Effectively Promoting Activity and Stability of a MnCo2O4-Based Cathode by In Situ Constructed Heterointerfaces for Solid Oxide Fuel Cells

Haocong Wang; Wenwen Zhang; Junling Meng; Yongli Pei; Xin Qiu; Fanzhi Meng; Xiaojuan Liu

doi:10.1021/acsami.1c06757

Effectively Promoting Activity and Stability of a MnCo₂O₄-Based Cathode by In Situ Constructed Heterointerfaces for Solid Oxide Fuel Cells

ACS Appl Mater Interfaces. 2021 May 26;13(20):24329-24340. doi: 10.1021/acsami.1c06757. Epub 2021 May 12.

Authors

Haocong Wang^{1

2}, Wenwen Zhang^{1

3}, Junling Meng¹, Yongli Pei⁴, Xin Qiu¹, Fanzhi Meng⁴, Xiaojuan Liu^{1

2}

Affiliations

¹ State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
² University of Science and Technology of China, Hefei 230026, Anhui, China.
³ Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
⁴ School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China.

PMID: 33978394
DOI: 10.1021/acsami.1c06757

Abstract

The development of multiphase composite electrocatalysts plays a key role in achieving the efficient and durable operation of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a self-assembled nanocomposite is developed as the oxygen reduction reaction (ORR) catalyst for IT-SOFCs through a coprecipitation method. The nanocomposite is composed of a doped (Mn_0.6Mg_0.4)_0.8Sc_0.2Co₂O₄ (MMSCO) spinel oxide (84 wt %), an orthorhombic perovskite phase (11.3 wt %, the spontaneous combination of PrO₂ additives and spinel), and a minor Sc₂O₃ phase (4.7 wt %). The surface of the (Mn_0.6Mg_0.4)_0.8Sc_0.2Co₂O₄ phase is activated by the self-assembled nanocoating with many heterogeneous interfaces. Thence, the ORR kinetics is obviously accelerated and an area-specific resistance (ASR) of ∼0.11 Ω cm² is obtained at 750 °C. Moreover, a single cell with the cathode shows a peak power density (PPD) of 1144.1 mW cm^-2 at 750 °C, much higher than that of the cell with the MnCo₂O₄ cathode (456.2 mW cm^-2). An enhanced stability of ∼120 h (0.8 A cm^-2, 750 °C) is also achieved, related to the reduced thermal expansion coefficient (13.9 × 10^-6 K^-1). The improvement in ORR kinetics and stability can be attributed to the refinement of grains, the formation of heterointerfaces, and the enhancement of mechanical compatibility.

Keywords: co-precipitation; heterogeneous interfaces; oxygen reduction reaction; solid oxide fuel cell; spinel.