Layered Structure And Spinel Structure As Cathode In The Solid Oxide Fuel Cell Performance Study

Solid oxide fuel cells (SOFCs) as new green power generation device directly converting chemical energy to electrical energy have caused broad attentions from researchers of some countries in view of their high-energy conversion efficiency、low environmental impact and good fuel flexibility and other significant advantages, cathode materials as an important part in fuel cell, have important effects on the electrochemical performance of the fuel cell. To date, there has been significant progress by optimizing cathode structures-compositions to decreasing SOFCs operating-temperature, Improve the battery performance and reduce cost in practical application. The spinel-type oxides of Mn1.5Co1.5O4、LiNi0.5Mn1.5O4and layered compounds of LiNi1/3Co1/3Mn1/3O2.(?) prepared via a citrice EDTA acid process were investigated as candidate cathodes of intermediate temperature solid oxide fuel cells (IT-SOFCs). Mn1.5Co1.5O4and LiNi1/3Co1/3Mn1/3O2-δas a new-type of compositecathode materials in the SOFCs’ have high electrical conductivityelectronic conductivity, thermal and structural stability and goodthermal chemical matching with the electrolyte. The latticestructure and phase purity of the as-synthesized powders wereexamined by powder X-ray diffraction (XRD, diffractometer with aCu Ka radiation source, λ=0.15418nm,40kV,40mA) at roomtemperature. the morphologies of the Mn1.5Co1.5O4、LiNi0.5Mn1.5O4and LiNi1/3Co1/3Mn1/3O2-δpowders as well as fuel cell withMn1.5Co1.5O4、LiNi0.5Mn1.5O4and LiNi1/3Co1/3Mn1/3O2-δpowders ascomposite cathode materials on an SDC electrolyte forintermediate temperature of SOFCs, Respectively. Theopen–current voltage characteristics and the correspondingpower densities of a fuel cell with the SDC-Mn1.5Co1.5O4andSDC-LiNi0.5Mn1.5O4composite cathode in a conventional anodesupporting of SDC electrolyte fuel cellNiO-SDC/SDC/SDC-Mn1.5Co1.5O4、 NiO-SDC/SDC/SDC-LiNi0.5Mn1.5O4and SDC-LiNi1/3Co1/3Mn1/3O2-δcomposite cathode in a conventionalanode supporting of SDC electrolyte fuel cellNiO-SDC/SDC/SDC-LiNi1/3Co1/3Mn1/3O2-δwere then investigatedwith humidified hydrogen (3vol%H2O) as fuel and air as oxidant.The diffraction peaks results show structures of LiNi1/3Co1/3Mn1/3O2-δspecimen material is a well-defined layerstructure, characteristic peak sharp show of high degree ofcrystallinity and complete crystal shape. A single layered rocksalt structure form in calcination at850℃. The diffraction peak ofMn1.5Co1.5O4spinel showed no other impurity peak is a dual phasematerial, containing both the MnCo2O4cubic spinel structure andMn2CoO4tetragonal spinel structure. electrochemical test at500℃、550℃、600℃、650℃of the SDC-Mn1.5Co1.5O4compositecathode in a conventional anode supporting SDC electrolyte fuelcell NiO-SDC/SDC/SDC-Mn1.5Co1.5O4, The open circuit voltage is0.722V、0.71V、0.6961V、0.6937V and maximum power density is258mW cm-2、530mW cm-2、774mW cm-2、1101mW cm-2,respectively. LiNi0.5Mn1.5O4is cubic spinel structure,electrochemical test at600℃、700℃of the SDC-LiNi0.5Mn1.5O4composite cathode in a conventional anode supporting SDCelectrolyte fuel cell NiO-SDC/SDC/SDC-LiNi0.5Mn1.5O4, The opencircuit voltage is0.6701V、0.6424V and maximum power densityis64mWcm-2、519mWcm-2, The SDC-LiNi1/3Co1/3Mn1/3O2-δcomposite cathode in a conventional anode supporting SDCelectrolyte fuel cell NiO-SDC/SDC/SDC-LiNi1/3Co1/3Mn1/3O2-δelectrochemical test results show that the open circuit voltage is0.819V、0.796V、0.765V、0.723V and maximum power density is 427mW cm-2、730mW cm-2、1099mW cm-2、1191mW cm-2,respectively. The electrochemical experiments on theperformances show that the activity of (Mn, Co)3O4spinel oxidesand layered compounds of LiNi1/3Co1/3Mn1/3O2-δare good. All theresults show that spinel-type oxides and Layered structureoxides are potential cathodes materials for IT-SOFCs.