| Fuel cell is a highly efficient device that directly converts chemical energy into elect-rical energy.Sealing materials are the key to limiting the development of Solid Oxide Fuel Cell?SOFC?.SOFC requires sealing materials to isolate fuel gas and air?adjacent compo-nent thermal expansion coefficient matching?chemical stability at high temperatures and so on.In order to solve these problems,the medium temperature SOFC of Ce0.8Gd0.2.2 O1.9?GDC?electrolyte is used as the technical background.Research and development of seali-ng materials that can satisfy GDC electrolyte SOFC.This experiment is based on the Al2O3-SiO2-B2O3-CeO2 system.Using CaO,BaO and Na2O as additives?15%?to select.Test its thermal expansion coefficient and hemisphere temperature.The thermal expansion coefficients are 8.773×10-6K-1,8.017×10-6K-11 and10.395×10-6K-1,respectively.The hemisphere temperatures are 700?,750?and 750?,respectively.Adding Na2O has the largest thermal expansion coefficient,so choose Na2O as an additive.Based on Al2O3-Na2O-SiO2-B2O3,calculate the phase diagram of Al2O3 at10%,20%and 30%in the system at 550800?.Select 28%,37%,47%,53%,and 89%of the liquid phase to test Single cell sealing performance.When liquid phase in the 28%,its cannot connect the battery components.It is too much fluidity when liquid phase in the89%.They can achieve good sealing when the liquid phase accounted for 37%,47%and53%.The open circuit voltage of single cells can reach 0.92V,0.93V and 0.96V respectiv-ely.In order to improve the thermal expansion coefficient of Al2O3-SiO2-B2O3-Na2O-Ce O2 system.Continue to increase the amount of Na2O in the sealing material.Preparation of sealing materials with Al2O3 ratio of 10%,20%and 30%respectively.Because of the incr-ease of Na2O,the thermal expansion coefficient of the sealing material increases to 11.25×10-6K-1.As the content of Al2O3 increases from 10%to 30%,The thermal expansion coe-fficient of the sealing material is reduced from 11.25×10-6K-11 to 11.15×10-6K-1,the seal-ing temperature is increased from 720?to 780?.The three sealing mate-rials are dense inside and have no elemental diffusion.Single cell test using Al2O3 as a 30%sealing mater-ial.The open circuit voltage of the single cell can reach 0.91V,the power density can reach380mW/cm2,and the sealing effect is better.In order to find a sealing material that is more in line with the GDC electrolyte SOFC.Therefore,on the basis of the Al2O3-SiO2-B2O3-Na2O-CeO2 system,10%,20%and 30%of CeO2 were compounded.The addition of CeO2 regulates the thermal expansion propert-ies of the sealing material.The thermal expansion coefficient increased from 11.30×10-6K-11 of composite 10%CeO2 to 11.45×10-6K-11 of composite 30%CeO2,the thermal expans-ion coefficient of composite 20%CeO2 is 11.42×10-6K-1.It is closer to the thermal expan-sion coefficient of the GDC electrolyte of 12×10-6K-1,and is suitable for sealing of the ele-ctrolyte.The use temperature of the sealing material was increased from 720?to 800?,the softening temperature of composite 20%CeO2 is 760?.The three composite sealing materials coexist with CeO2 for a long time at long-term use temperatures.Because the ho-les are too much in the composite 30%CeO2 sealing material when the temperature reach-es 750?or more.A 20%CeO2 single cell composite based on a base sealing material was used,which was used at a temperature of 760?and a thermal expansion coefficient of11.42×10-6K-1.The open circuit voltage of the battery can reach 0.96V,the power density can reach 384mW/cm-2,and the sealing effect of the composite sealing material is good. |
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