All-Solid-State Battery Electrolyte Layer for Warpage-Free Packing

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Solution Overview

Problem

In all-solid-state batteries, using small average particle diameter solid electrolyte particles for the solid electrolyte layer results in low packing density and pressure unevenness, leading to density unevenness and warpage of the solid electrolyte layer.

Innovation Solution

Incorporating second solid electrolyte particles with a larger average particle diameter than the first solid electrolyte particles in the electrodes, enhancing their flowability and packing density through a dry process, while maintaining high ion conductivity by using ion-conductive particles with a median diameter of 1 μm or more and 50 μm or less in the solid electrolyte layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solid electrolyte particles with small average particle diameter are used to form the solid electrolyte layer, then ion conductivity is improved, but packing density decreases and pressure unevenness occurs during press-molding

Engineering Contradiction:

Improveion conductivityVSAvoidpacking density uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by using solid electrolyte particles with different average particle diameters in different regions: smaller particles (first solid electrolyte particles) in the electrodes for high ion conductivity, and larger particles (second solid electrolyte particles) in the solid electrolyte layer for high packing density and uniformity. This spatial differentiation of particle sizes resolves the contradiction between ion conductivity and packing density uniformity.

Inventive Principle:

Principle #3Local quality

2Reliability

If solid electrolyte particles with small average particle diameter are used, then contact resistance between particles is reduced, but density unevenness occurs in the solid electrolyte layer after press-molding

Engineering Contradiction:

Improvecontact resistanceVSAvoiddensity uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements local quality by differentiating particle size based on functional requirements: small particles in electrodes for low contact resistance, and large particles in the solid electrolyte layer for uniform density distribution during press-molding, thereby resolving the contradiction between contact resistance and density uniformity.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If solid electrolyte particles with small average particle diameter are used, then the solid electrolyte layer can be formed, but warpage occurs due to pressure unevenness

Engineering Contradiction:

Improvesolid electrolyte layer formationVSAvoidwarpage

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The patent applies local quality by using larger second solid electrolyte particles specifically in the solid electrolyte layer to ensure uniform pressure distribution during press-molding, preventing warpage while maintaining the ability to form the layer. This resolves the contradiction between ease of manufacture and shape stability.

Inventive Principle:

Principle #3Local quality

4Quantity of substance

If larger solid electrolyte particles are used in the solid electrolyte layer, then packing density increases, but ion conductivity may decrease

Engineering Contradiction:

Improvepacking densityVSAvoidion conductivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent resolves this contradiction by applying local quality: using larger particles only in the solid electrolyte layer where packing density is critical, while using smaller particles in the electrodes where ion conductivity is paramount. This spatial differentiation allows both high packing density and high ion conductivity to be achieved in their respective locations.

Inventive Principle:

Principle #3Local quality

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 secures high ion conductivity and suppresses warpage of the solid electrolyte layer, achieving a packing density of 99 vol% or more and reducing interlayer resistance for higher energy density.

Implementation Method 1

An electrode group formed by laminating the electrodes and the solid electrolyte layer are pressed at a pressure of approximately 5×10³ kgf/cm²

Methodology Applied

Scientific EffectPressure: Pressure Increase

Implementation Method 2

The solid electrolyte layer is typically formed by applying a slurry containing a solid electrolyte on an electrode surface, and drying the slurry

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS11876171B2All-solid-state battery and production method of the same

Publication Date: 2024.01.16 HITACHI ZOSEN CORP

AI summary

Disclosed is an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode. At least one of the positive electrode and the negative electrode contains first solid electrolyte particles. The solid electrolyte layer contains second solid electrolyte particles having ion conductivity. An average particle diameter D1 of the first solid electrolyte particles, and an average particle diameter D2 of the second solid electrolyte particles satisfy D2>D1.