| A fuel cell is a electrochemical device that can convert chemical energy into electricity directly.It consists of anode,cathode and electrolyte.When fuel in the anode is oxidized and the oxidant is reduced at the cathode,the electrochemical reaction is completed. Fuel cell has the advantages:Energy conversion efficiency,low-pollution.Under the pressure of the rapid growth of demand for electricity, fuel cells are widespread concerned.As the fourth generation of fuel cell, Solid oxide fuel cells (referred to as SOFC) have advantages of Energy conversion efficiency and low-pollution.Application of solid oxide fuel cells has become the current hot research. As the traditional SOFC needs to work in the high temperature(about 1000oC),it brings many problems of materials and production for the fuel cell.Researchers are increasingly aware of the importance of reducing operating temperature.The electrolyte of SOFC as the core component is directly related to the performance of the fuel cell. High-performance electrolyte materials should have sufficiently high ionic conductivity, sufficiently high strength and toughness, low cost and the stability in the atmosphere of the oxidation and reduction. The electrolyte of traditional SOFC is usually 8% mol of yttria stabilized zirconia (YSZ).But it can only have a sufficiently high ionic conductivity in the high temperature.It increases the difficulties of the material selection and preparation.So reducing the temperature is the primary problem. At this stage,there is two ways to solve this problem: First, thin films of YSZ electrolyte; Second,exploring of the new low-temperature electrolyte.Because of the high cost of thin film technology and the complexity of process, the second approach is more feasible.Due to the low operating temperature,it expand the choice of fuel cell materials, reduce the difficulty of making components and extend the life of the fuel cell.So IT-SOFC is of great significance.At this stage,CeO2-based electrolyte is the most promising electrolyte materials in the low-temperature solid oxide fuel cell. However, due to the low mechanical strength of the material and electronic conductivity,it seriously affect the output performance of fuel cells.This paper has prepared a new hybrid solid electrolyte which has the oxygen ion/proton conductivity. Ce0.85Sm0.15O1.925(SDC)which is the oxygen ion electrolyte material is the matrix of the composite electrolyte. BaCe0.8Y0.2O3-δwhich is the proton electrolyte is the dispersed phase of the composite electrolyte. And this thesis has studied the microstructure and electrical properties of this new type of composite electrolyte.We select Sm doped CeO2 as the matrix and mix with the second phase BCY20.Composite material SDC-BCY20 can make full advantage of the two compositions of electrolyte materials. Experimental results show that the conductivity of the composite electrolyte materials SB95 and SB85 are both higher than SDC from 300oC to 800oC.And the performance of fuel cells of SB95 and SB85 are better than SDC and BCY20.The open circuit voltages of composite materials are higher than SDC.The performance of composite electrolyte SB95 is the best.Its power denstity is 0.526W/cm2 in the temperature of 750 oC.Selecting the SDC (85wt.%)-BCY20 (15wt.%) component of the sample in the previous chapter,we analyze the performance characteristics of the samples at different sintering temperature(1250 oC,1350 oC,1400 oC and 1450 oC). The results show that the conductivity of SB85 sintered in 1400 oC is 0.04642 S·cm-1 and the power density of SB85 sintered in 1400 oC is 0.478 W/cm2. However,the electrolyte of SB85 which is sintered in the 1250 oC is not dense. Its conductivity, single-cell output performance and open circuit voltage are the lowest.In summary,the novel composite electrolyte SDC-BCY20 ultimately improve the performance of low temperature electrolyte.
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