Sulfide Solid Electrolyte Composition for Stable High Li-Ion Phases
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Solution Overview
Problem
Existing methods for producing sulfide solid electrolytes face issues such as nitrogen discharge to the outside of the system, low thermal stability, and limited temperature range for high Li-ion conductivity phases, which affect the performance and stability of all-solid-state batteries.
Innovation Solution
A method involving the use of specific raw material compounds containing N, an element A, and an element M, selected based on high defect generation energy, to suppress nitrogen discharge and enhance thermal stability, including a composition preparation, reaction, and heat treatment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li3N is used as a raw material for sulfide solid electrolyte, then atmospheric stability (water resistance) is improved, but nitrogen is discharged to the outside of the system
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific elements (Al, Ta, Si, Sc, Mg, Nb, B, Hf, C, P, Zr, or Ti) to form new compounds that suppress nitrogen discharge while maintaining atmospheric stability. This modifies the raw material system from simple Li3N to composite sulfide solid electrolytes with enhanced properties.
Solution Approach 2:
The patent creates composite sulfide solid electrolyte materials by combining multiple elements (Li, P, S, N, and additional elements like Al, Ta, Si, etc.) to form new compound systems. These composite materials simultaneously achieve atmospheric stability and suppress nitrogen discharge through synergistic effects of the constituent elements.
2Reliability
If excessively high heat treatment temperature is used to precipitate high Li-ion conductive phase, then Li-ion conductivity is improved, but low Li-ion conductive phase is also precipitated
Solution Approach 1:
The patent optimizes the heat treatment temperature parameter based on the specific composition of the sulfide solid electrolyte. By adjusting the temperature within a controlled range and using compositional modifications (adding elements like Al, Ta, Si, etc.), the patent achieves selective precipitation of high Li-ion conductive phases while suppressing the formation of low conductive phases.
Solution Approach 2:
The patent creates local compositional variations by introducing specific elements that preferentially stabilize certain phases. These elements create local regions with different properties, allowing high Li-ion conductive phases to form selectively while preventing the formation of low conductive phases even at elevated temperatures.
3Stability of the object's composition
If Li3N is added to increase the temperature difference between high and low Li-ion conductive phase formation, then phase stability is improved, but the temperature difference is limited to approximately 30°C
Solution Approach 1:
The patent develops composite sulfide solid electrolyte systems that combine multiple elements (Li, P, S, N with additional elements) to create new phase formation mechanisms. These composite materials achieve larger temperature differences between phase transitions, expanding the stable temperature range beyond the limited 30°C achieved with Li3N alone.
Solution Approach 2:
The patent modifies the compositional parameters by introducing elements that significantly alter the phase diagram and phase transition temperatures. This creates a broader temperature window for stable high Li-ion conductive phases, enhancing both phase stability and temperature range adaptability.
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 method effectively suppresses nitrogen discharge, enhances thermal stability, and expands the temperature range for high Li-ion conductivity phases, improving the performance and stability of sulfide solid electrolytes and all-solid-state batteries.
Implementation Method 1
a raw material composition containing Li2S, P2S5, LiI, and LiBr is made amorphous
Implementation Method 2
subjected to a heat treatment to precipitate a high Li-ion conductive phase
Implementation Method 3
heating the intermediate to obtain a sulfide solid electrolyte
Data Source
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AI summary
The present invention relates to a crystalline sulfide solid electrolyte comprising P, S, N, an element A, an element X, and an element M, and having crystallinity (A represents at least one element selected from the group consisting of Li, Na, and K; X represents at least one element selected from the group consisting of Cl, Br, and I; M represents at least one element selected from the group consisting of Al, Ta, Si, Sc, Mg, Nb, B, Hf, C, Zr, and Ti), wherein the crystalline structure has diffraction peaks at 2θ = 20.2° ± 0.5° and 23.6° ± 0.5° in X-ray diffraction measurement with a CuKα line.