Solid Battery Thermal Expansion Control via Glass Transition Optimization

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Solution Overview

Problem

Current solid batteries face challenges in achieving improved battery characteristics and reliability due to differences in thermal expansion among constituent elements during the sintering process, leading to issues like cracking, warpage, and internal short-circuits.

Innovation Solution

Incorporating materials with a glass transition point of 500°C or less in the positive electrode, negative electrode, solid electrolyte, current collecting, and insulating layers, ensuring a volume ratio of 10-60% and a maximum content difference of 30% or less, which enhances ionic conductivity and reduces deformation during sintering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional solid battery materials are used in the sintering process, then battery structure is formed, but thermal expansion differences cause cracking, warpage, and internal short-circuits

Engineering Contradiction:
Improvebattery structure integrityVSAvoidbattery reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by controlling the glass transition temperature of the binder material to be 500°C or lower, and optimizing its content to 10-60 vol% in each layer. This parameter optimization allows the binder to effectively suppress thermal expansion differences during sintering without compromising battery reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by incorporating a binder containing glass powder with specific glass transition temperature into all battery layers (positive electrode, negative electrode, solid electrolyte, current collecting, and insulating layers). This composite approach creates a unified material system that coordinates thermal expansion across different functional layers

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If glass content is increased to suppress deformation, then manufacturing precision improves, but ionic conductivity may be affected

Engineering Contradiction:
Improvedeformation suppressionVSAvoidionic conductivity
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent optimizes the glass content parameter to a specific range of 10-60 vol% in each layer, with the glass transition temperature controlled at 500°C or lower. This parameter optimization ensures sufficient deformation suppression while maintaining adequate ionic conductivity for battery operation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by ensuring that each functional layer (positive electrode, negative electrode, solid electrolyte, current collecting, and insulating layers) contains the binder material within the specified composition range, creating localized quality control that maintains both structural integrity and ionic conductivity in different regions

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 significantly improves battery characteristics and reliability by suppressing deformation, cracking, and internal short-circuits, allowing stable operation and high energy density in solid batteries.

Implementation Method 1

incorporating materials with a glass transition point of 500°C or less in the positive electrode, negative electrode, solid electrolyte, current collecting, and insulating layers

Methodology Applied
Scientific EffectGlass transition:

Implementation Method 2

differences in thermal expansion among constituent elements during the sintering process, leading to issues like cracking, warpage, and internal short-circuits

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

a solid battery using a solid electrolyte in place of a liquid electrolyte has been extensively researched and developed

Methodology Applied
Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentEP3699995B1Solid state battery, battery pack, vehicle, power storage system, electric tool and electronic apparatus
Publication Date: 2022.12.28 MURATA MFG CO LTD
  • EP3699995B1 patent drawingFigure 1A~1C
  • EP3699995B1 patent drawingFigure 2~3
  • EP3699995B1 patent drawingFigure 4~5

AI summary

To provide a solid battery having excellent battery characteristics and excellent reliability. There is provided a solid battery including: a positive electrode layer; a negative electrode layer; a current collecting layer; a solid electrolyte layer; and an insulating layer, where each of the positive electrode layer, the negative electrode layer, the current collecting layer, the solid electrolyte layer, and the insulating layer contains a material having a glass transition point of 500°C or less in an amount of 10 vol% or more and 60 vol% or less, and among the contents of the material having a glass transition point of 500°C or less in each of the positive electrode layer, the negative electrode layer, the current collecting layer, the solid electrolyte layer, and the insulating layer, a difference between a maximum content and a minimum content is 30 vol% or less.