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Page 6 of 14 Zhuang et al. Energy Mater. 2025, 5, 500015 https://dx.doi.org/10.20517/energymater.2024.90

Characterization
The phase structure of the electrolyte and cathode powders was characterized by X-ray diffraction (XRD,
Bruker D8 Advance, Germany). The high-resolution image, diffraction pattern, and element distribution of
BZCYG4411 powder was characterized using high-resolution transmission electron microscopy (HR-TEM,
FEI talos F200x G2, USA) equipped with energy-dispersive X-ray (EDX) mapping. The powder of
BZCYG4411 and the surface and cross-sectional microstructure of microtubular PCFCs were observed
using field scanning electron microscopy (FSEM, TESCAN MAIA3 LMH, Czech). The electrical
conductivity of BZCYG4411 was measured by four-probe direct current (DC) method from 500 to 700 °C
using the electrochemical workstation. The TEC and linear shrinkage of samples were evaluated in ambient
air using the dilatometer (DIL 402 C, NETZSCH).

RESULTS AND DISCUSSION
Characterization of electrolytes and cathode
Figure 3A presents the XRD patterns of BZCYG4411 oxide (type 1) prepared by the one-step SSR method
and commercial BZCYYb4411 oxide. The BZCYYG4411 exhibits eight broad peaks at 29.25°, 36.00°, 41.85°,
51.89°, 60.71°, 68.86°, 76.49°, and 83.96°, corresponding to the (110), (111), (200), (211), (220), (310), (222),
and (321) crystal planes, respectively. These peaks matched well with the BZCYY4411 oxide and
BaZr Ce Y O (PDF#01-090-2002) oxide. No impurity phases were observed. In contrast, the
2.89
0.4 0.2
0.4
BZCYG4411 synthesized using metal oxide as raw materials (type 2) shows several additional oxide peaks,
as shown in Supplementary Figure 1. Therefore, the type 1 of BZCYG4411 was used for further
investigation. Figure 3B illustrates the XRD refinement of BZCYG4411 (type 1) with lattice parameters of
a = 6.08 Å, b = 8.61 Å, c = 6.11 Å (Space group: Imma, R = 7.92%, R = 10.57%, GOF = 1.28,
wp
p
Supplementary Table 1). Supplementary Figure 2 shows the scanning electron microscopy (SEM) image of
the BZCYG4411 powder and EDX mapping results, indicating that the synthesized powder elements are
extremely homogeneous. The high resolution-transmission electron microscopy (HR-TEM) image is shown
in Figure 3C, revealing a lattice spacing of 0.150 nm, corresponding to the (220) crystal plane. The elemental
distribution of BZCYG4411 was further investigated using high-angle annular dark field scanning
transmission electron microscopy (HAADF-STEM) coupled with EDX mapping results. The Ba, Zr, Ce, Y,
Gd, and O elements were uniformly distributed, with the atomic ratios closely matching the theoretical
stoichiometric values, as shown in Figure 3D. These results demonstrate an effective and cost-efficient
method for synthesizing BZCYG4411 using a simple one-step SSR method, with BaCO , GDC20, 8YSZ, and
3
Y O as raw materials. In order to further confirm the chemical and structure stability of BZCYG4411
2
3
electrolyte, the BZCYG4411 pellet was heat treated in 10% H O-90% N and 3% CO -97% N at 650 °C for
2
2
2
2
50 h, respectively. Supplementary Figure 3 displays the XRD patterns of BZCYG4411 after the treatment,
showing that no impurity peak was generated. These results indicate that BZCYG4411 can maintain good
chemical and structure stability in both H O and CO atmospheres.
2
2
Figure 4A shows the electrical conductivity of BZCYG4411 measured by four-probe DC method at
500-700 °C in both dry and wet air (3 vol% H O). The electrical conductivity increases gradually with
2
temperature from 500 to 700 °C, exhibiting p-type semi-conducting behavior . The BZCYG4411 oxide
[36]
exhibited higher conductivity in wet air compared to dry air, which is attributed to the increased proton
concentration resulting from the hydration reaction. Meanwhile, it can be seen that the BZCYG4411 shows
comparable conductivity in both wet and dry air conditions to that of commonly used proton-conducting
electrolytes, such as BZCYYb4411, BaZr Ce Y Yb O (BZCYYb3511), and BZCYYb1711 [28,36,37] , making
3-δ
0.3
0.5 0.1
0.1
it a viable candidate for application in PCFCs. The E of an electrolyte can be defined as the energy barrier
a
that internal carriers must overcome to facilitate their movement and conduction within the electrolyte,
thereby enabling the electrochemical reaction to occur . Figure 4B shows the Arrhenius plots of
[38]
conductivity of BZCYG4411 oxide. The E of 0.43 eV in wet air is lower than 0.48 eV in dry air, further
a