Page 7 - Read Online

Zhuang et al. Energy Mater. 2025, 5, 500015 https://dx.doi.org/10.20517/energymater.2024.90 Page 3 of 14

-2
[21]
5 mm using the dip-coating method, with a peak power density (PPD) of 810 mW cm at 700 °C .
Although the dip-coating method is simple and inexpensive to prepare anode supports, it is highly
inefficient and unsuitable for large-scale preparation because repeated dip-coating is required to achieve a
certain thickness, similar to the slip-casting . Zou et al. reported a 3D-printed tubular PCFC with an
[22]
efficient area of 12.5 cm and a total power output of 2.45 W at 650 °C . However, the cost of the 3D
[23]
2
printing equipment is excessively high . Compared to the aforementioned methods for tubular PCFCs, the
[24]
extrusion technology is currently one of the most effective methods for preparing tubular cells due to its
economic feasibility, intuitively simple operation, extremely high efficiency, and the ability to prepare
tubular cells of any length and diameter. Nevertheless, the extrusion technology has not been utilized for the
preparation of microtubular PCFCs [25,26] .

The commonly used proton-conducting electrolytes, such as BaZr Ce Y O (BZCY),
0.7 0.2
0.1
3-δ
BaZr Ce Y Yb O (BZCYYb4411), and BaZr Ce Y Yb O (BZCYYb1711), have been extensively
0.1
3-δ
0.4
0.4 0.1
3-δ
0.1
0.7 0.1
0.1
investigated. The commonly used synthesis methods are the sol-gel or the conventional solid-state reaction
(SSR) method [27-29] . The sol-gel method is not suitable for large-scale preparation due to the complexity of
fabrication process and the uncertainty of crystallization water in nitrates. The conventional SSR method,
which uses metal oxides as raw materials, is simple but requires multiple rounds of ball-milling and
calcination. Moreover, the incorporation of trivalent rare-earth metal ions into the crystal lattice is
challenging, leading to the formation of heterogeneous phases. These drawbacks hinder the large-scale
[30]
application of the conventional SSR .
In this work, a novel BaZr Ce Y Gd O (BZCYG4411) electrolyte was synthesized using an extremely
0.4 0.1
0.4
0.1
3-δ
simple and efficient novel one-step SSR method with raw materials including BaCO , Ce Gd O
2-δ
3
0.2
0.8
(GDC20), 8 mol% Y O stabilized ZrO (8YSZ), and Y O . This one-step SSR method requires only a single
2
3
2
3
2
ball-milling and calcination to obtain the pure phase compared to conventional SSR. A microtubular PCFC
(a tube diameter of less than 5 mm) with the configuration of NiO-BZCYG4411 anode support|NiO-
BZCYYb1711 AFL|BZCYYb1711 electrolyte layer|Ba Sc Nb Co Fe O (BSNCF) cathode was
0.1
0.1
2
0.3
1.5
6-δ
successfully prepared using a simple and efficient extrusion technology combined with a dip-coating
method. BSNCF oxide was selected as the cathode due to its low thermal expansion coefficient (TEC),
-2
which has not been applied in tubular PCFCs. The cell achieved high PPDs of 906.86 and 655.56 mW cm
at 700 and 650 °C, respectively. Moreover, the microtubular PCFCs demonstrated favorable stability after
about 103 h durability test at a constant current of 0.5 A cm at 650 °C. This newly developed fabrication
-2
method for BZCYG4411, along with extrusion technology for cell preparation, provides a simple,
economical, and efficient way to fabricate large-scale microtubular PCFCs.
EXPERIMENTAL
Synthesis of electrolyte and cathode powders
The BZCYG4411 oxide was synthesized using a one-step SSR method using two types of raw materials. For
type 1, BaCO (Shanghai Aladdin Biochemical Technology Co., Ltd., 99.95%, China), GDC20 (Ruier Powder
3
Materials Corporation, China), 8YSZ (Sinocera, China), and Y O (Aladdin, 99.99%, China) were weighed
3
2
and mixed according to the stoichiometric ratio, followed by ball-milling in ethanol for 24 h at 300 r/min.
Then the mixture was completely dried at 80 °C in an oven. Subsequently, the dry powder was pressed into
large pellets at 10 MPa with a diameter of 20 mm and then calcined at 1,200 °C for 12 h to obtain pure
BZCYG4411 [Figure 1]. The reaction equation is given in
BaCO + GDC20 + 8YSZ + Y O → BZCYG4411 (1)
3
2
3