Nb掺杂对Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)Nb_xO_3(0≤x≤0.15)阴极材料电化学性能影响的研究

Study on the influence of electrochemical performance of Nb-doped Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x)Nb_xO_3(0≤x≤0.15) cathode material

为了研究Nb掺杂对于Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_3阴极材料的电化学性能的影响,采用燃烧法合成了Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x) Nb_xO_3(BSCFN_x,x=0、0.05、0.1、0.15),并将其作为固体氧化物燃料电池(solid oxide fuel cell,SOFC)阴极材料进行性能测试。XRD结果显示,所有Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x)Nb_xO_3样品均为立方型钙钛矿相,没有杂质出现。电导率测试结果显示,随着Nb含量的增加,BSCFN_x的电导率和电化学输出性能均随之先上升、后下降,Nb的最佳掺杂比例为Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.1)Nb_(0.1)O_3(BSCFN0.1)。在800℃下,BSCFN0.1的电导率高达36.3S/m。在700℃下,以BSCFN0.1为阴极的氧化钆掺杂的氧化铈(Ce_(0.9)Gd_(0.1)O_2GDC)为电解质支撑单电池的最大功率密度可以达到194 mW/cm^2,比其他Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x)Nb_xO_3(x=0、0.05、0.15)阴极基GDC电解质支撑的单电池最大功率密度明显增大。功率密度测试结果与电导率测试结果相一致,说明Nb的掺杂对于提高BSCF的电导率以及氧化还原反应(oxygen reduction reaction,ORR)催化性能具有显著效果,且当x=0.01时为最佳。

To investigate the influence of Nb doping on the electrochemical properties of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x)Nb_xO_3 cathode materials,Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x)Nb_xO_3oxides(BSCFN_x,x =0,0.05,0.1,0.15)have been synthesized by the conventional Glycinenitrate process and they were investigated as a cathode for intermediate temperature solid fuel cells(IT-SOFCs).XRD patterns show that the all of the samples are pure cubic perovskites without any impurity phase.Electrical conductivity behaviors of the BSCFN_xsamples demonstrate that with the increase of Nb content,the electrical conductivity and electrochemical output of BSCFN_xboth rise first and then decrease,and the optimum doping ratio of Nb is Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.1)Nb_(0.1)O_3(BSCFN0.1).BSCFN0.1 has the highest electronic conductivity withσ=36.3S/m at 800℃.The maximum power density of a single-cell with BSCFN0.1 cathode reaches to 194 mW/cm^2 at 700 ℃,which is significantly larger than those of other Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x) Nb_xO_3(x=0,0.05,0.15)cathode based GDC electrolyte.Single-cell performance testing results are consistent with the electrical conductivity testing results,indicating that the doping of Nb has remarkable effect on improving the conductivity of BSCF and the catalytic performance of ORR(oxygen reduction reaction),and when x = 0.01 is the best.