Composite Solid Electrolyte for Low-Temperature Lithium-Ion Conduction

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Solution Overview

Problem

Existing technologies face challenges in achieving high lithium ion conductivity while using a sintering temperature of not more than 600°C, both in the case of single and combined solid electrolyte materials.

Innovation Solution

A lithium ion conductor composite material comprising a first lithium ion conductor with higher ion conductivity and a second lithium ion conductor with lower sintering temperature is used, where the first conductor has a sintering temperature above 600°C and the second conductor has a sintering temperature below 600°C, allowing for high ion conductivity at or below 600°C.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-temperature sintering (not less than 700°C) is used to achieve high ion conductivity in oxide-based solid electrolytes, then ion conductivity is improved, but harmful reactions occur between electrode active material and oxygen in the solid electrolyte

Engineering Contradiction:
Improveion conductivityVSAvoidreaction between electrode active material and oxygen
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention uses a composite solid electrolyte consisting of a crystal phase (perovskite or garnet type) and a glass ceramic phase. The glass ceramic component acts as a low-temperature sintering aid that enables the crystal phase to form and achieve high ion conductivity at temperatures of 600°C or lower, preventing harmful reactions while maintaining excellent ion conductivity

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the sintering temperature parameter from the conventional high temperature (700°C or higher) to a lower temperature (600°C or lower) by introducing a glass ceramic phase. This parameter change is achieved by controlling the composition ratios of the crystal phase and glass ceramic phase, where the glass ceramic phase serves as a flux that lowers the sintering temperature while still enabling the formation of the high-conductivity crystal phase

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If sintering temperature is reduced to or below 600°C to prevent harmful reactions, then harmful reactions are suppressed, but ion conductivity becomes insufficient

Engineering Contradiction:
Improvereaction between electrode active material and oxygenVSAvoidion conductivity
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The composite structure combines a crystal phase (which provides high ion conductivity when properly formed) with a glass ceramic phase (which enables low-temperature sintering). The glass ceramic acts as a sintering aid that facilitates the formation of the crystal phase at low temperatures, thereby achieving both low sintering temperature and high ion conductivity simultaneously

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The glass ceramic phase serves as an intermediary substance that mediates between the low sintering temperature requirement and the high ion conductivity requirement. It acts as a flux or sintering aid that enables the crystal phase to form and sinter properly at temperatures of 600°C or lower, which would otherwise be insufficient for achieving high ion conductivity

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enables high lithium ion conductivity while maintaining a sintering temperature below 600°C, preventing reactions between the electrode active material and oxygen in the solid electrolyte, enhancing battery safety and design flexibility.

Implementation Method 1

a first lithium ion conductor (1) and a second lithium ion conductor (2), the lithium ion conductivity of which is higher than that of the second lithium ion conductor (2)

Methodology Applied
Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

it is necessary to sinter the solid electrolyte at a high temperature of not less than 700°C

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP3242300B1Lithium ion conductor, solid electrolyte layer, electrode, battery and electronic device
Publication Date: 2025.09.03 MURATA MFG CO LTD
  • EP3242300B1 patent drawingFigure 1~2B
  • EP3242300B1 patent drawingFigure 3

AI summary

A lithium ion conductor includes a first lithium ion conductor that contains at least one selected from among oxide crystals and glass ceramics, and a second lithium ion conductor that has a sintering temperature of not more than 600°C. The lithium ion conductivity of the first lithium ion conductor is higher than the lithium ion conductivity of the second lithium ion conductor.