Preparation Of Yeast-based Biomass Carbon Material And The Application Research Of Electrochemical Energy Storage

With the decreasing of fossil resources and the worsening of ecological environment,looking for low-cost and clean sustainable energy and studying efficient energy storage systems are the social urgent issues to be settled.Supercapacitor with the merits of quick charging,long life,high power density,and green is a new energy storage device.Lithium-sulfur batteries for abundant,cheap,safe and high specific capacity have been considered to be one of the most potential of future high-energy density lithium ion secondary batteries.Furthermore,biomass-based carbon materials have been widely considered as the ideal electrode materials of supercapacitors and lithium-sulfur batteries,due to low price,abundant source,high conductivity,plentiful pore and controllable pore size.In this paper,from the reducing cost and environmental protection point of view,using low-cost yeast cells as precursor through the pretreatment,the chemistry activated process and high-temperature pyrolysis methods,we synthesized a series of nitrogen-doped biomass derived carbon with various morphologies and high specific surface area.And then we prepared the cathodes by mixing these carbon materials and sulfur and deeply explored the electrochemical performance of the batteries.In addition,the prepared biomass-based carbon materials were used as the electrode materials for supercapacitors and the electrochemical performances were talked about.The research contents and results in detail are listed in the following.（1）A series of nitrogen-doped porous biomass-based carbon materials（NHCM）from yeast cells as precursor have been prepared by a simple chemical activated method with K₂CO₃.The biomass-based carbon material with nitrogen content of1.78 wt%has a high specific surface area（2150 m²/g）and pore volume（1.41cm³/g）.The carbon/sulfur composite（NYMC/S）with melting method delivers a high specific capacity of 1410 mAh/g and remains a high capacity retention of 912mAh/g after 200 cycles.（2）The elliptical hollow nitrogen-doped porous carbon microspheres（NHPCM）from yeast cells as self-template have been synthesized through the hydrothermal process with the introduction of a percentage of glutaraldehyde and heat-treatment process.The NHPCM material has a high specific surface area of 712 m²/g and exhibits enriched micro/mesoporous structure in the carbon shell.Due to the pyrolysis of protein,the self-doped nitrogen content reaches up to 9.08 wt%,especially the graphitic and pyridinic nitrogen can obviously suppress the shuttle effect of polysulfides.The NHPCM@S composite with sulfur loading of65 wt%as the cathode of Li-S battery shows superior cycling performance.The battery firstly delivers a discharge capacity of 1202 mAh/g and the capacity retention remains to be 60.3%within 400 cycles at 0.1 C.（3）Using yeast as carbon source,multiporous biomass-based carbon materials have been synthesized through the hydrothermal and K₂CO₃ activation at different temperatures as the electrode materials for supercapacitors.The relation of pore size and specific surface area on the specific capacity has been probed.The results show the electrochemical performance of the yeast-based carbon electrode material at800°C is best than others at different temperatures.Its specific capacitance is 246.3F/g at a current density of 1 A/g and the capacitive retention ratio is 87.95%after5000 cycles,which exhibits good cycling stability.