Spacer Layer)

[0082] The excess barrier rib separator layer adhered to the surface was polished with sandpaper on both sides of the opening in the through-direction of the negative electrode where the barrier rib separator layer was arranged, and the surface of the negative electrode was exposed.

[0083] Next, an insulating film separator layer is arranged on the exposed surface of the negative electrode on the surface in the through direction of the negative electrode. First, 30 parts by weight of boehmite particles with an average particle size of 100 nm and 90 parts by weight of ion exchange water are added to 25 parts by weight of a PI solution for electroplating (Elecourt PI, manufactured by Shimizu Co., Ltd.) in which polyimide particles are dispersed, and diffused until uniform. A negative electrode with a Ni pole piece previously wrapped on the side (circumferential side) is added to the solution. Next, the negative electrode side is made -, the working electrode side is made +, and a voltage of 15V is applied for 2 minutes to electroplated the separator layer on the open surface. The negative electrode after electroplating is gently washed with water to remove excess electroplating liquid, and heat treated at 180°C for 1 hour to arrange the insulating film separator layer on the two surfaces in the through direction of the negative electrode. The thickness of the insulating film separator layer is about 36μm.

[0084] (Positive electrode configuration)

[0085] 91 parts by weight of lithium cobalt oxide with an average particle size of 10 μm, 2 parts by weight of acetylene black, 4 parts by weight of milled fiber (XN-100-15M manufactured by Nippon Graphite Co., Ltd.) as a rod-shaped conductive aid, 3 parts by weight of PVDF (manufactured by Kureha Co., Ltd., #8500), and 30 parts by weight of NMP were mixed to prepare a positive electrode paste. Next, the above-mentioned negative electrode was fixed in a plastic syringe, 3.5 g of positive electrode paste was added to the syringe, and the positive electrode paste was injected into the through hole by applying pressure with the syringe. Stop pressing the syringe at the moment when it can be visually confirmed that the positive electrode paste comes out from the opening opposite to the injection side, take out the negative electrode from the plastic syringe and dry it at 120°C for 30 minutes. Thus, the evaluation battery of Example 1 was obtained.

[0086] <Examples 2 to 5>

[0087] Except that the composition of the positive electrode was changed as shown in Table 1, the same method as in Example 1 was carried out to obtain evaluation batteries of Examples 2 to 5.

[0088] <Example 6>

[0089] An evaluation cell of Example 6 was obtained in the same manner as in Example 1 except that the rod-shaped conductive auxiliary agent contained in the positive electrode was changed to milled fiber (XN-100-25M, manufactured by Nippon Graphite Co., Ltd.).

[0090] <Example 7>

[0091] An evaluation cell of Example 7 was obtained in the same manner as in Example 1 except that the rod-shaped conductive auxiliary agent contained in the positive electrode was changed to milled fiber (XN-100-05M, manufactured by Nippon Graphite Co., Ltd.).

[0092] <Example 8>

[0093] An evaluation battery of Example 8 was obtained in the same manner as in Example 1 except that the rod-shaped conductive additive contained in the positive electrode was changed to a fiber obtained by pulverizing ground fiber (XN-100-05M manufactured by Nippon Graphite Co., Ltd.) using a ball mill for 5 minutes.

[0094] <Example 9>

[0095] Except that the composition of the positive electrode was changed as shown in Table 1, the same method as in Example 1 was carried out to obtain an evaluation battery of Example 9.

[0096] <Example 10>

[0097] An evaluation cell of Example 10 was obtained in the same manner as in Example 1 except that the rod-shaped conductive additive contained in the positive electrode was changed to a fiber obtained by pulverizing ground fiber (XN-100-05M manufactured by Nippon Graphite Co., Ltd.) in a ball mill for 10 minutes.

[0098] <Comparative Examples 1 to 3>

[0099] Evaluation batteries of Comparative Examples 1 to 3 were obtained by the same method as in Example 1 except that the rod-shaped conductive auxiliary agent was not used and the composition of the positive electrode was changed as shown in Table 1.

[0100] [evaluate]

[0101] (Cross-section observation)

[0102] The evaluation battery of Example 1 was cut in the through-going direction, and its cross section was observed using an optical microscope. The results are shown in FIG. Figure 4 .

[0103] (Measurement of DC resistance between positive electrodes)

[0104] Positive electrode current collectors were placed on both surfaces of the evaluation battery in the through-going direction, and the resistance between the positive electrode current collectors was measured using a tester.

