Solid Sodium-Ion Electrolyte Composition for Low-Volatility Conductivity
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Solution Overview
Problem
Current sodium-based electrolyte compositions for electrochemical cells face challenges due to flammability and high volatility, limiting their commercial applicability and requiring operation at high temperatures, which restricts their use to industrial applications.
Innovation Solution
A sodium-ion electrolyte composition comprising a mixture of a phosphonium salt and a sodium salt, which presents as a solid up to at least 25°C, offering high ionic conductivity and reduced volatility, allowing for operation at lower temperatures and wider temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid electrolyte compositions are used, then high ionic conductivity is achieved, but flammability and high volatility occur
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid by using a eutectic mixture of phosphonium salt and sodium salt, which presents as a solid up to at least 25°C. This phase change eliminates flammability and volatility while maintaining high ionic conductivity through the solid-state ionic conduction mechanism
Solution Approach 2:
The patent employs a composite electrolyte system consisting of a eutectic mixture between phosphonium salt (e.g., trimethyl-isobutyl-phosphonium bis(trifluoromethylsulfonyl)imide) and sodium salt (e.g., sodium bis(trifluoromethylsulfonyl)imide). This composite approach combines the advantages of both components to achieve solid-state structure with high ionic conductivity, resolving the contradiction between conductivity and safety
2Object-affected harmful factors
If solid state ceramic electrolyte is used, then low volatility and improved safety are achieved, but high operating temperature (~300°C) is required
Solution Approach 1:
The patent modifies the operating temperature parameter by developing a solid electrolyte composition that maintains high ionic conductivity at room temperature (up to at least 25°C) rather than requiring high temperatures. The eutectic mixture achieves this through its specific phase behavior and ionic conduction mechanism in the solid state
Solution Approach 2:
The patent utilizes phase transition properties by designing an electrolyte composition that presents as a solid up to at least 25°C through eutectic formation. This phase behavior allows the material to maintain solid-state safety characteristics while enabling ionic conduction at lower temperatures compared to conventional ceramic electrolytes
3Reliability
If solid state electrolyte is used, then improved safety is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent exploits the eutectic composition parameter to create a robust solid electrolyte system. The eutectic mixture maintains its solid-state properties and high ionic conductivity over a wide concentration range of sodium salt, providing manufacturing tolerance and reducing precision requirements compared to stoichiometrically-sensitive solid-state electrolytes
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 electrolyte composition enables electrochemical cells to sustain high current densities at room temperature, extending their application into wider commercial uses with improved safety and manufacturing ease, while maintaining high ionic conductivity and stability.
Implementation Method 1
Being electronically insulating but ionically conductive, electrolyte compositions facilitate the exclusive transfer of positive charges between electrodes by providing a separate and isolated pathway to cations relative to electrons
Data Source
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Figure 3(a)~3(g)
AI summary
A sodium-ion electrolyte composition for use in an electrochemical cell, the electrolyte composition comprising a mixture of a phosphonium salt and a sodium salt, wherein the electrolyte composition presents as a solid up to at least 25°C.