Research On Preparation Of Carbon Aerogel-based Composite Phase Change Materials And Their Photo-thermal Energy Storage Properties

With the burning of a colossal amount of non-renewable energy sources such as coal and oil,the fuel poverty has become one of the major challenges facing mankind in the 21st century.In recent years,the emergence of thermal energy storage（TES）technology has resolved the mismatch between thermal energy provision and requirement in time and space,and plays an important role in energy conservation.Latent heat storage technology which phase change materials（PCMs）as the kernel is the most prospective TES technology for development and application.And phase change composites（PCCs）with lofty latent heat,great thermal conductivity and shape stability are of great significance to realize efficient photo-thermal conversion and energy storage.Based on this,porous carbon materials with high thermal conductivity was selected as a matrix for loading paraffin wax（PW）to make shape-stabilized phase change composites（ss-PCCs）.Meanwhile,the chemical structure,morphology,shape stability,thermal and physical properties,photo-thermal conversion and storage performance were also investigated.（1）CMPA and CMPCA were prepared by Sonogashira-Hagihara coupling reaction,and then PW was loaded by vacuum-assisted melting impregnation method to obtain CMPA@PW and CMPCA@PW with paraffin loading up to 1389 wt%and1206 wt%,respectively.Both kinds of ss-PCCs have high energy storage density,low degree of undercooling,excellent shape stability,thermal stability,thermal cycling stability and long-term chemical stability.Moreover,CMPCA has a thermal conductivity of 0.29 W·m^-1·K^-1 and a strong light absorption of about 85%in the entire UV-Vis-NIR range,which endowed CMPCA@PW better thermal conductivity,light absorption and 91.99%photo-thermal conversion and energy storage efficiency.（2）Graphene aerogels（GA）and a series of nanofibrillated cellulose/graphene aerogels（NGA）were synthesized by hydrothermal and freeze-drying methods using tannic acid（TA）as the reducing agent and nanofibrillated cellulose（NFC）as the mechanical property enhancer.And paraffin wax then was loaded by vacuum assisted melt impregnation to obtain PCC₀,PCC_0.5,PCC₁,PCC_1.5,PCC₂ and PCC_2.5.The results show that the addition of NFC to GA can effectively improve the shape stability of the PCCs,and NGA_2.5 has the highest PW loading rate which can adsorb31.58 times of its own weight.PCC_2.5 has excellent shape stability,thermal stability and thermal cycling stability,with a high latent heat of 147.9 J/g.