Electrode Laminate Surface Roughness for Low-Bubble Solid-State Batteries

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Solution Overview

Problem

In all-solid-state battery manufacturing, increasing surface roughness of the base layer to enhance interlayer adhesion can lead to bubble formation in the upper layer, degrading battery performance.

Innovation Solution

Control the arithmetic mean height (Sa) of the first layer's surface to be between 0.1 μm and 0.2 μm, allowing the slurry to penetrate without forming excessive bubbles, while maintaining sufficient interlayer adhesion strength by adjusting the roll linear pressure and particle size distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If surface roughness of the first layer is increased to improve interlayer adhesion strength, then adhesion strength is improved, but bubble generation in the second layer increases

Engineering Contradiction:

Improveinterlayer adhesion strengthVSAvoidbubble generation

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by precisely controlling the arithmetic mean height (Sa) of the first layer's surface within the range of 0.05 μm to 0.2 μm. This quantitative parameter optimization resolves the contradiction by finding the optimal surface roughness level that provides sufficient anchor effect for adhesion while limiting void formation that causes bubbles during slurry coating.

Inventive Principle:

Principle #35Parameter changes

2Strength

If surface roughness is increased to create anchor portions for adhesion, then interlayer adhesion is improved, but voids at the surface increase causing bubble formation

Engineering Contradiction:

Improveinterlayer adhesion strengthVSAvoidbubble density control

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent uses parameter changes by defining the optimal Sa range (0.05-0.2 μm) that balances anchor effect and void minimization. Additionally, it controls the maximum pore diameter of the first layer to be 0.215 μm to 0.240 μm, providing dual parameter control to achieve both strong adhesion and low bubble density (less than 6 bubbles/cm²).

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional mechanical approach of simply increasing surface roughness with a more refined control mechanism based on statistical surface parameters (Sa and maximum pore diameter). This substitution allows precise control over the balance between adhesion promotion and bubble prevention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach reduces bubble density in the second layer to less than 6 bubbles/cm² and improves interlayer adhesion strength, enhancing battery performance by optimizing the contact area between layers.

Implementation Method 1

Part of the slurry penetrates into voids at a surface of the first layer. Anchor portions are formed by solidification of the slurry that has penetrated the voids

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

Anchor portions are formed by solidification of the slurry that has penetrated the voids at the surface of the first layer

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentUS20230352647A1Electrode laminate manufacturing method, all-solid-state battery manufacturing method, electrode laminate, and all-solid-state battery

Publication Date: 2023.11.02 TOYOTA JIDOSHA KK

AI summary

A first layer is formed. A second layer is formed by coating a slurry onto a surface of the first layer. The second layer is subjected to pressing, thereby manufacturing an electrode laminate. The forming of the first layer is performed such that a relation of an Expression “0.1<Sa<0.2” is satisfied. In the Expression, Sa (μm) represents an arithmetic mean height of the surface of the first layer.