High performance Mn1.3Co1.3Cu0.4O4 spinel based composite cathodes for intermediate temperature solid oxide fuel cells

Self Cite

Solid oxide cells (SOCs) are mutually convertible energy devices capable of generating electricity from chemical fuels including hydrogen in the fuel cell mode and producing green hydrogen using electricity from renewable but intermittent solar and wind resources in the electrolysis cell mode. An effective approach to enhance the performance of SOCs at reduced temperatures is by developing highly active oxygen electrodes for both oxygen reduction and oxygen evolution reactions. Herein, highly conductive Sm3+ and Nd3+ double-doped ceria (Sm0.075Nd0.075Ce0.85O2−δ, SNDC) is utilized as an active component for reversible SOC applications. We develop a novel La0.6Sr0.4Co0.2Fe0.8O3 −δ (LSCF)–SNDC composite oxygen electrode. Compared with the conventional LSCF–Gd-doped ceria oxygen electrode, the LSCF–SNDC exhibits ∼35% lower cathode polarization resistance (0.042 Ω cm2 at 750 °C) owing to rapid oxygen incorporation and surface diffusion kinetics. Furthermore, the SOC with the LSCF–SNDC oxygen electrode and the SNDC buffer layer yields a remarkable performance in both the fuel cell (1.54 W cm–2 at 750 °C) and electrolysis cell (1.37 A cm–2 at 750 °C) modes because the incorporation of SNDC promotes the surface diffusion kinetics at the oxygen electrode bulk and the activity of the triple phase boundary at the interface. These findings suggest that the highly conductive SNDC material effectively enhances both oxygen reduction and oxygen evolution reactions, thus serving as a promising material in reversible SOC applications at reduced temperatures.

Section: Resultsmentioning

confidence: 99%

Enhancing Bifunctional Electrocatalytic Activities of Oxygen Electrodes via Incorporating Highly Conductive Sm³⁺ and Nd³⁺ Double-Doped Ceria for Reversible Solid Oxide Cells

Park

Jung

Kim

et al. 2021

Self Cite

“…Solid oxide fuel cells (SOFCs) have garnered widespread academic and industrial attention due to their high energy conversion efficiencythe overall system efficiency reaches up to 85%outstanding fuel adaptability, and environment-friendly operation. − Unfortunately, the successful realization of SOFCs is challenged by high operating temperatures (up to 1000 °C), resulting in interfacial reactions between different components and limiting the choice of interconnects and sealing materials. Consequently, several research groups aimed to reduce the operating temperature and develop intermediate-temperature SOFCs, operating in the temperature range of 600–800 °C. − …”

Section: Introductionmentioning

confidence: 99%

Boosting the Electrochemical Performance of Fe-Based Layered Double Perovskite Cathodes by Zn²⁺ Doping for Solid Oxide Fuel Cells

Ren

Wang

Meng

et al. 2020

117

Mixed oxygen ionic and electronic conduction is a vital function for cathode materials of solid oxide fuel cells (SOFCs), ensuring high efficiency and low-temperature operation. However, Fe-based layered double perovskites, as a classical family of mixed oxygen ionic and electronic conducting (MIEC) oxides, are generally inactive toward the oxygen reduction reaction due to their intrinsic low electronic and oxygen-ion conductivity. Herein, Zn doping is presented as a novel pathway to improve the electrochemical performance of Fe-based layered double perovskite oxides in SOFC applications. The results demonstrate that the incorporation of Zn ions at Fe sites of the PrBaFe2O5+δ (PBF) lattice simultaneously regulates the concentration of holes and oxygen vacancies. Consequently, the oxygen surface exchange coefficient and oxygen-ion bulk diffusion coefficient of Zn-doped PBF are significantly tuned. The enhanced mixed oxygen ionic and electronic conduction is further confirmed by a lower polarization resistance of 0.0615 and 0.231 Ω·cm2 for PrBaFe1.9Zn0.1O5+δ (PBFZ0.1) and PBF, respectively, which is measured using symmetric cells at 750 °C. Moreover, the PBFZ0.1-based single cell demonstrates the highest output performance among the reported Fe-based layered double perovskite cathodes, rendering a peak power density of 1.06 W·cm–2 at 750 °C and outstanding stability over 240 h at 700 °C. The current work provides a highly effective strategy for designing cathode materials for next-generation SOFCs.

“…The peaks located at 641.1 and 642.3 eV are attributed to Mn 2+ in the tetrahedral site. The other peaks are attributed to Mn 3+ (640.1 and 653.2 eV) and Mn 4+ (643.7 and 655.6 eV), which occupy the octahedral site. ,, The percentages of Mn ions of the samples are displayed in Figure b. For MnCo 2 O 4 , there are 43.3% Mn 2+ in the tetrahedral site and 38.3% Mn 3+ and 18.4% Mn 4+ in the octahedral site.…”

Section: Resultsmentioning

confidence: 98%

“…, SrFeO 3 , LaCuO 3 , and La 2 NiO 4+δ ) are developed as cathode materials for IT-SOFC. − Nevertheless, the possibility of practical application is reduced by their low ORR catalytic activity. Recently, spinel-type oxides, such as MnCo 2 O 4 , CuCo 2 O 4 , and CuFe 2 O 4 , have gradually attracted attention due to their high electronic conductivity. − However, it is almost impossible to achieve sufficient ORR kinetics in the intermediate temperature range because of their low ionic conductivity. Thus, it is difficult for a single-phase material to meet the requirements of an excellent cathode, including high catalytic activity, good thermal stability, high conductivity, excellent mechanical compatibility, and remarkable chemical stability. ,,, …”

Section: Introductionmentioning

confidence: 99%

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

Wang

Zhang

Meng

et al. 2021

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 (Mn0.6Mg0.4)0.8Sc0.2Co2O4 (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 (Mn0.6Mg0.4)0.8Sc0.2Co2O4 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.