固態燃料電池LSGM-SDC複合電解質微結構及電性之探討

Microstructural and Electrical Properties Analysis of LSGM-SDC Composite Electrolytes Used in the Solid Oxide Fuel Cell

李明晉(Ming-Jin Lee) ； 黃洧瀚(Wei-Han Huang) ； 吳玉娟(Yu-Chuan Wu)

《臺灣鑛業》 67卷4期 (2015/12) Pp. 46-62

摘要

中溫型固態氧化物燃料電池以固態合成反應法製備成複合電解質試片(100-xwt%)La_(0.85)Sr_(0.15)Ga_(0.8)Mg_(0.2)O_(2.825)（LSGM1520）+（xwt%）Ce_(0.85)Sm_(0.15)O_(1.925)（SDC15）（x=0、2、5、7、10、100）。複合電解質的顯微結構與電性能藉由X光繞射儀、拉曼光譜儀、掃描式電子顯微鏡（SEM）、熱機械分析儀（TMA）和交流阻抗頻譜儀來分析。兩種電解質LSGM1520和95wt%LSGM1520-5wt%SDC15製作為電池，其兩側分別為La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ）（LSCF6428）陰極和Ce_(0.8)Sm_(0.2)O_(1.9)-Ni（SDC20Ni）陽極，並且使用電化學儀器量測其功率密度。結果顯示，複合電解質包含擬立方鈣鈦礦結構與立方螢石結構相。當SDC15含量大於5wt%，SrLaGa3O7相更容易生成在複合電解質中，並且可發現LSGM1520中的La^(3+)離子擴散至SDC15。複合試片的最大緻密化應變率（□）主要發生在1,300~1,400℃之間。LSGM1520與LSGM2015-SDC15複合試片的熱膨脹係數在200~600℃時為10.5×10^(-6)/℃至12×10^(-6)/℃，在600~800℃時為12×10^(-6)/℃至15×10^(-6)/℃。在650~700℃時95L05S電解質比起LSGM1520而言，95L05S可以明顯的增加全電池性能，但它的性能在高於750℃時則衰減。對於性能與電流密度的分析，LSCF6428/LSGM1520/SDC20-Ni（電池A）在774℃時可達264mW/cm^2與1.00A/cm^2，LSCF6428/95L05S/SDC20-Ni（電池B）在789℃可達182mW/cm^2與0.97A/cm^2。兩者的開路電壓（OCV）是約1.0~1.1V。

關鍵字

態燃料電池 ； 導電機制 ； 複合電解質 ； 顯微結構 ； 燒結

並列摘要

(100-x wt%) La_(0.85)Sr_(0.15)Ga_(0.8)Mg_(0.2)O_(2.825) (LSGM1520)+(x wt%) Ce_(0.85)Sm_(0.15)O_(1.925) (SDC15) (x=0, 2, 5, 7, 10, and 100) samples were synthesized by a solid-state reaction for use as a composite electrolyte in an intermediate-temperature solid oxide fuel cell (SOFC). The microstructures and electrical properties of the composite electrolytes were analyzed by X-ray diffractometry, Raman spectroscopy, scanning electron microscopy, thermomechanical analysis, and AC impedance spectroscopy. Two kinds of electrolytes, LSGM1520 and 95 wt% LSGM15205 wt% SDC15, based on a La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) (LSCF6428) cathode and Ce_(0.8)Sm_(0.2)O_(1.9)Ni (SDC20Ni) anode were used to form two SOFCs, and their power densities were measured using an electrochemical instrument. The results show that the composites contain pseudo-cubic perovskite and cubic fluorite phases. For a SDC15 content greater than 5 wt%, SrLaGa_3O_7 was obtained in the composite, and diffusion of La^(3+) from LSGM1520 to SDC15 was observed. The maximum densification strain rates (□) of the composites mainly occurred between 1,300 and 1,400℃. The thermal expansion coefficients (TECs) of the LSGM1520 and LSGM2015-SDC15 composites ranged from 10.5×10^(-6)/℃ to 12×10^(-6)/℃ at 200~600℃ and from 12×10^(-6)/℃ to 15×10^(-6)/℃ at 600-800℃, respectively. The 95L05S electrolyte significantly enhanced the fuel cell performance compared to LSGM1520 at 650-700℃, but the performance deteriorated above 750℃. The performances and current density of LSCF6428/ LSGM1520/SDC20-Ni (Cell A) and LSCF6428/95L05S/SDC20-Ni (Cell B) were 264 mW/cm2 and 1.00 A/cm2 at 774℃, and 182 mW/cm2 and 0.97 A/cm2 at 789℃, respectively, and their open circuit voltages (OCV) were 1.0~1.1 V.

並列關鍵字

solid oxide fuel cell ； conductivity mechanism ； composite electrolyte ； microstructure ； sintering