LGPS Sulfide Solid Electrolyte Composition With Reduced Impurity Phases
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Solution Overview
Problem
Sulfide solid electrolytes with LGPS-type crystal phase often include impurity components that reduce ion conductivity, limiting their performance in all-solid-state batteries.
Innovation Solution
A sulfide solid electrolyte with a composition of Li4-xSn1-xPxS4, where 0.67<x<0.76, featuring specific peak positions in 31P-NMR measurements and optimized peak ratios to enhance ion conductivity, is developed by heating an amorphized ion conductive material in an inert gas flow to minimize impurity components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide solid electrolytes with LGPS-type crystal phase are produced using conventional methods, then the crystal phase structure is formed, but impurity components are generated that reduce ion conductivity
Solution Approach 1:
The patent applies preliminary action by amorphizing the raw material composition before crystallization. The amorphized state serves as a precursor that, when subsequently crystallized under controlled conditions, produces the desired LGPS-type crystal phase with minimal impurities. This preliminary amorphization step prepares the material in a state that facilitates cleaner phase transformation and reduces impurity formation during crystallization.
Solution Approach 2:
The patent employs an inert atmosphere (argon or nitrogen) during the heating and crystallization process to prevent oxidation and contamination of the sulfide solid electrolyte. This inert environment protects the sensitive sulfide materials from reacting with atmospheric oxygen, thereby minimizing the formation of oxide impurities that would otherwise degrade ion conductivity.
2Reliability
If the composition ratio of Li, Sn, P, and S is adjusted to optimize ion conductivity, then high conductivity can be achieved, but precise control of phase purity becomes more difficult
Solution Approach 1:
The patent utilizes parameter changes by systematically varying the composition ratio (specifically x in Li4-xSn1-xPxS4 where 0.67<x<0.76) and heating temperature to optimize both ion conductivity and phase purity. By adjusting these parameters within specific ranges, the patent achieves a balance where the desired LGPS-type phase forms with high purity while maintaining superior ion conductivity exceeding 5.25 mS/cm at 25°C.
Solution Approach 2:
The patent employs feedback through characterization techniques (XRD and 31P-NMR) to monitor the crystal phase structure and composition. This feedback information is used to verify the formation of the desired LGPS-type phase and detect any impurity phases, allowing for optimization of synthesis conditions to achieve both high phase purity and high ion conductivity simultaneously.
3Reliability
If amorphized ion conductive material is heated to crystallize the LGPS-type phase, then high ion conductivity is achieved, but impurity phases may form during the heating process
Solution Approach 1:
The patent employs an inert atmosphere (argon or nitrogen) during the heating and crystallization process to prevent oxidation and contamination of the sulfide solid electrolyte. This inert environment protects the sensitive sulfide materials from reacting with atmospheric oxygen, thereby minimizing the formation of oxide impurities that would otherwise degrade ion conductivity.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the composition ratio (specifically x in Li4-xSn1-xPxS4 where 0.67<x<0.76) and heating temperature to optimize both ion conductivity and phase purity. By adjusting these parameters within specific ranges, the patent achieves a balance where the desired LGPS-type phase forms with high purity while maintaining superior ion conductivity exceeding 5.25 mS/cm at 25°C.
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 resulting sulfide solid electrolyte achieves high ion conductivity, exceeding 5.25 mS/cm at 25°C, and is used to improve discharge properties in batteries.
Implementation Method 1
heating an amorphized ion conductive material in an inert gas flow
Implementation Method 2
A sulfide solid electrolyte including a LGPS-type crystal phase... is developed by heating an amorphized ion conductive material
Implementation Method 3
specific peak positions in 31P-NMR measurements and optimized peak ratios
Data Source
AI summary
A main object of the present disclosure is to provide a sulfide solid electrolyte with high ion conductivity. The present disclosure achieves the object by providing a sulfide solid electrolyte including a LGPS-type crystal phase containing a Li element, a Sn element, a P element, and a S element, wherein: the sulfide solid electrolyte has a composition represented by Li4−xSn1−xPxS4, provided that 0.67<x<0.76; the sulfide solid electrolyte includes, in a 31P-NMR measurement, a first peak of which peak position is 77 ppm±1 ppm, and a second peak of which peak position is 93 ppm±1 ppm; and when S1 designates a total area of all peaks obtained in the 31P-NMR measurement, and S2 designates a total area of the first peak and the second peak, a rate of S2 with respect to S1, which is S2/S1 is 92.0% or more.