US-12620600-B2 - Honeycomb type lithium ion battery

US12620600B2US 12620600 B2US12620600 B2US 12620600B2US-12620600-B2

Abstract

Provided is a honeycomb type lithium ion battery capable of suppressing short-circuiting due to cracks. The honeycomb type lithium ion battery has an anode, a cathode, and a separator layer, wherein the anode has a plurality of through holes extending in one direction, the separator layer has partition separator layers and insulating film separator layers, the cathode has inner areas disposed inside the through holes via the partition separator layers, intermediate areas disposed over faces of the inner areas and faces of the insulating film separator layers, and a surface area with which surfaces of the insulating film separator layers and the intermediate areas are covered, and the cathode contains a binder, wherein the proportion of the content of the binder in the surface area is high compared to the proportion of the content of the binder in the inner areas.

Inventors

Masaharu Senoue

Assignees

TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date: 20260505
Application Date: 20220311
Priority Date: 20210326

Claims (1)

1 . A honeycomb type lithium ion battery having an anode, a cathode, and a separator layer, wherein the anode has a plurality of through holes extending in one direction, the separator layer has Li ion permeability, physically isolates the anode and the cathode from each other, and has partition separator layers and insulating film separator layers, insides of the through holes being covered with the partition separator layers, opening face parts on one and another sides of the through holes being covered with the insulating film separator layers, the cathode has inner areas disposed inside the through holes via the partition separator layers, intermediate areas disposed over faces of the inner areas and faces of the insulating film separator layers, and a surface area with which surfaces of the insulating film separator layers and the intermediate areas are covered, and the cathode contains a binder, wherein a proportion of a content of the binder in the surface area is 2 wt % or more and 5 wt % or less, and a proportion of a content of the binder in the inner areas is 1 wt % or less.

Description

FIELD The present application relates to a honeycomb type lithium ion battery. BACKGROUND Patent Literature 1 discloses a honeycomb-structure current collector for an electrode of a lithium ion secondary battery which is formed by coating, with a titanium nitride film, the surfaces of partitions of cells which include the outer surface of a carbonaceous honeycomb structure, and an electrode of a lithium ion secondary battery which is formed by filling the cells of this current collector with an active material for a cathode or an anode. CITATION LIST Patent Literature Patent Literature 1: JP 2001-126736 A SUMMARY Technical Problem As a result of his intensive research on the honeycomb type lithium ion battery, the inventor of the present application found out that when a separator is disposed in through holes of an anode having a honeycomb structure, next a cathode paste is disposed in the through holes, and thereafter a solvent in the cathode paste is dried, shrinkage stress of a binder in the cathode paste applies tensile stress to the separator, which may cause cracks in the battery. The inventor also found out that such cracks may cause the cathode and the anode to be in contact with each other to short-circuit. In view of the above circumstances, an object of the present disclosure is to provide a honeycomb type lithium ion battery capable of suppressing short-circuiting due to cracks. Solution to Problem As one aspect to solve the above problem, the present disclosure is provided with a honeycomb type lithium ion battery having an anode, a cathode, and a separator layer, wherein the anode has a plurality of through holes extending in one direction, the separator layer has Li ion permeability, physically isolates the anode and the cathode from each other, and has partition separator layers and insulating film separator layers, insides of the through holes being covered with the partition separator layers, at least one of opening face parts on one and another sides of the anode being covered with the insulating film separator layers, the cathode has inner areas disposed inside the through holes via the partition separator layers, intermediate areas disposed over faces of the inner areas and faces of the insulating film separator layers, and a surface area with which surfaces of the insulating film separator layers and the intermediate areas are covered, and the cathode contains a binder, wherein a proportion of a content of the binder in the surface area is high compared to a proportion of a content of the binder in the inner areas. Advantageous Effects In the honeycomb type lithium ion battery according to the present disclosure, a proportion of the content of the binder in the surface areas is high compared to that in the inner areas. A lower proportion of the content of the binder in the inner areas in the cathode as described above can reduce shrinkage stress that the cathode gives the separator layer in a drying step in a manufacturing process, to suppress cracks. The suppression of cracks can lead to suppression of short-circuiting due to such cracks. A higher proportion of the content of the binder in the surface areas in the cathode makes it possible to retain the shape of the cathode. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view of an anode 10; FIG. 2 is a schematic cross-sectional view of a honeycomb type lithium ion battery 100; FIG. 3 is a photograph of a cracking honeycomb type lithium ion battery; and FIG. 4 is a flowchart of a method 1000 of manufacturing a honeycomb type lithium ion battery. DESCRIPTION OF EMBODIMENTS [Honeycomb Type Lithium Ion Battery] A honeycomb type lithium ion battery according to the present disclosure will be described, making reference to a honeycomb type lithium ion battery 100 that is one embodiment (hereinafter may be referred to as “battery 100”). FIG. 1 is a perspective view of an anode 10. FIG. 2 is a schematic cross-sectional view of the battery 100 taken along the penetrating direction of through holes 11 of the anode 10. As in FIG. 2, the battery 100 includes the anode 10, a cathode 20 and a separator layer 30. The battery 100 may be also provided with an anode current collector 40 and a cathode current collector 50. <Anode 10> The anode 10 has a plurality of the through holes 11 extending in one direction (penetrating direction). Such a structure is called a so-called honeycomb structure. The entire shape of the anode 10 is not particularly limited, but may be a quadrangular prism as in FIG. 1, any other prism, or a cylinder. The entire size of the anode 10 is not particularly limited, but may be suitably set according to the purpose. For example, a height of the anode 10 (length in the penetrating direction, h) may be 3 mm to 100 mm in view of improving strength. A diameter (d) of the anode 10 may be 10 mm to 100 mm. Further, an aspect ratio (h/d) of the height (h) to the diameter (d) of the anode 10 may be 0.1 to 10. A shape of each of