Graphite Electrode Structure for Lower-Resistance Li-Ion Batteries

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Solution Overview

Problem

There is a need to improve the rate characteristic of power storage devices such as lithium-ion secondary batteries, as existing technologies do not effectively address the charging/discharging characteristics.

Innovation Solution

An electrode for power storage devices is developed, comprising a resin layer, a conductive layer containing copper, and an active material layer containing graphite. The conductive layer is optimized by ensuring a specific peak intensity ratio of X-ray diffraction peaks, which enhances the crystallinity and reduces the electrical resistance of the conductive layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a composite material with conductive layers on both sides of a resin film is used as a current collector, then the structural stability is improved, but the rate characteristic deteriorates

Engineering Contradiction:

Improvestructural stabilityVSAvoidrate characteristic

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent changes the crystallographic orientation parameters of the copper conductive layer by controlling the plating conditions to achieve a specific (200) plane orientation. This parameter change in crystal structure reduces electrical resistance and improves electron transport, thereby enhancing the rate characteristic while maintaining the composite structure's stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite material consisting of a resin film with copper conductive layers formed on both sides. This composite structure combines the mechanical stability of the resin film with the electrical conductivity of copper, achieving both structural stability and improved rate characteristic through optimized copper crystal orientation

Inventive Principle:

Principle #40Composite materials

2Reliability

If the conductive layer is made thinner to reduce resistance, then the electrical conductivity is improved, but the mechanical strength deteriorates

Engineering Contradiction:

Improveelectrical conductivityVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent employs thin copper conductive layers (0.01-5 μm) formed on the resin film surface. These thin films provide sufficient electrical conductivity for current collection while the underlying resin film provides the mechanical strength and structural support, resolving the contradiction between thinness for conductivity and strength for durability

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The composite structure of resin film plus thin copper layers allows the system to achieve high electrical conductivity through the copper while the resin matrix provides mechanical integrity. The combination enables thin conductive layers without sacrificing overall structural strength

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The optimized electrode improves the discharge rate characteristic of power storage devices by lowering the internal resistance, thereby enhancing the overall performance of lithium-ion secondary batteries.

Implementation Method 1

when measured by an X-ray diffraction method from a surface of the active material layer, a peak intensity ratio A/B between an intensity A at a highest X-ray diffraction peak in a range where a diffraction angle (2θ) is 48° or more and 53° or less and an intensity B at a highest X-ray diffraction peak in a range where a diffraction angle (2θ) is 52° or more and 57° or less satisfies Expression (1) below

Methodology Applied

Scientific EffectX-ray diffraction: X-Ray

Implementation Method 2

The conductive layer is optimized by ensuring a specific peak intensity ratio of X-ray diffraction peaks, which enhances the crystallinity and reduces the electrical resistance of the conductive layer

Methodology Applied

Scientific EffectCrystallinity: Crystallisation

Implementation Method 3

a conductive layer containing copper and being disposed on the resin layer

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

an active material layer containing graphite and being disposed on the conductive layer

Methodology Applied

Scientific EffectLithium-ion intercalation: Absorption (physical)

Data Source

PatentUS12341194B2Electrode for power storage devices and lithium-ion secondary battery

Publication Date: 2025.06.24 TDK CORP

AI summary

An electrode for power storage devices includes: a resin layer; a conductive layer containing copper and being disposed on the resin layer; and an active material layer containing graphite and being disposed on the conductive layer, wherein when measured by an X-ray diffraction method from a surface of the active material layer, a peak intensity ratio A/B between an intensity A at a highest X-ray diffraction peak in a range where a diffraction angle is 48° or more and 53° or less and an intensity B at a highest X-ray diffraction peak in a range where a diffraction angle is 52° or more and 57° or less satisfies Expression (1): 0.3≤A/B≤1 (1).