Computational engineering of the oxygen electrode-electrolyte interface in solid oxide fuel cells

Kaiming Cheng,Yong Du,Lijun Zhang,Ming Chen,Xitao Wang,Huixia Xu,Jixue Zhou

doi:10.1038/s41524-021-00584-8

Abstract

The Ce0.8Gd0.2O2−δ (CGO) interlayer is commonly applied in solid oxide fuel cells (SOFCs) to prevent chemical reactions between the (La1−xSrx)(Co1−yFey)O3−δ (LSCF) oxygen electrode and the Y2O3-stabilized ZrO2 (YSZ) electrolyte. However, formation of the YSZ–CGO solid solution with low ionic conductivity and the SrZrO3 (SZO) insulating phase still happens during cell production and long-term operation, causing poor performance and degradation. Unlike many experimental investigations exploring these phenomena, consistent and quantitative computational modeling of the microstructure evolution at the oxygen electrode–electrolyte interface is scarce. We combine thermodynamic, 1D kinetic, and 3D phase-field modeling to computationally reproduce the element redistribution, microstructure evolution, and corresponding ohmic loss of this interface. The influences of different ceramic processing techniques for the CGO interlayer, i.e., screen printing and physical laser deposition (PLD), and of different processing and long-term operating parameters are explored, representing a successful case of quantitative computational engineering of the oxygen electrode–electrolyte interface in SOFCs.

Highlights

Owing to the advantages of high-energy efficiency, broad fuel options, low pollutant emissions, and scalable stacks, solid oxide fuel cells (SOFCs) are attracting increasing attention in the clean and efficient generation of electrical power from renewable sources
Within the past two decades, significant progress has been made in the selection of suitable materials of SOFCs to reduce operating temperature from ~1000 to 500–800 °C, of which the latter is known as the intermediate temperature SOFCs (IT-SOFCs)[1,2]
Within the intermediate temperature range, gadolinia-doped ceria (CGO) with high ionic conductivity is regarded as a good electrolyte material for IT-SOFCs, though it may exhibit a minor degree of electronic conductivity at temperatures above 550 °C, reducing the SOFC efficiency[3]

Summary

Introduction

Owing to the advantages of high-energy efficiency, broad fuel options, low pollutant emissions, and scalable stacks, solid oxide fuel cells (SOFCs) are attracting increasing attention in the clean and efficient generation of electrical power from renewable sources. Formation of SZO is the result of Sr diffusion across the CGO barrier layer to the Ce-rich side of IDZ and reaction with ZrO2 dissolved in CeO2, and the process continues during long-term operation at intermediate temperature (Step 3).

Results

Conclusion