Core-Shell Ni Electrode Composition for SOEC Steam Durability
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Solution Overview
Problem
The electrolytic properties of Ni/YSZ fuel electrodes in SOEC degrade over time due to morphological changes caused by gas-phase diffusion of Ni when exposed to high-temperature steam, leading to decreased efficiency.
Innovation Solution
The use of electrolyte particles composed of Gd-doped CeO2 (GDC) and/or Gd- and La-doped CeO2 (La-GDC) with Ni-based core-shell particles, where the core is covered by a composite oxide shell containing NiO or Ni, to suppress gas-phase diffusion and maintain electrode performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ni/YSZ fuel electrodes are used in SOEC, then initial electrolytic properties are good, but degradation occurs over time due to gas-phase diffusion of Ni
Solution Approach 1:
A shell layer comprising NiO and/or Ni is formed on the surface of the Ni-based particles. This shell acts as a protective barrier that suppresses gas-phase diffusion of Ni while maintaining the electrocatalytic activity of the core particles, thereby preventing morphological changes and degradation over time
Solution Approach 2:
The electrode uses composite Ni-based core-shell particles where a Ni or Ni-based alloy core is surrounded by a shell of NiO and/or Ni. This composite structure combines the high electrocatalytic activity of metallic Ni with the protective and structurally stable oxide shell, resolving the contradiction between initial performance and long-term stability
2Productivity
If high-temperature steam exposure is used for electrolysis, then electrolytic efficiency is high, but Ni gas-phase diffusion increases causing degradation
Solution Approach 1:
The NiO/Ni shell layer serves as a thermal and chemical barrier that protects the core particles from high-temperature steam environments. The shell maintains structural integrity at high temperatures while allowing ionic and electronic transport necessary for electrolysis, enabling both high productivity and reliability
Solution Approach 2:
The shell layer acts as an intermediary between the core Ni-based particles and the high-temperature steam environment. It mediates the interaction by providing a protective interface that prevents direct contact between steam and core particles, thereby preventing degradation while allowing the electrolysis process to proceed efficiently
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 degradation rate of the electrode is significantly reduced, with rates at 700° C. decreasing to less than 10%/h and further optimization potentially achieving rates of less than 1%/h, maintaining electrode functionality under high-temperature steam exposure.
Implementation Method 1
The electrolytic properties of Ni/YSZ fuel electrodes in SOEC degrade over time due to morphological changes caused by gas-phase diffusion of Ni
Implementation Method 2
a shell composed of a composite oxide containing NiO or Ni
Data Source
AI summary
An electrode includes electrolyte particles and Ni-based particles. The electrolyte particles contain Gd-doped CeO2 (GDC) and/or Gd- and La-doped CeO2 (La-GDC). The Ni-based particles are composed of core-shell particles in which a surface of a core composed of Ni or a Ni-based alloy is partially or fully covered by a shell composed of a composite oxide containing NiO or Ni.