Doped Cubic Bismuth Oxide Electrolyte for Stable 650°C Conductivity
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Solution Overview
Problem
Current solid oxide cell (SOC) technologies face challenges due to the high temperatures required for sufficient oxygen-ion conductivity, which limits their application and increases manufacturing costs. Additionally, existing doped cubic bismuth oxide electrolytes are not phase stable below 600°C, leading to a significant drop in conductivity.
Innovation Solution
A doped cubic bismuth oxide composition is developed, which is phase stable in the temperature range of 550°C to 700°C and exhibits higher conductivity than Bi1.76Dy0.16W0.08O3 (DWSB) at 650°C. This is achieved by using a mixture of specific dopants, such as La and Zr, in concentrations of 10 mole % or less, which stabilizes the cubic phase and enhances oxygen-ion mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional zirconia-based electrolytes are used in SOFCs/SOECs, then the materials have good stability, but the oxygen-ion conductivity is insufficient below 700°C requiring high operating temperatures (≥800°C)
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by doping bismuth oxide with specific ratios of rare earth elements (lanthanum, cerium, praseodymium, neodymium, or samarium) to transform the material properties, enabling high ionic conductivity at lower temperatures while maintaining stability
Solution Approach 2:
The patent creates a composite electrolyte material by combining doped bismuth oxide with stabilizing rare earth oxides, forming a new composite system (Bi2-x-yRaxCyO3-δ) that exhibits both high ionic conductivity and thermal stability at reduced operating temperatures
2Reliability
If doped cubic bismuth oxide is used to achieve high conductivity, then the oxygen-ion conductivity improves, but the phase stability is lost below 600°C causing significant conductivity drop
Solution Approach 1:
The patent modifies the compositional parameters by introducing multiple rare earth dopants at controlled concentrations (x+y=0.1 to 0.5) to stabilize the cubic phase structure at lower temperatures, preventing the phase transition that would otherwise cause conductivity loss below 600°C
Solution Approach 2:
The patent develops a composite doped bismuth oxide system where rare earth elements (Ra and Rb) are incorporated into the bismuth oxide lattice, creating a composite structure that maintains cubic phase stability and high ionic conductivity across a broader temperature range including below 600°C
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 doped cubic bismuth oxide electrolyte maintains high conductivity and stability at 650°C for at least 100 hours, with conductivity values exceeding DWSB by up to 30%. This allows for the potential reduction of operational temperatures in SOC technologies, improving efficiency and reducing costs.
Implementation Method 1
a doped cubic bismuth oxide composition that is phase stable in a temperature range of from about 550° C. to about 700° C.
Implementation Method 2
exhibits higher conductivity than Bi1.76Dy0.16W0.08O3 (DWSB) at 650° C.
Implementation Method 3
achieved by using a mixture of specific dopants, such as La and Zr, in concentrations of 10 mole % or less
Data Source
AI summary
The present invention relates to a doped cubic bismuth oxide that is phase stable in a temperature range of from about 550° C. to about 700° C. The doped cubic bismuth oxide comprises a mixture of a first dopant and a second dopant.