Recent advances in graphene-based phase change composites for thermal energy storage and management

Energy storage and conservation are receiving increased attention due to rising global energy demands.Therefore,the development of energy storage materials is crucial.Thermal energy storage(TES)systems based on phase change materials(PCMs)have increased in prominence over the past two decades,not only because of their outstanding heat storage capacities but also their superior thermal energy regulation capability.However,issues such as leakage and low thermal conductivity limit their applicability in a variety of settings.Carbon-based materials such as graphene and its derivatives can be utilized to surmount these obstacles.This study examines the recent advancements in graphene-based phase change composites(PCCs),where graphene-based nanostructures such as graphene,graphene oxide(GO),functionalized graphene/GO,and graphene aerogel(GA)are incorporated into PCMs to substantially enhance their shape stability and thermal conductivity that could be translated to better storage capacity,durability,and temperature response,thus boosting their attractiveness for TES systems.In addition,the applications of these graphene-based PCCs in various TES disciplines,such as energy conservation in buildings,solar utilization,and battery thermal management,are discussed and summarized.

Composition and Properties of Thermo-regulated Non-woven Fabrics

A series of non-woven fabrics were fabricated by blending S0- 80wt% of thennoregulated fibres containing n-elcosane, n-nonadecane or n-octadecane with 0 - 40wt% PET fibres and 0- 20wt% PP fibres. The phase change properties, thermal conductivity, thermal resistance, heat flux and inner temperature difference between wool felt and the thermoregulated non-woven fabrics of the non-woven fabrics were measured respectively. The thereto-regulated non-woven fabrics absorb heat at 25- 34℃ and release heat at 10- 25℃. The measured highest enthalpy of the non-woven is approximately 18J/g. During a heating process, heat flux of the non-woven fabrics is composed of three parts, heat absorbed by the cold textile touching the hot plate, heat transmitted from the hot plate to the cold plate, and the heat absorbed by PCM from the hot plate during the phase change process. The measured maximum inner temperature difference in a temperature rising process between the wool felt and the thermo-regulated non-woven fabric is approximately 8℃. The inner temperature difference （Tr-Ts〉0） lasts 16 - 45 min By contrary, the measured maximum inner temperature difference in the temperature decreasing process is approximately - 6. 5℃. The inner temperature difference （Tr-Ts〈0） lasts 16 - 50 min, The temperature regulation properties are obviously observed.

Reduced graphene oxide modified melamine sponges filling with paraffin for efficient solar-thermal conversion and heat management

A novel type of reduced graphene oxide(rGO)modified melamine sponges(rGS)filling with paraffin(rGS-pf)is developed for efficient solar-thermal conversion and heat management.The microstructures,filling and holding capacity of paraffin in porous rGS,solar-thermal energy conversion and energy harvesting efficiency of the prepared rGS-pf have been investigated systematically.The content of rGO nanosheets coated on the skeletons of rGS-pf is only 0.11%,while the loading content of paraffin in the rGS-pf is as high as 97.53%.Based on the solar-thermal conversion property of rGO nanosheets in the rGS-pf and the heat storage ability of paraffin in the rGS-pf,the proposed rGS-pf provides excellent performance for heat management.The efficiency of solar-thermal conversion could reach up to 92.5%.The thermo-regulation provided by the proposed rGS-pf is real-time,repeatable and long-term stable.The results in this study provide valuable guidance for developing functional materials for efficient solarthermal conversion and heat management.

Reshaping the imprinting strategy through the thermo-responsive moiety-derived“deep eutectic solvents”effect

As a new concept having emerged in last few years,the“deep eutectic solvents”(DESs)effect integrated into the imprinting technology inevitably exposes design limitations of stimuli-responsive molecularly imprinted polymers(MIPs),as well as inadequate analysis of the adsorption performance of MIPs.Herein,a simple yet defined N-isopropylacrylamide/(3-acrylamidopropyl)trimethylammonium chloride(NIPAM/APTMAC)binary DESs system was proposed to prepare intelligent MIPs with thermo-sensitivity.Accordingly,magnetic and thermo-responsive MIPs based on functional monomers-derived DESs(TMDESs-MIPs1)were synthesized,revealing DESs effect-regulated affinity/kinetics for the enhanced adsorption capability,eco-friendly thermo-regulated elution for high release efficiency,and simple magnetic separation,along with superior selectivity to rhein(RH)and good regeneration ability.TM-DESs-MIPs1 were utilized to extract RH from Cassiae semen samples coupled with high performance liquid chromatography(HPLC),yielding satisfactory recoveries(79.47%−110.82%)and low limits of detection(LOD)(16.67μg/L).Another two kinds of MIPs adopting the thermo-responsive moiety-derived DESs effect strategy further demonstrated great applicability of such intelligent MIPs for analyses of complicated samples.

Solar-absorbing metamaterial microencapsulation of phase change materials for thermo-regulating textiles

This paper presents a novel concept for designing solar-absorbing metamaterial microcapsules of phase change materials(PCMs)integrated with thermo-regulating smart textiles intended for coats or garments,especially for wear in space or cold weather on earth.The metamaterial is a periodically nanostructured metal-dielectric-metal thin film and can acquire surface plasmons to trap or absorb solar energy at subwavelength scales.This kind of metamaterial microencapsulation is not only able to take advantage of latent heat that can be stored or released from the PCMs over a tunable temperature range,but also has other advantages over conventional polymer microencapsulation of PCMs,such as enhanced thermal conductivity,improved flame-retardant capabilities,and usage as an extra solar power resource.The thermal analysis for this kind of microencapsulation has been done and can be used as a guideline for designing integrated thermo-regulating smart textiles in the future.These metamaterial microcapsules may open up new routes to enhancing thermo-regulating textiles with novel properties and added value.