Cui Qiao,Jie Yu,Guoqiang Lv,Shaoyuan Li,Jijun Lu,Fengshuo Xi,Zhongqiu Tong,Wenhui Ma
Y 0.15 Zr 0.85 O 1.93 (YSZ) has emerged as a crucial solid electrolyte material for modern solid oxide fuel cells (SOFCs) and oxygen sensors, prized for its exceptionally high oxygen ionic conductivity. However, further enhancement of its oxygen ionic conductivity is essential to optimize SOFCs energy efficiency and mitigate high-temperature electrode degradation. Despite extensive efforts involving various doping strategies, this critical challenge remains unsolved. To address this issue, a novel YSZ-LSGM heterostructure composite electrolyte was developed by adding a minor La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 (LSGM) phase into the YSZ phase, and its performance as an electrolyte was systematically evaluated. LSGM’s high ionic conductivity promotes rapid oxygen ion transport across grain boundaries. The heterogeneous interface between YSZ and LSGM also favors oxygen ion transport, significantly enhancing both the grain boundary conductivity and the total ionic conductivity of the heterostructure composite. Remarkably, the YSZ-30 wt% LSGM composite demonstrates approximately 8 times in total conductivity (0.0008 S/cm at 750 °C) compared to pure YSZ (0.0001 S/cm at 750 °C). Most strikingly, the YSZ-30 wt% LSGM’s grain boundary conductivity is around 24 times higher than the YSZ electrolyte’s. These findings highlight the synergistic advantages of the heterostructure composite electrolyte, which combines the excellent compatibility of YSZ with the superior ionic conductivity of LSGM. This study not only provides a promising strategy for developing advanced composite electrolyte materials but also opens a new avenue for further research in high-performance SOFC technologies.
Jing-Hui Zhang,Dong-Chu Lu,Hai-Yan Mao,Shan-Lin Zhang,Cheng-Xin Li
One significant challenge of using Sr and Mg doped LaGaO 3 (LSGM) as an electrolyte for solid oxide electrochemical cells lies in attaining a high-purity phase and exceptional ionic conductivity through a straightforward and cost-effective fabrication process. This study introduces an innovative approach to synthesizing high-purity phase LSGM electrolytes by incorporating Li oxides as a phase formation additive within the conventional solid-state reaction method. The impact of Li oxides addition on the phase structure, sintering characteristics, and conductivity of LSGM electrolytes is thoroughly characterized. Results indicate that addition of 1 mol% Li completely eliminates La 2 O 3 impurities, yielding an LSGM electrolyte with a high-purity phase structure. However, increasing Li to 1.5 and 2 mol% introduces common impurities such as LaSrGa 3 O 7 and LaSrGaO 4 . Notably, the high-purity phase LSGM with 1% Li demonstrates impressive oxygen ionic conductivity. At 800 °C, the conductivity reaches 0.195 S cm −1 and shows remarkable stability across a wide range of oxygen partial pressures. Furthermore, a full cell employing a ∼200 μm high-purity phase LSGM electrolyte achieves an output power density of 1.5 W cm −2 in solid oxide fuel cell mode and a current density of 3.02 A cm −2 at 1.5 V in steam electrolysis mode at 800 °C.
Ca 3 Co 4 O 9+δ (CCO) cathode has been extensively studied for its excellent thermal expansion matching with commonly used electrolytes. CCO composite cathode with different concentrations of La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3 (LSGM) was prepared to evaluate its performance on LSGM electrolyte in this work. The appropriate amount of LaCoO 3 generated by the in-situ reaction of CCO and LSGM under operating conditions significantly enhances the oxygen exchange ability of CCO cathodes. The composite cathode containing 60 wt. % CCO and 40 wt. % LSGM (C-LGM60) exhibits the best electrochemical performance and the lowest polarization impedance among the C-LGM series cathodes. The area-specific resistance (ASR) of C-LGM60 is 0.06 Ωcm 2 at 750 °C. The maximal power density of the electrolyte-supported cell with C-LGM60 cathode reaches 489 mWcm -2 at 800 °C. After a 10 h stabilizing, there is no observable decline of the cell during the next 40 h of discharge. These results encourage the research of using CCO cathode on LSGM electrolytes and make valuable improvements on the development of SOFC cathode.
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