Sulfide Solid Electrolyte Composition for Higher Li-Ion Conductivity
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Solution Overview
Problem
The ion conductivity of Li4PS4I, a candidate sulfide-based solid electrolyte for all-solid-state batteries, is one to two orders of magnitude lower than other materials, hindering its application in high-energy density batteries.
Innovation Solution
A sulfide-based solid electrolyte composition of Li4P1-xSixS4-xHaxI, where Si replaces P and one or two of Cl, Br, and I replace S, expanding the crystal lattice and enhancing ion conductivity while maintaining structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li4PS4I is used as a solid electrolyte, then electrochemical stability and low H2S generation are achieved, but ion conductivity is one to two orders of magnitude lower than other sulfide-based materials
Solution Approach 1:
The patent applies parameter changes by systematically varying the composition parameters x and y in the formula Li4P1-xSixS4-xHaxI to optimize ion conductivity. By changing the substitution ratios of Si for P and halogen atoms for S, the patent achieves a balance between maintaining electrochemical stability and improving ion conductivity to exceed 10^-3 S/cm at room temperature.
Solution Approach 2:
The patent creates a composite solid electrolyte material by combining multiple elements (Li, P, Si, S, and halogen atoms) in a specific compositional framework. This composite approach allows the material to inherit electrochemical stability from the base Li4PS4I structure while gaining enhanced ion conductivity through controlled substitution of Si and halogen atoms.
2Object-generated harmful factors
If Si substitutes for P and halogen atoms substitute for S in Li4PS4I, then ion conductivity increases up to 10 times, but crystal structure stability must be maintained
Solution Approach 1:
The patent systematically varies the substitution parameters x and y within specific ranges (0 < x ≤ 0.5 and 0 < y ≤ 1.0) to optimize the balance between ion conductivity and structural stability. This controlled parameter adjustment allows the crystal structure to adapt to the substitutions while maintaining its fundamental stability and tetragonal space group P4/nmm.
Solution Approach 2:
The patent applies local quality by introducing Si and halogen atoms at specific substitutional positions within the crystal lattice. This localized substitution approach allows specific regions of the crystal structure to be modified for enhanced ion conductivity while preserving the overall structural framework and stability of the material.
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 modified electrolyte achieves ionic conductivity up to 10 times higher than conventional Li4PS4I, improving battery capacity and performance, particularly in high-rate applications.
Implementation Method 1
Si replaces P and one or two of Cl, Br, and I replace S, expanding the crystal lattice and enhancing ion conductivity
Data Source
AI summary
A sulfide-based solid electrolyte represented by the formula Li4P1-xSixS4-xHaxI (wherein Ha is one or both of Cl, Br and I, and 0.05<x≤0.3).