Ge-Substituted LiAsS4 Solid Electrolyte for High Ionic Conductivity

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Solution Overview

Problem

Current solid electrolytes in lithium batteries face limitations due to low ionic conductivity, high activation energy, and interfacial resistance, which hinder their practical application, especially at varying temperatures and compatibility with metallic lithium.

Innovation Solution

A solid electrolyte composed of Li3+xGexAs1-xS4 with x ranging from 0 to 0.50, specifically optimized to have an ionic conductivity greater than 1 mScm−1 at 27°C and activation energy no more than 0.3 eV, achieved through aliovalent substitution of Ge into Li3AsS4, and surface passivation to enhance compatibility with metallic lithium.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If high activation energy solid electrolytes are used, then material processing becomes difficult, but device performance consistency across temperature ranges deteriorates

Engineering Contradiction:

Improvematerial processingVSAvoiddevice performance consistency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent optimizes the compositional parameters (x value in Li3-xGexAs1-xS4) to achieve low activation energy (0.27-0.33 eV). By carefully controlling the Ge substitution level, the material exhibits low activation energy for ionic conduction, which ensures consistent device performance across broad temperature ranges while facilitating easier material processing.

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 solution results in a lithium battery with significantly improved ionic conductivity, low activation energy, and compatibility with metallic lithium, ensuring consistent performance across a broad temperature range and stable lithium cyclability.

Implementation Method 1

The solid electrolyte can have an ionic conductivity of greater than 1 mS cm−1 at 27° C.

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

achieved through aliovalent substitution of Ge into Li3AsS4

Methodology Applied

Scientific EffectAliovalent substitution: Dopants

Implementation Method 3

surface passivation to enhance compatibility with metallic lithium

Methodology Applied

Scientific EffectSurface passivation: Coatings

Data Source

PatentUS10326164B2High-conduction GE substituted LiAsS4 solid electrolyte

Publication Date: 2019.06.18 UT BATTELLE LLC

AI summary

A solid electrolyte for a lithium battery includes Li3+xGexAs1-xS4 where x=0 to 0.50. The value of x can be a range of any high value and any lower value from 0 to 0.50. For example, x can be 0.25 to 0.50, and x can be 0.3 to 0.4, among many other possible ranges. In one embodiment x=0.33 such that the solid electrolyte is Li3.334Ge0.334As0.666S4. A solid electrolyte for a lithium battery can include LiAsS4 wherein ½ to ⅔ of the As is substituted with Ge. A lithium battery and a method for making a lithium battery are also disclosed.