Preparation And Properties Of BaZr_0.63 Ce_0.27 Y_0.1-x Yb_x O_2.95/ Salt Composite Proton Conductors

BaZr_0.63Ce_0.27Y_0.1-xYb_xO_2.95 （x=0, 0.05 and 0.1） based composite electrolyte materials were synthesized via solid-state reaction process. After sintering at at 1600℃for 4 h, BZCY, BZCYYb and BZCYb samples were obtained. The linear shrinkages and relative densities decrease with increasing Yb content. A maximum linear shrinkage of 14.8% and relative density of 87.8 % were achieved for BZCY after sintered at 1600℃for 4 h; meanwhile,the conductivity of the sample BZCY was 2.14×10-3 Scm-1 at 800℃in wet hydrogen.The influences of ZnO additive on sintering and electrical behavior were systemic investigated. After sintering at 1450 ?C for 6 h, the relative densities of BZCY-Z2 series samples were all above 93%, higher than that without ZnO addition. XRD patterns showed a single perovskite structure of BZCY-Z2 after sintering at 1450℃for 6 h. A conductivity of 7.64×10-3 Scm-1 for BZCY-Z2 was obtained at 800℃, while a minimum activation energy of 0.49 eV was obtained for BZCYYb-Z2 sample. An anode-supported cell based on BZCY-Z2 delivered a peak power density of 56 mWcm-2 at 700℃.After sintering at 1370℃for 2 h, the relative densities of Na₂SO₄-modified BZCY-Z2 samples were above 92% and the linear shrinkages were above 17%, which suggested that Na₂SO₄ was an effective liquid phase sintering additive. A superprotonic phase transition was found in Na₂SO₄-modified BZCY-Z2 samples and a conductivity of 8.05×10-3 Scm-1 was obtained for BZCY-Z2-S10 sintered at 1370℃for 2 h at 700℃in 3% wet hydrogen atmosphere. An electrolyte-supported cell based on BZCY-Z2-S10 delivered a peak power density of 23 mWcm-2 at 700 ?C.NaCl was added as the second phase to prepare BZCY-Z2-Cl proton conductor. After sintering at 1400℃for 4 h, the conductivity of BZCY-Z2-Cl10 reached 7.48×10-3 Scm-1, higher than that of BZCY-Z2. An electrolyte-supported cell based on BZCY-Z2-S10 delivered a peak power density of 16 mWcm-2 at 700℃. Ionic transport number of fuel cell based on BZCY-Z2-Cl10 electrolyte was 0.97, 0.97, 0.95and 0.93 at 550, 600, 650 and 700 ?C, respectively, which suggested that BZCY-Z2-S10 was a good proton conductor material.