[0105] [Table 1]

[0106]

[0107] [result]

[0108] according to Figure 4 It can be confirmed that the rod-shaped conductive additive contained in the positive electrode of Example 1 is oriented in the through-hole direction. From this result, it can be seen that the rod-shaped conductive additive can be oriented in the through-hole direction by pressing the positive electrode paste into the through-hole of the negative electrode.

[0109] According to Table 1, when comparing Examples 1 to 3 and 9 with Comparative Example 1, it was confirmed that the resistance between the positive electrodes can be suppressed by containing a small amount of the rod-shaped conductive auxiliary agent. In addition, if the content of the rod-shaped conductive auxiliary agent is 2% by weight or more, it can be confirmed that the resistance between the positive electrodes is significantly suppressed. Based on this result, it is believed that the greater the content of the rod-shaped conductive auxiliary agent, the greater the resistance suppression effect between the positive electrodes.

[0110] The results of Examples 1 and 5 and Examples 3 and 4 confirmed that the positive electrode resistance can be further suppressed by using a particulate conductive agent together with a rod-shaped conductive agent. On the other hand, the results of Comparative Examples 1 to 3, which did not use a rod-shaped conductive agent, were inferior to the results of all Examples using a rod-shaped conductive agent. This is a result that even if the content of the particulate conductive agent is increased, the effect of adding a rod-shaped conductive agent cannot be obtained.

[0111] The results of Examples 1, 6 to 8, and 10 show that the resistance suppression effect increases as the average length of the rod-shaped conductive additive increases. This is considered to be because the longer the rod-shaped conductive additive, the easier it is to form a conductive path in the positive electrode.

Claims

1. A honeycomb lithium ion battery having a negative electrode, a positive electrode and a separator layer, characterized in that: The negative electrode has a plurality of through holes extending in one direction, The separator layer has Li ion permeability and is at least arranged on the inner wall of the through hole to physically separate the negative electrode from the positive electrode. The positive electrode is disposed inside the through hole at least via the separator layer. The positive electrode comprises a rod-shaped conductive auxiliary agent, The rod-shaped conductive additive is oriented in the penetration direction of the through hole, The shape of the through hole in a direction perpendicular to the through hole direction is any one of a circle, a rectangle, and a hexagon. The rod-shaped conductive additive is a fibrous carbon material. The length of the rod-shaped conductive additive is not less than 10 μm and not more than the shortest length of the diameter of the through hole. When the shape in the direction perpendicular to the penetration direction of the through hole is a circle, the shortest length of the aperture of the through hole refers to the length of the diameter; when the shape in the direction perpendicular to the penetration direction of the through hole is a rectangle, the shortest length of the aperture of the through hole refers to the length of the short side; when the shape in the direction perpendicular to the penetration direction of the through hole is a hexagon, the shortest length of the aperture of the through hole refers to the shortest length of the line connecting two opposite sides at right angles.

2. The honeycomb lithium ion battery according to claim 1, wherein: The rod-shaped conductive additive is ground fiber.

3. The honeycomb lithium ion battery according to claim 1 or 2, wherein: The length of the rod-shaped conductive auxiliary agent is 30 μm or more.

4. A method for manufacturing a honeycomb lithium-ion battery, which is a method for manufacturing a honeycomb lithium-ion battery having a negative electrode, a positive electrode and a separator layer, characterized in that: The following processes are available: a step of manufacturing the negative electrode having a plurality of through holes extending in one direction, a step of disposing the spacer layer at least on the inner wall of the through hole, and a step of disposing the positive electrode inside the through hole at least via the separator layer; The separator layer has Li ion permeability and physically separates the negative electrode from the positive electrode. The positive electrode comprises a rod-shaped conductive auxiliary agent, In the step of configuring the positive electrode, the paste-like positive electrode material constituting the positive electrode is pressed into the through hole of the negative electrode configured with the separator layer, thereby orienting the rod-like conductive additive in the penetrating direction of the through hole. The shape of the through hole in a direction perpendicular to the through hole direction is any one of a circle, a rectangle, and a hexagon. The rod-shaped conductive additive is a fibrous carbon material. The length of the rod-shaped conductive additive is not less than 10 μm and not more than the shortest length of the diameter of the through hole. When the shape in the direction perpendicular to the penetration direction of the through hole is a circle, the shortest length of the aperture of the through hole refers to the length of the diameter; when the shape in the direction perpendicular to the penetration direction of the through hole is a rectangle, the shortest length of the aperture of the through hole refers to the length of the short side; when the shape in the direction perpendicular to the penetration direction of the through hole is a hexagon, the shortest length of the aperture of the through hole refers to the shortest length of the line connecting two opposite sides at right angles.

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