Sulfide Solid Electrolyte Sn-Si Composition
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Solution Overview
Problem
Current lithium batteries with sulfide solid electrolytes face challenges due to the high cost and low chemical stability of Ge, which leads to reductive decomposition when used with negative electrodes having potentials below 0.25 V, limiting their electrochemical performance.
Innovation Solution
Replacing Ge with Sn and Si in the LGPS-based sulfide solid electrolyte system to create a solid conductive material with the composition formula Li4-x[Sn y Si (1-y)] (1-x) P x S4, achieving high ionic conductivity and improved electrochemical stability by maintaining an LGPS-type crystal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ge is used in LGPS-based sulfide solid electrolyte to achieve high ionic conductivity, then ionic conductivity is improved, but cost increases and electrochemical stability deteriorates due to reductive decomposition
Solution Approach 1:
The patent changes the chemical composition parameters by replacing Ge with Sn and Si in specific ratios (0.1 ≤ y ≤ 0.9 where y is the Sn mole fraction). This parameter change maintains the LGPS-type crystal structure while achieving both high ionic conductivity (≥10^-3 S/cm at 25°C) and improved electrochemical stability by eliminating Ge-induced reductive decomposition
Solution Approach 2:
The patent replaces expensive Ge with cheaper Sn and Si elements, significantly reducing material cost while maintaining or improving performance. The use of abundant Sn-Si solid solution components eliminates reliance on costly and electrochemically unstable Ge
2Reliability
If Ge is used in LGPS-based sulfide solid electrolyte to achieve high ionic conductivity, then ionic conductivity is improved, but manufacturing cost increases
Solution Approach 1:
The patent substitutes expensive Ge with cost-effective Sn and Si elements, reducing raw material costs. The Sn-Si solid solution uses abundant, inexpensive elements while achieving comparable or superior ionic conductivity to Ge-based LGPS materials
Solution Approach 2:
The patent optimizes composition parameters (x, y ranges) to achieve high ionic conductivity without Ge, enabling cost-effective manufacturing while meeting performance requirements for solid-state batteries
3Object-generated harmful factors
If Ge-free Sn-Si solid solution is used to improve electrochemical stability, then electrochemical stability is improved, but ionic conductivity may deteriorate
Solution Approach 1:
The patent precisely controls composition parameters (0.1 ≤ x ≤ 0.7 for P content, 0.1 ≤ y ≤ 0.9 for Sn mole fraction) to simultaneously achieve high ionic conductivity (≥10^-3 S/cm) and electrochemical stability. The optimized Sn-Si-P solid solution maintains the critical LGPS-type crystal structure with conducting channels
Solution Approach 2:
The patent creates a composite Sn-Si-P solid solution system that combines the advantages of Sn and Si elements within an LGPS-type structure, achieving both high ionic conductivity and electrochemical stability that neither element alone could provide
Data Source
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AI summary
To provide a sulfide solid electrolyte material which does not include Ge and which has excellent electrochemical stability and high lithium ion conductivity. A sulfide solid electrolyte, including a sulfide-based solid electrolyte represented by the composition formula: Li4-4z-x[SnySi1-y]1+z-xPxS4 (where 0.5 ≤ x ≤ 0.6, y = 0.2, and 0 ≥ z ≥ -0.2), wherein the sulfide solid electrolyte has a peak at position 2θ = 29.58° ± 0.50° in X-ray diffraction measurement using CuKα radiation and does not have a peak at position 2θ = 27.33° ± 0.50° in X-ray diffraction measurement using CuKα radiation, or when the sulfide solid electrolyte has a peak at the position 2θ = 27.33° ± 0.50°, the value of IB/IA is less than 0.50 (where IA is the diffraction intensity of the 2θ = 29.58° ± 0.50° peak and IB is the diffraction intensity of the 2θ = 27.33° ± 0.50° peak).