| A fuel cell is a device that can convert chemical energy into electricity directly.The fuel cell is also called a cell because it is composed of electrolyte, anode andcathode, which are the same for a normal cell. The fuel cell generates electricity isthe fourth generation technique after the hydraulic power, thermal power and theatomic energy. Theoretically, As long as continue to supply the fuel, the fuel cell cancontinue to generate electricity then. It generates electricity from fuels such ashydrogen, natural gas and other hydrocarbons. It is Different from traditional cellsthat can only reserve energy;fuel cell can convert energy continuously. Because it isnot limited by the Carnot cycle, fuel cell has advantages of higher energy conversionefficiency and lower polluted gases emission than the traditional generator. With thenatural resource exhaustion and environment deterioration, developing efficient andenvironmental friendly energy techniques is necessary recently. Since fuel cell justmatches such requirements, it attracts the interest all over the world. As the fourth generation fuel cell, SOFC (Solid Oxide Fuel Cell) has manyoutstanding advantages. First, with all solid components, SOFC eliminates problemsliquid electrolyte fuel cell faces, such as corrosion and leakage of liquid electrolytes.Second, operating at high temperatures, its electrode reaction is so fast that it isunnecessary to use noble metals as electrodes. Thus the cost of cells can beminimized. At the same time, the high quality heat it emits can be fully used. Theoverall energy conversion efficiency of the thermal-electric system can be added upto 80%. The most outstanding advantage of SOFC is that it can use a large ofdifferent fuels, from the hydrogen, carbon monoxide to the natural gas, even othercombustive gases. The main difficulty the SOFC faces currently is the problemcaused by high temperature and the ceramic components' match.Today's demonstration SOFCs utilize yttria stabilized zirconia(YSZ) containingtypically 8mol%Y, as the electrolyte;a ceramic-mental composite (cermet)comprised of Ni+YSZ as the anode;and La1-xSrxMnO3-δ,(lanthanum strontiummanganite or LSM)as the cathode,in general, they must operate at high temperaturebecause of the low ionic conductivity of YSZ electrolyte at lower operatingtemperatures, such high operating temperatures cause many serious problems such asphysical and chemical degradation of the SOFCs component materials. Therefore, itis important to reduce the operation temperature of SOFCs, it is desirable to developthe new electrolyte operating at the Intermediate-Temperature (IT) and the electrodematerials that match with it mutually. one path is to make the electrolyte of YSZ intothin film, another is to look for a new electrolyte that work inintermedium-temperature area(600℃-800℃). Because the thin film technique cost ishigh, craft complicacy,So the second path most contain attraction, Recently,intermedium-temperatures (600℃-800℃) SOFC (IT-SOFC) has received muchinterest because a replacement of YSZ by a reduced-temperature oxygen-ionconductor in SOFCs would greatly reduce material and fabrication problems andimproved cell reliability during prolonged operation. So exploring new type ofelectrolyte and electrode andtheir synthesis method is very important for developing IT-SOFC. Now, ceria-basedelectrolytes are noteworthy as candidates for electrolyte materials. because thismaterial contains the electronics conductivity , so make open circuit voltage(OCV)and exportation power of the fuel cell lowered. We can make it into compositematerial that increases the various functions of CeO2.Glycine-nitrate process (GNP) synthesis technique is simple and speedy. Themethod immediately produces high-surface-area compositionally homogeneouspowers. At 1000 K, SDC electrical conductivity is 0.03 s/cm, GDC is 0.28 s/cm.With the traditional solid method, we synthesize the GDC-YSZ compositeelectrolyte. The electrical conductivity of composite electrolyte lower than GDC, butunder the same temperature is equal with YSZ .The function of the battery betterthan the pure electrolyte of GDC below 700℃.Possibly, the machine function of theGDC-YSZ composite electrolyte gets build up.With the solid-liquid method, we synthesize the SDC-NaOH compositeelectrolyte. NiO/SDC as the anode and Sm0.3Sr0.7CoO3 as the cathode, the samplemake into single battery. Within the scope of 600℃～850℃, OCV and powerdensity are all higher than the pure SDC electrolyte. The power density of thecomposite electrolyte is come to 210 mW/cm2 at 750℃. Within the scope of 600℃～800℃,the battery of SDC-NaOH electrolyte's opens circuit voltage higher0.1～0.2V than the battery of SDC electrolyte. The SDC-NaOH electrolyte battery'svoltage can still maintain at 0.958V at 850℃. But above 800℃,the power densitystarts descending, May be the NaOH run off from SDC electrolyte, so the battery'sperformance quickly descend. Therefore, the SDC composite electrolyte, mustfurther improve electrode. Under the fuel cell environment, we computed theelectrical conductivity at 600℃ is 0.024 s/cm, almost 2～3 times than SDC.Improve the electrode and craft, the SDC-NaOH composite electrolyte becomes theideal electrolyte in IT-SOFCs.
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