JP-7854658-B2 - Negative electrode for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery

Inventors

• 鍛治 宗騎
• 星原 悠司
• 田中 真奈
• 石川 正司
• 日野 泰誠

Assignees

• 第一工業製薬株式会社
• 学校法人 関西大学

Dates

Publication Date

20260507

Application Date

20220930

Claims (7)

1. A negative electrode for a non-aqueous electrolyte secondary battery, comprising a current collector and a layer containing polyurethane resin and single-walled carbon nanotubes disposed on the current collector, and not containing a negative electrode active material.
2. The negative electrode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the polyurethane resin comprises a lithium salt and/or a sodium salt of an anionic polyurethane resin.
3. The anode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the polyurethane resin contains an alicyclic polyisocyanate as a raw material.
4. The negative electrode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the mass ratio (A)/(B) of the polyurethane resin (A) to the single-walled carbon nanotube (B) is 99.9/0.1 to 97.0/3.0.
5. The negative electrode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the thickness of the layer containing the polyurethane resin and the single-walled carbon nanotube is 0.5 to 2 μm.
6. A non-aqueous electrolyte secondary battery comprising a negative electrode for a non-aqueous electrolyte secondary battery as described in any one of claims 1 to 5.
7. A non-aqueous electrolyte secondary battery according to claim 6, using an ionic liquid as the electrolyte.

Description

Embodiments of the present invention relate to a negative electrode for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery using the same. Non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, are used as high-voltage, high-energy-density energy storage devices, for example, as power sources for electronic devices. The negative electrode of a non-aqueous electrolyte secondary battery is typically fabricated by coating and drying a mixture containing a negative electrode active material, a conductive additive, and a binder onto a current collector to form a negative electrode active material layer; the negative electrode active material is considered an essential component. For example, Patent Document 1 describes that the composite electrode corresponding to the negative electrode active material layer formed on the current collector includes a negative electrode active material, carbon nanotubes as a conductive additive, and a binder such as polyvinylidene fluoride. Japanese Patent Publication No. 2015-153714 This is a schematic diagram of a non-aqueous electrolyte secondary battery according to one embodiment.This is an exploded perspective view of the evaluation cell used in the example. The negative electrode for a non-aqueous electrolyte secondary battery according to this embodiment comprises a current collector and a layer (hereinafter sometimes referred to as the "CNT layer") containing polyurethane resin and single-walled carbon nanotubes disposed on the current collector. [Current collector] The current collector is not particularly limited as long as it has electronic conductivity and can extract current to the outside. The current collector can be formed from, for example, metal materials such as copper, stainless steel, aluminum, nickel, and titanium, conductive polymers, and conductive glass. In one embodiment, the current collector may be a metal layer formed from an electronically conductive metal material. The metal layer may be, for example, a metal layer such as copper whose surface is treated with tin, nickel, titanium, or silver, or the surface of the metal layer may be oxidized. The shape of the current collector is not particularly limited. For example, the current collector may be in the form of a film, such as a foil of a metal material, or it may be in the form of a sheet, plate, or molded body such as a porous material or foam. The current collector may also be, for example, a metal layer formed on a resin film or sheet. The thickness of the current collector is not particularly limited; for example, it may be 1 to 1000 μm, 5 to 100 μm, or 10 to 50 μm. [CNT layer] The CNT layer is a layer containing single-walled carbon nanotubes as a conductive material and polyurethane resin as a binder, and is electrically conductive. The CNT layer is a layer formed on the current collector (i.e., on the surface of the current collector) in place of the conventional negative electrode active material layer, and does not contain negative electrode active material. The CNT layer formed on the current collector may be provided on one side of the current collector or on both sides. Single-walled carbon nanotubes (SWCNTs) are a type of carbon nanotube that has a single-walled structure, consisting of a cylindrical coil of six-membered rings (graphene sheets) made of carbon. The diameter (fiber diameter) of the single-walled carbon nanotube is not particularly limited; the average diameter may be, for example, 0.4 to 100 nm, 0.5 to 10 nm, or 1.0 to 5.0 nm. The length of the single-walled carbon nanotube is not particularly limited; the average length may be, for example, 50 nm to 1 mm, or 0.5 to 100 μm. The aspect ratio (i.e., the ratio of the average length to the average diameter) of the single-walled carbon nanotube is not particularly limited; for example, it may be 10 or more, or 100 or more. Here, the average diameter and average length of single-walled carbon nanotubes can be determined by measuring the dimensions of 50 randomly selected single-walled carbon nanotubes in atomic force microscope images and taking their arithmetic mean. Lengths on the millimeter order that cannot be measured by atomic force microscopy can be measured using microscope images. Various water-based polyurethane resins can be used as the polyurethane resin, such as anionic polyurethane resins, cationic polyurethane resins, or nonionic polyurethane resins. Anionic polyurethane resins are water-dispersible, aqueous polyurethane resins having anionic groups. Examples of anionic groups include carboxyl groups, sulfonic acid groups, phosphate groups, and salts thereof. These anionic groups may be present individually or in combination of two or more. Examples of salts include alkali metal salts such as lithium salts, sodium salts, and potassium salts, ammonium salts, and amine salts such as primary amines, secondary amines, and tertiary amines. Examples of an