Boron-Doped 3LiOH·Li2SO4 Solid Electrolyte for Conductivity Retention

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Solution Overview

Problem

Existing solid electrolytes, such as those described in Non-Patent Literature 1, do not exhibit sufficient lithium ion conductivity at room temperature and experience a significant decrease in conductivity when held at high temperature for a long time.

Innovation Solution

Incorporating boron into the 3LiOH·Li2SO4 composition to form a solid electrolyte, which is identified by X-ray diffractometry, enhances lithium ion conductivity retention even at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

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

Engineering Contradiction:
Improvelithium ion conductivityVSAvoidconductivity stability at high temperature
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by combining 3LiOH·Li2SO4 with Li3BO3 to create a composite solid electrolyte. This composite structure allows the material to maintain high lithium ion conductivity at room temperature while the Li3BO3 component stabilizes the crystal structure at high temperatures, preventing conductivity degradation. The composite approach resolves the contradiction by integrating two materials with complementary properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the compositional parameters by introducing boron-containing compounds (Li3BO3) into the 3LiOH·Li2SO4 system. By adjusting the ratio of Li3BO3 addition and controlling the sintering temperature parameters, the crystal structure stability is enhanced without significantly compromising room temperature conductivity. This parameter optimization resolves the contradiction between room temperature performance and high temperature stability.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If boron is added to 3LiOH·Li2SO4 to suppress conductivity reduction at high temperature, then the high temperature stability is improved, but the room temperature conductivity may be affected

Engineering Contradiction:
Improveconductivity stability at high temperatureVSAvoidlithium ion conductivity
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent optimizes the compositional parameters by precisely controlling the amount of Li3BO3 added and the sintering temperature. Through parameter optimization, the crystal structure stability is enhanced without significantly compromising room temperature conductivity. This resolves the contradiction by finding the optimal balance point where high temperature stability is improved while maintaining acceptable room temperature performance.

Inventive Principle:
Principle #35Parameter changes

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 addition of boron stabilizes the crystal structure of 3LiOH·Li2SO4, significantly suppressing the reduction in lithium ion conductivity when held at high temperature, maintaining high conductivity over time.

Implementation Method 1

solid electrolytes have been extensively studied and developed in recent years. Particularly, development of the solid electrolytes has been eagerly awaited that can maintain sufficient lithium ion conductivity from room temperature to high temperature

Methodology Applied
Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

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

Methodology Applied
Scientific EffectX-ray diffraction: X-Ray

Data Source

PatentEP3951980B1Solid electrolyte and method for producing solid electrolyte
Publication Date: 2025.11.05 NGK INSULATORS LTD

AI summary

Provided is a 3LiOH·Li2SO4-based solid electrolyte which is capable of significantly suppressing a reduction of the lithium ion conductivity even after being held at high temperature for a long time. This solid electrolyte is identified as 3LiOH·Li2SO4 by diffractometry and further contains boron.