Sulfide Solid-State Electrolyte Composition for Sodium-Ion Conductivity
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Solution Overview
Problem
Current solid-state electrolytes for sodium-ion batteries have limited ionic conductivity, specifically below 0.30 mS/cm at 30°C and 0.90 mS/cm at 60°C, which hinders the performance of solid-state rechargeable sodium-ion batteries.
Innovation Solution
A solid-state electrolyte composition comprising Na, Sn, and As with specific molar ratios (3.50≤x≤4.00, 0.50≤y≤1.00, and 0.00<z≤0.50) and a manufacturing process involving mixing Na2S, SnS2, As2S3, and S powders, pressing, and firing at controlled temperatures to achieve enhanced ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid-state electrolyte compositions (e.g., Na4-xSn1-xSbxS4) are used, then the electrolyte structure is stable, but the ionic conductivity remains limited (maximum 0.30 mS/cm at 30°C)
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar ratios of Na, Sn, and As within specific ranges (Na: 3.50-4.00, Sn: 0.50-1.00, As: 0.00-0.50) to optimize ionic conductivity. This systematic variation of compositional parameters enables achieving conductivity of at least 0.10 mS/cm at 30°C, resolving the contradiction between maintaining structural stability and improving ionic conductivity.
Solution Approach 2:
The patent employs composite materials by combining Na, Sn, and As elements in a multi-element solid-state electrolyte system (NaxSnyAszS4). This composite approach leverages the synergistic effects of different elements to achieve superior ionic conductivity compared to conventional single-element or binary systems, while maintaining structural stability through the balanced composition.
2Productivity
If higher ionic conductivity is achieved through composition optimization, then battery performance improves, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-mixing the Na2S, SnS2, and As2S3 powders in precise molar ratios before the firing process. This preliminary preparation of the composite powder mixture ensures that the subsequent sintering process produces a homogeneous electrolyte with optimized ionic conductivity, thereby improving battery operational efficiency while keeping the manufacturing process manageable.
3Temperature
If conventional electrolytes are used, then the manufacturing process is simpler, but the temperature requirements for optimal performance are higher
Solution Approach 1:
The patent utilizes parameter changes in the compositional parameters (Na, Sn, As ratios) to lower the operational temperature requirement. By optimizing the molar contents within the specified ranges, the electrolyte achieves sufficient ionic conductivity (at least 0.10 mS/cm) at 30°C, thereby reducing the temperature requirement for optimal battery performance while maintaining reliable ionic conductivity.
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 proposed electrolyte achieves ionic conductivity of at least 0.10 mS/cm at 30°C and over 1.00 mS/cm at 60°C, significantly improving the performance of solid-state rechargeable sodium-ion batteries by increasing operational efficiency and reducing temperature requirements.
Implementation Method 1
a high ionic conductivity (e.g. of at least 0.10 mS/cm) of a solid-state electrolyte is achieved
Data Source
AI summary
The present invention provides a solid-state electrolyte for solid-state rechargeable sodium-ions batteries comprising: —Na in a molar content x of at least 3.50 and of at most 4.00, —Sn in a molar content y of at least 0.50 and of at most 1.00, —As in a molar content z superior to 0.00, preferably of at least 0.10, and of at most 0.50, —S in a molar content of 4.00.