Li-La-Zr-O Solid Electrolyte Denseness via Si-Al Ratio

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Solution Overview

Problem

Li-La-Zr-O-based solid electrolyte materials with Al content suffer from reduced denseness, which affects their lithium ion conductivity and mechanical strength.

Innovation Solution

Incorporating Si into the Li-La-Zr-O-based solid electrolyte material with a specific Al/Si ratio of 0.61 to 11.9% by weight, forming a garnet structure sintered body, enhances denseness and lithium ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Al is added to Li-La-Zr-O-based solid electrolyte material, then lithium ion conductivity is improved, but denseness deteriorates

Engineering Contradiction:
Improvelithium ion conductivityVSAvoiddenseness
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent changes the chemical composition parameters by introducing Si into the Li-La-Zr-O-Al system and optimizing the Al/Si weight ratio to within 0.61 to 11.9. This parameter modification allows the material to achieve both high lithium ion conductivity and high denseness (95% or more), resolving the contradiction between improving conductivity and maintaining denseness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite solid electrolyte material by combining multiple elements (Li, La, Zr, Al, Si, O) in specific proportions. The composite structure with controlled Al/Si ratio enables synergistic effects where Al contributes to lithium ion conductivity while Si helps maintain high denseness, achieving both desired properties simultaneously.

Inventive Principle:
Principle #40Composite materials

2Reliability

If Al content is increased to improve lithium ion conductivity, then conductivity increases, but mechanical strength decreases

Engineering Contradiction:
Improvelithium ion conductivityVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent optimizes the Al/Si weight ratio parameter to balance conductivity and mechanical strength. By controlling this ratio within 0.61 to 11.9 and achieving 95% or more denseness, the material attains both high lithium ion conductivity and sufficient mechanical strength, resolving the trade-off between these two properties.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite material system with controlled Al and Si content creates a balanced structure where Al enhances lithium ion conductivity while Si and the overall composite structure maintain mechanical integrity. The synergistic combination resolves the contradiction between improving conductivity and preserving mechanical strength.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP2592683B1Solid electrolyte material and lithium battery
Publication Date: 2018.11.14 TOYOTA JIDOSHA KK
  • EP2592683B1 patent drawingFigure 1~2
  • EP2592683B1 patent drawingFigure 3~4

AI summary

A main object of the present invention is to provide a Li-La-Zr-O-based solid electrolyte material having favorable denseness. The present invention solves the problem by providing a solid electrolyte material comprising Li, La, Zr, Al, Si and O, having a garnet structure, and being a sintered body.