Aluminum Current Collector Surface with Superimposed Wave Structures

Solution Overview

Problem

Current aluminum bases for current collectors in secondary batteries have inadequate adhesion to active material layers, leading to poor battery characteristics and cycle performance.

Innovation Solution

An aluminum base with a surface featuring superimposed large-wave, medium-wave, and small-wave structures of specific average opening sizes, enhancing adhesion by increasing the contact area with active material layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional aluminum base surfaces are used, then manufacturing is simple, but adhesion to active material layers is insufficient

Engineering Contradiction:

Improveadhesion strengthVSAvoidsurface structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The surface is segmented into multiple hierarchical wave structures with different spatial frequencies (large-wave, medium-wave, and small-wave structures). Each wave structure type has a specific average opening size range, creating a multi-scale rough surface that enhances adhesion through increased contact area and mechanical interlocking with the active material layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the surface exhibit different local structures (large-wave, medium-wave, small-wave) with specific opening sizes. The large-wave structure (5-100 μm) provides primary mechanical interlocking, while medium-wave (0.5-5 μm) and small-wave (0.01-0.5 μm) structures create additional contact points and increase effective surface area for adhesion.

Inventive Principle:

Principle #3Local quality

2Strength

If surface roughening is applied to improve adhesion, then contact area increases, but cycle characteristics deteriorate

Engineering Contradiction:

Improveadhesion strengthVSAvoidcycle characteristics

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The surface is segmented into multiple hierarchical wave structures with different spatial frequencies (large-wave, medium-wave, and small-wave structures). Each wave structure type has a specific average opening size range, creating a multi-scale rough surface that enhances adhesion through increased contact area and mechanical interlocking with the active material layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The wave structures create curved surface profiles with specific peak-to-valley height constraints (Pt ≤ 10 μm). The curvature of these wave structures provides optimal mechanical interlocking without creating stress concentration points that would lead to delamination during battery cycling.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If multi-scale wave structures are superimposed, then adhesion and cycle characteristics improve, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecycle characteristicsVSAvoidsurface structure precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The surface is segmented into multiple hierarchical wave structures with different spatial frequencies (large-wave, medium-wave, and small-wave structures). Each wave structure type has a specific average opening size range, creating a multi-scale rough surface that enhances adhesion through increased contact area and mechanical interlocking with the active material layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention specifies precise parameter ranges for the wave structures: large-wave average opening size of 5-100 μm, medium-wave of 0.5-5 μm, and small-wave of 0.01-0.5 μm. These parameter specifications provide clear manufacturing targets while allowing sufficient tolerance ranges to accommodate normal manufacturing variations.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9577264B2Aluminum base for current collector, current collector, positive electrode, negative electrode, and secondary battery

Publication Date: 2017.02.21 FUJIFILM CORP

AI summary

The purpose of this invention is to provide an aluminum base for a current collector, which enables the production of a secondary battery having excellent cycle properties; and a current collector, a positive electrode, a negative electrode and a secondary battery, each of which is produced using the aluminum base. The aluminum base for a current collector has a surface in which at least two structures selected from the group consisting of a large-wave structure having an average opening size of more than 5 μm but up to 100 μm, a medium-wave structure having an average opening size of more than 0.5 μm but up to 5 μm, and a small-wave structure having an average opening size of more than 0.01 μm but up to 0.5 μm are superimposed on one another, wherein a maximum peak-to-valley height Pt of a profile curve of the surface is up to 10 μm.