Boron-Containing 3LiOH·Li2SO4 Solid Electrolyte for Heat Stability

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Solution Overview

Problem

The existing solid electrolyte described in Non-Patent Literature 1 does not have sufficiently high lithium ion conductivity at room temperature and exhibits reduced conductivity when held at high temperature for a long time.

Innovation Solution

A solid electrolyte identified as 3LiOH·Li2SO4 by X-ray diffractometry, further comprising boron, which is added to suppress the reduction of lithium ion conductivity even after being held at high temperature for a long time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a solid electrolyte with composition 3LiOH·Li2SO4 is used, then high lithium ion conductivity at room temperature is achieved, but lithium ion conductivity decreases when held at high temperature for a long time

Engineering Contradiction:
Improvelithium ion conductivity retention at high temperatureVSAvoidstability after long-term high temperature holding
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention creates a composite solid electrolyte system by combining 3LiOH·Li2SO4 with boron-containing compounds (Li3BO3, B2O3, or H3BO3). This composite approach allows the base 3LiOH·Li2SO4 to provide high room temperature conductivity while the boron component stabilizes the structure during long-term high temperature exposure, preventing conductivity degradation.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention modifies the chemical composition parameters of the solid electrolyte by introducing boron in controlled amounts (0.01-5 mol% relative to total lithium content). This parameter change transforms the material properties, enabling the electrolyte to maintain structural stability and conductivity at elevated temperatures without sacrificing room temperature performance.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If boron is added to 3LiOH·Li2SO4 solid electrolyte, then lithium ion conductivity retention at high temperature is improved, but manufacturing process complexity increases

Engineering Contradiction:
Improvelithium ion conductivity retention at high temperatureVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention incorporates boron-containing compounds into the raw material mixture before the melting and solidification process. This preliminary incorporation ensures uniform distribution of boron throughout the solid electrolyte structure, achieving the desired stability improvement without requiring complex post-processing steps or additional manufacturing complexity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention merges the synthesis of 3LiOH·Li2SO4 with the incorporation of boron-containing compounds into a single manufacturing process. By combining these steps, the invention achieves the dual benefit of high room temperature conductivity and improved high temperature stability while maintaining a relatively simple and integrated manufacturing workflow.

Inventive Principle:
Principle #5Merging (Combining)

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

The inclusion of boron in the 3LiOH·Li2SO4-based solid electrolyte significantly improves the retention of lithium ion conductivity at high temperatures, making it suitable for use in electric storage devices such as lithium ion secondary batteries.

Implementation Method 1

the solid electrolyte is identified as 3LiOH·Li2SO4 by X-ray diffractometry

Methodology Applied
Scientific EffectX-ray diffraction: X-Ray

Implementation Method 2

melting and then cooling a raw material including LiOH, Li2SO4 and Li3BO3 to form a solidified body

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentUS12237465B2Solid electrolyte and method for producing solid electrolyte
Publication Date: 2025.02.25 NGK INSULATORS LTD

AI summary

Provided is a solid electrolyte which is identified as 3LiOH·Li2SO4 by diffractometry. The solid electrolyte further contains boron.