Lithium Argyrodite Solid Electrolyte with Vacancy-Driven Ion Conduction
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Solution Overview
Problem
There is a need for lithium ion conductors with improved ionic conductivity and electrochemical stability for use as solid electrolytes in all-solid state lithium batteries, as existing lithium argyrodites have limitations in conductivity and stability.
Innovation Solution
A solid material with a composition of Li6+2*n-x-m*y M y PS 5+n-x X 1+x, where M is divalent metals like Mg, Ca, Sr, Ba, and Zn, or trivalent metals like Sc, La, Al, and Ga, and X is F, Cl, Br, or I, is developed, which exhibits favorable lithium ion conductivity and stability by generating lithium vacancies, increasing mobility and diffusivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium argyrodites are used as solid electrolytes, then ionic conductivity can be improved, but electrochemical stability versus lithium metal deteriorates
Solution Approach 1:
The patent applies parameter changes by systematically modifying the chemical composition parameters of lithium argyrodites through partial substitution of lithium ions with divalent (Mg, Ca, Sr, Ba, Zn) and trivalent (Sc, La, Al, Ga) metals. This substitution strategy changes the stoichiometric parameters to create lithium vacancies while maintaining the overall argyrodite structure, thereby improving ionic conductivity without sacrificing electrochemical stability.
Solution Approach 2:
The patent creates composite materials by combining lithium argyrodite base structure with substituted metal ions. The resulting material is a composite solid electrolyte that integrates the high ionic conductivity of lithium argyrodites with the stabilizing effect of substituted metals, achieving both improved conductivity and maintained electrochemical stability versus lithium metal.
2Reliability
If partial substitution of lithium by other metals is performed, then ionic conductivity and chemical stability can be improved, but structural complexity increases
Solution Approach 1:
The patent applies local quality by introducing metal substitutions at specific lattice positions within the argyrodite structure. The substituted metals (Mg, Ca, Sr, Ba, Zn, Sc, La, Al, Ga) occupy lithium sites locally, creating lithium vacancies in specific regions while preserving the overall crystal structure. This localized substitution approach improves chemical stability without requiring complete structural redesign.
3Reliability
If lithium vacancies are generated to increase mobility and diffusivity, then ionic conductivity improves, but material composition stability deteriorates
Solution Approach 1:
The patent carefully controls the substitution parameter x in the composition formula Li6+2x-yMxPS5-xX1+x, where M represents substituted metals. By limiting x to 0.01 ≤ x ≤ 0.25, the patent generates sufficient lithium vacancies to improve ionic conductivity while maintaining composition stability. The halide substitution parameter is also controlled at 0.15 ≤ x ≤ 0.6 to balance vacancy creation with structural integrity.
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 solid material achieves high ionic conductivity of 1 mS/cm or more at 25°C with negligible electronic conductivity, suitable for use as a solid electrolyte in electrochemical cells, enhancing the performance of all-solid state lithium batteries.
Implementation Method 1
due to the presence of the divalent resp. trivalent metal M in the solid material having a composition according to general formula (I) lithium vacancies are generated which results in an increase of the mobility and diffusivity of lithium ions
Data Source
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AI summary
Described are a solid material which has ionic conductivity for lithium ions, a process for preparing said solid material, a use of said solid material as a solid electrolyte for an electrochemical cell, a solid structure selected from the group consisting of a cathode, an anode and a separator for an electrochemical cell comprising the solid material, and an electrochemical cell comprising such solid structure.