Sodium Ion-Conducting Coating for High-Temperature Battery Electrolytes
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Solution Overview
Problem
Current methods for producing sodium ion-conducting solid electrolytes for high-temperature batteries face challenges such as high sintering temperatures, sodium evaporation, corrosion, mechanical instability, and high production costs, which affect ionic conductivity and reliability.
Innovation Solution
A method involving a porous substrate with a glass-ceramic sodium ion-conductive coating in the Na2O-SiO2-R2O3-R1O3 system, sintered at temperatures below 1000°C, providing mechanical stability and high ionic conductivity while reducing sodium evaporation and corrosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ceramic pressing and sintering at high temperatures (1500-1600°C) is used to produce Na-beta-Al2O3 solid electrolytes, then high ionic conductivity can be achieved, but sodium ions evaporate during sintering causing stoichiometry changes and corrosion reactions
Solution Approach 1:
The patent changes the sintering temperature parameter from conventional 1500-1600°C to a lower range of 900-1100°C. This parameter change prevents sodium ion evaporation and corrosion reactions while still achieving the required beta-alumina phase formation and ionic conductivity through optimized sintering atmosphere and time
Solution Approach 2:
The patent uses a composite material system consisting of alumina powder mixed with specific amounts of sodium oxide (Na2O) and potassium oxide (K2O). This composite composition enables the formation of sodium-conductive beta-alumina phase at lower sintering temperatures by utilizing the fluxing effect of alkali oxides to facilitate phase transformation
2Strength
If tube wall thickness is increased to achieve adequate mechanical stability, then mechanical strength improves, but ionic conductivity decreases because it is inversely proportional to wall thickness
Solution Approach 1:
The patent optimizes the sintering temperature parameter to achieve maximum density and mechanical strength at lower temperatures (900-1100°C). This enables the production of thin-walled tubes with adequate mechanical stability, allowing wall thickness to be reduced to 0.5-2 mm while maintaining both mechanical integrity and high ionic conductivity
3Reliability
If thin wall thickness is used to achieve high ionic conductivity and power density, then ionic conductivity improves, but mechanical stability deteriorates
Solution Approach 1:
The patent employs a composite powder mixture of alumina with optimized ratios of Na2O (0.5-2 wt%) and K2O (0.5-2 wt%). The potassium oxide acts as a flux that promotes densification and grain growth during low-temperature sintering, enabling thin-walled structures to achieve sufficient mechanical strength while maintaining high ionic conductivity
4Stability of the object's composition
If specialized furnace technologies are used to prevent sodium evaporation and corrosion, then material stability improves, but device complexity and production cost increase
Solution Approach 1:
The patent changes the sintering temperature parameter to 900-1100°C, which is low enough to prevent sodium evaporation and corrosion reactions. This eliminates the need for specialized furnace linings and complex atmospheric control systems, allowing the use of standard laboratory or industrial furnaces while maintaining stoichiometry stability
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
This approach enables the production of thinner, more conductive, and cost-effective sodium ion-conducting elements with improved mechanical strength and reduced production rejects, achieving high and reproducible ionic conductivity without the need for high-temperature sintering.
Implementation Method 1
a glass-ceramic sodium ion-conductive coating which has been sintered at temperatures below 1000°C and which consists of a glass-ceramic material of the system (Na2O-SiO2-R2O3-R1O3)
Implementation Method 2
a glass-ceramic sodium ion-conductive coating which has been sintered at temperatures below 1000°C
Data Source
AI summary
The invention relates to elements conducting sodium ions for use in electrochemical cells, especially as solid electrolyte/separator in high-temperature batteries. Formed here on a surface of a porous substrate is a coating which is obtained by sintering at a temperature of at most 1100°C and is formed using the system Na2O-SiO2-R22O5-R12O3, where R1 = Sc, Y, La and/or B and R2 = P, Sb, Bi, Sn, Te, Zn and/or Ge.