Preparation And Properties Of Novel Hybrid Carbon Aerogel-based Composite Phase Change Materials

Thermal-energy storage technology is considered as an effective approach to solve the problem of energy shortage and environmental pollution.In particular,phase-change energystorage technology has received widespread attention because they have the characteristics of easy operation,extinctive heat-storage capacity and so on.This technology stores and releases thermal energy by using phase change materials,which have the advantages of high energy storage capacity,proper phase change temperature and small volume change.However,phase change materials still possess much defects such as easy leakage and poor thermal conductivity,which seriously limit their scale applications.Therefore,this thesis prepared novel composited phase change materials based on hybrid carbon aerogel,and their thermal conductivity,photo-thermal performance and heat storage property were further researched.The specific research content is as follows:(1)Novel hybrid carbon aerogels with lightweight,compressible and resilient performance were prepared through assembly and enhancement between MnO2 and biomass guar gum.MnO2 nanorods were uniformly attached on the surface of the aerogel,which were used to enhance the hybrid carbon aerogel due to its excellent optical performance and structure superiority.Then,phase change materials were further encapsulated by the carbon aerogel to fabricate composite phase change materials,which exhibited good shape and thermal stability.Their latent heat reached 174-179 J/g and thermal conductivity increased by 153% compared with pure PEG8000.MnO2 nanorods also endowed the composite phase change materials with high photo-thermal conversion efficiency of 82%,which showed broad application prospects in solar energy utilization.(2)This study proposed to fabricate novel BMNs/Ni/C hybrid carbon aerogels by taking advantage of good multi-porous structure of Ni-MOF and high thermal conductive BNNs through structure design and assembly.The carbon aerogel was used to encapsulate hexadecylamine,obtaining novel composite phase change materials with high performances.The composite phase change material showed outstanding phase change properties with a high phase-change enthalpy of 272.74 J/g,which had almost no change after 200 thermal cycles.Furthermore,the synergistic effect of Ni nanoparticles and BNNs effectively enhanced the thermal conductivity,which increased by 187% as compared with pure hexadecylamine,and also provided the composites with high photo-thermal conversion efficiency of 89.6%.(3)Novel composite phase change materials with good comprehensive performances were constructed by using low cost and long chains biomass cellulose as flexible carbon resource,polyvinyl alcohol as a carbon aerogel skeleton,and thermal conductive BNNs as nano-reinforcement units.The composite phase change materials showed excellent thermal stability and good energy-storage performance,which had a phase-change enthalpy in the range of 160.88-165.76 J/g.And their thermal conductivity improved by 61.3% compared with that of pure phase change material.Besides,their photothermal conversion efficiency can reach 84.5%.