Improving the electrochemical energy conversion of solid oxide fuel cells through the interface effect in La0.6Sr0.4Co0.2Fe0.8O3-δ-BaTiO3-δ electrolyte

Hongdong Cai; Dan Zheng; Chen Xia; LeiLei Zhang; Xunying Wang; Wenjing Dong; Xu Chen; Hao Wang; Baoyuan Wang

doi:10.1016/j.jcis.2023.03.054

Improving the electrochemical energy conversion of solid oxide fuel cells through the interface effect in La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ-BaTiO_3-δ electrolyte

J Colloid Interface Sci. 2023 Jul:641:70-81. doi: 10.1016/j.jcis.2023.03.054. Epub 2023 Mar 11.

Authors

Hongdong Cai¹, Dan Zheng¹, Chen Xia¹, LeiLei Zhang², Xunying Wang¹, Wenjing Dong¹, Xu Chen³, Hao Wang⁴, Baoyuan Wang⁵

Affiliations

¹ School of Microelectronics, Hubei University, Wuhan, Hubei 430062, China.
² College of Sciences, Liaoning Petrochemical University, Fushun 113001, China.
³ Hubei Jiufengshan Laboratory, Future Science and Technology City, Wuhan 420000, China. Electronic address: chenxu@jfslab.com.cn.
⁴ School of Microelectronics, Hubei University, Wuhan, Hubei 430062, China. Electronic address: nanoguy@126.com.
⁵ School of Microelectronics, Hubei University, Wuhan, Hubei 430062, China. Electronic address: baoyuanw@163.com.

PMID: 36924547
DOI: 10.1016/j.jcis.2023.03.054

Abstract

Herein, we present a heterostructure electrolyte with considerable potential for application in low-temperature solid oxide fuel cells (LT-SOFCs). Heterostructure electrolytes are advantageous because the multiphase interfaces in their heterostructures are superior for ion conduction than for bulk conduction. Most previous studies on heterostructure electrolytes explained the influence of interfacial parameters on ion conduction in terms of the space charge zones and lattice mismatch, neglecting the characterization of the interface. In this study, a series of heterostructure electrolytes comprising La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) and BaTiO_3-δ (BTO) with different composition ratios was developed. Further, the lattice mismatch due to thermal stress in this system was evaluated by thermal expansion and electron energy loss spectroscopy (EELS) analyses. Results indicated that 7LSCF-3BTO produced the narrowest interface and the most surface oxygen vacancies, suggesting that the stress generated by thermal expansion increased the density of the interface. The cell with the optimal 7LSCF-3BTO composition delivered a peak power density of 910mW cm^-2 and an open circuit voltage of 1.07 V at 550 °C. The heterojunction effect was studied to elucidate the prevention of short circuiting in the LSCF-BTO cell, considering the Femi level and barrier energy height. This study provides novel ideas for the design of electrolytes for LT-SOFCs from the interface perspective.

Keywords: Built-in electric field; Ionic conductivity; Lattice mismatch; Thermal expansion stress.