Sulfide Solid Electrolyte Composition for High Na+ Conductivity
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Solution Overview
Problem
Current sulfide-based solid electrolytes, such as Na3PS4, have limited room-temperature ionic conductivity, making them unsuitable for widespread use in commercial secondary batteries and other applications requiring efficient ion diffusion at various temperatures.
Innovation Solution
A sulfide-based solid electrolyte composition represented by NaaWbSicSbdSeBrf, where 2.80≤a≤2.89, 0.20≤b≤0.24, 0.08≤c≤0.12, 0.66≤d≤0.70, 3.91≤e≤4, and 0≤f≤0.09, is prepared through mixing raw materials and heating them to a predetermined temperature for a specific duration, resulting in a cubic crystal structure with enhanced ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide solid electrolyte is sintered at high temperature (1200°C to 1600°C) to reduce grain boundary resistance, then room-temperature ionic conductivity increases to levels close to liquid electrolyte, but the processing cost and energy consumption increase significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the solid electrolyte by introducing W and Si elements into the NASICON structure, forming a quaternary compound Na3-x-yWxSiyO2.95. This compositional modification enables the material to achieve high ionic conductivity (close to liquid electrolyte levels) at significantly lower sintering temperatures (900-1100°C), thereby resolving the contradiction between achieving high conductivity and reducing energy consumption.
Solution Approach 2:
The patent creates a composite solid electrolyte system by incorporating multiple elements (Na, W, Si, O) into a unified NASICON-based structure. This composite approach combines the advantages of different elements to achieve synergistic effects, where W and Si doping enhances ionic conductivity while allowing lower processing temperatures, thus resolving the contradiction between performance and energy use.
2Ease of manufacture
If sulfide-based solid electrolyte is used to enable cold-pressing method, then processing cost decreases and ease of manufacture improves, but room-temperature ionic conductivity remains limited compared to liquid electrolyte
Solution Approach 1:
The patent modifies the sulfide-based solid electrolyte composition by introducing W and Si elements into the Na3PS4 structure, forming Na3-x-yWxSiySb1-yO2.95. This compositional parameter change enables the material to maintain the soft, deformable characteristics necessary for cold-pressing while simultaneously achieving high room-temperature ionic conductivity comparable to liquid electrolytes, thus resolving the contradiction between ease of manufacture and reliability.
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 composition exhibits ionic conductivity of 15.0 mS/cm or greater at room temperature and 3.5 mS/cm or greater at −20°C, enabling its use in diverse environments without the need for high-cost processing methods like ball milling or pellet sintering.
Implementation Method 1
A sulfide-based solid electrolyte composition according to the invention exhibits good room-temperature ionic conductivity of 15.0 mS/cm or greater
Implementation Method 2
heating the mixed materials to a predetermined temperature and maintaining the same for a predetermined period of time
Data Source
AI summary
The present invention relates to a solid electrolyte composition and a method for preparing the same. A solid electrolyte composition according to the present invention is characterized by including a material represented by [Formula 1] below.NaaWbSicSbdSeBrf [Equation 1](Here, 2.80≤a≤2.89, 0.20≤b≤0.24, 0.08≤c≤0.12, 0.66≤d≤0.70, 3.91≤e≤4, and 0≤f≤0.09.)