Solid Lithium Electrolyte Composition Stable Against Lithium Metal
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Solution Overview
Problem
There is a need for lithium conductors with high ionic conductivity and electrochemical stability for use as solid electrolytes in all-solid state lithium batteries, particularly in direct contact with lithium metal.
Innovation Solution
Development of solid materials with compositions according to formula Li7+x−yMxSb1−xS8−yXy, where M is Si, Ge, or Sn, and X is Cl, Br, or I, exhibiting favorable lithium ion conductivity and electrochemical stability, prepared through a process involving precursors like Li2S, Sb2S3, LiX, and elemental S, heat-treated at specific temperatures and durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid electrolytes like Li6PS5I are used, then ionic conductivity can be achieved (about 7*10−3 S/cm), but electrochemical stability in direct contact with lithium metal is insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the solid electrolyte by incorporating elements from groups 13-16 (B, Si, Ge, Sn, Pb) and group 15 (N, P, As, Sb, Bi) into the argyrodite structure. This compositional parameter change enables the material to simultaneously achieve high ionic conductivity (≥10^-3 S/cm) and electrochemical stability against lithium metal, eliminating the need for protective layers.
Solution Approach 2:
The patent creates composite solid electrolyte materials by combining lithium argyrodite base structure with additional elements (B, Si, Ge, Sn, Pb, N, P, As, Sb, Bi) in specific ratios. This composite approach allows the material to integrate multiple functions: maintaining the argyrodite's inherent ionic conductivity while adding electrochemical stability through the incorporated elements, thereby resolving the contradiction between conductivity and stability.
2Reliability
If lithium argyrodites are used as solid electrolytes, then high ionic conductivity can be achieved (up to 18.4±2.7 mS/cm), but electrochemical stability in direct contact with lithium metal remains insufficient
Solution Approach 1:
The patent optimizes compositional parameters within the formula Li6+xMyP1-xS5I where M represents elements from groups 13-16 and group 15. By carefully controlling the substitution ratios (x values) and selecting specific element combinations, the patent achieves both high ionic conductivity and electrochemical stability while maintaining a relatively simple solid-state reaction manufacturing process.
Solution Approach 2:
The patent introduces specific elements at targeted positions within the crystal structure to locally enhance electrochemical stability. The substitution of P with elements from groups 13-16 and group 15 creates local structural modifications that improve stability against lithium metal while preserving the overall argyrodite framework's ionic conductivity pathways.
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 materials achieve ionic conductivities of 0.1 mS/cm or more and electrochemical stability in direct contact with lithium metal for over 1,000 hours, reducing the complexity of electrochemical cell configurations by eliminating the need for a protection layer between lithium metal and the solid electrolyte.
Implementation Method 1
a solid material which has ionic conductivity for lithium ions
Implementation Method 2
heat-treated at specific temperatures and durations
Data Source
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.