Study On The Performance Of Direct Carbon Solid Oxide Fuel Cells Based On Anode Side Reaction Regulation

Direct carbon solid oxide fuel cell（DC-SOFC）is mainly composed of three parts:cathode,anode and electrolyte.As a new type of power generation device that is not limited by the Carnot cycle,it can efficiently and cleanly convert chemical energy from carbon fuels directly into electrical energy.It is expected to play an important role in achieving the"dual carbon"goal.However,there are multiple reaction paths and electron transfers in the electrochemical reaction process of DC-SOFC,resulting in a continuous decline in the output power and operating life of the battery.Serious constraints on the development of DC-SOFC.Therefore,this article intends to conduct research from three aspects:the development of new anode structures,high-performance Boudouard reaction catalysts,and new biomass carbon fuels.Improve the electrochemical performance and conversion efficiency of DC-SOFC to achieve efficient and stable operation.First,mesoporous silicon oxide modified nickel-based anode solid oxide fuel cell（SOFC）was prepared,and the performance of DC-SOFC was tested at 850°C with 5 wt.%Ba-loaded activated carbon as fuel.The results show that the maximum output power of the battery is 359 m W cm^-2,which is equivalent to the performance of traditional nickel-based anode SOFCs and has operated stably for 15.7 hours at a constant current of 50 m A.At the same time,the influence of anode porosity on mass transfer and electrochemical performance of DC-SOFC system was studied using numerical simulation technology.The results indicate that with the continuous increase of porosity,more O₂ and CO are consumed due to their participation in electrochemical reactions,and the performance of DC-SOFC is improved.The research results provide a new approach for the modification of traditional nickel-based anodes and a new method for developing new nickel-based anodes to improve the electrochemical performance of DC-SOFC.Secondly,from the perspective of improving the Boudouard reaction rate,carbon fuels loaded with different content of Mg based catalysts were successfully developed and applied to DC-SOFC to improve the electrochemical performance of the battery.Mg was loaded in the form of Mg CO₃ onto activated carbon using wet agglomeration technology,and the influence of different content of Mg based catalysts on the electrochemical performance of single cells was studied.The results showed that when with 5 wt.%Mg-loaded activated carbon fuel,DC-SOFC achieved the optimal electrochemical output of 172 m W cm^-2 at850°C,which was 72%higher than the single cell performance(100 m W cm^-2)with pure activated carbon fuel.Meanwhile,DC-SOFC was stably discharged at a constant current of50 m A for 58.3 hours,with a fuel utilization rate of 36.3%,while DC-SOFC with pure activated carbon fuel only discharged for 35.2 hours,with a fuel utilization rate of 11.5%.The electrochemical test results indicate that Mg is an excellent Boudouard reaction catalyst,which can effectively improve the Boudouard reaction rate and battery performance.The above results indicate that,the mechanism of carbon gasification catalyzed by Mg based catalysts was proposed,which provides a new approach for developing new Bourdouard reaction catalysts to achieve efficient and stable operation of DC-SOFC.Finally,three different biomass carbon fuels were developed to improve the electrochemical performance of DC-SOFC.The microstructure,graphitization degree,elemental composition and distribution of three types of biochar were analyzed using X-ray diffraction（XRD）,thermogravimetric analysis（TG）,scanning electron microscopy（SEM）,X-ray energy dispersive spectroscopy（EDS）,specific surface area desorption（BET）,and Raman spectroscopy（Raman）.The results showed that metal elements such as K,Ca,and Mg were present in all three types of biochar,These are excellent Boudouard reaction catalysts.Meanwhile,all three types of biochar have certain pore structures,which can increase the electrochemical reaction area,accelerate ion transport speed,and thus improve the electrochemical performance of the battery.The electrochemical test results showed that DC-SOFC using sesame straw biochar fuel exhibited the best electrochemical performance at 850°C,with a maximum output power of 227 m W cm^-2 and stable operation for 30.7hours at a constant current of 50 m A.The fuel utilization rate was 24.5%,which was superior to the battery performance and efficiency using the other two types of biochar fuels.The research results provide a new method for the efficient and clean utilization of biomass charcoal fuel,and a new approach for developing new types of biomass charcoal fuel to achieve efficient and stable operation of DC-SOFC.In summary,based on the research in this paper,the electrochemical performance and conversion efficiency of DC-SOFC have been optimized and improved,further promoting the development of DC-SOFC.