“…All samples have two characteristic peaks, namely, the D peak at 1349 cm –1 and the G peak at 1590 cm –1 . The D peak represents the A 1g vibration mode of disordered carbon, and the G peak is related to the E 2g vibration mode of sp 2 hybrid carbon in the graphite crystal region . Generally speaking, the lower the I D / I G value, the fewer the crystal defects of the carbon materials, which means a higher degree of graphitization. , The I D / I G values of all samples were calculated and are shown in Figure b.…”
Section: Resultsmentioning
confidence: 99%
“…This demonstrates that the SA/DCF-900 composite released the heat energy stored in the light-to-thermal conversion. The light-to-thermal conversion and energy storage efficiency (η) of the SA/DCF-900 composite can be calculated by the ratio of the heat storage of the SA/DCF-900 composite to the solar radiation energy collected during the phase transition. , The calculation formula is as followswhere m is the mass of the sample, Δ H m is the melting enthalpy of the sample, P is the illumination intensity of light source, S is the illumination area of the sample, and t 0 and t e are the start time and the end time of sample melting, respectively. According to formula , η of the composite is calculated to be 91.8%, while the light-to-thermal conversion efficiency of pure SA is 0% without undergoing phase transition during the radiation time.…”
Section: Resultsmentioning
confidence: 99%
“…conversion. The light-to-thermal conversion and energy storage efficiency (η) of the SA/DCF-900 composite can be calculated by the ratio of the heat storage of the SA/DCF-900 composite to the solar radiation energy collected during the phase transition 6,50. The calculation formula is as follows…”
For enhancing the heat storage and encapsulation performances
of
organic phase change materials (PCMs), a carbon foam (CF) with a continuous
dual-scale pore structure (DCF) was developed. Employing the as-prepared
DCF as a stearic acid (SA) support, a novel shape-stabilized SA–CF
composite PCM with a continuous dual-scale interpenetrating network
structure was achieved through the impregnation of SA into the DCF.
DCF-900, prepared at an activation temperature of 900 °C, possesses
a high loading capacity of 89.54 wt % for melted SA without leakage.
The resulting SA/DCF-900 composite with a continuous dual-scale interpenetrating
network structure exhibits excellent comprehensive performances with
a good synergistic effect. The composite presents a thermal conductivity
of 1.298 W/m·K and an encouraging compressive strength of 9.03
MPa, which increase by 2.25-fold and 3.56-fold compared with those
of DCF-900, respectively. Furthermore, its melting and freezing enthalpies
reach 192.8 and 192.7 J/g with a storage efficiency of about 100%,
respectively; meanwhile, it displays excellent thermal cycle stability
and reversibility after 600 thermal cycles with a high melting/freezing
enthalpy retention rate of up to 96%. More importantly, its light-to-thermal
conversion efficiency reaches 91.8% under a light intensity of 100
mW/cm2. Consequently, the SA/DCF-900 composite is a promising
candidate for high-performance PCMs.
“…All samples have two characteristic peaks, namely, the D peak at 1349 cm –1 and the G peak at 1590 cm –1 . The D peak represents the A 1g vibration mode of disordered carbon, and the G peak is related to the E 2g vibration mode of sp 2 hybrid carbon in the graphite crystal region . Generally speaking, the lower the I D / I G value, the fewer the crystal defects of the carbon materials, which means a higher degree of graphitization. , The I D / I G values of all samples were calculated and are shown in Figure b.…”
Section: Resultsmentioning
confidence: 99%
“…This demonstrates that the SA/DCF-900 composite released the heat energy stored in the light-to-thermal conversion. The light-to-thermal conversion and energy storage efficiency (η) of the SA/DCF-900 composite can be calculated by the ratio of the heat storage of the SA/DCF-900 composite to the solar radiation energy collected during the phase transition. , The calculation formula is as followswhere m is the mass of the sample, Δ H m is the melting enthalpy of the sample, P is the illumination intensity of light source, S is the illumination area of the sample, and t 0 and t e are the start time and the end time of sample melting, respectively. According to formula , η of the composite is calculated to be 91.8%, while the light-to-thermal conversion efficiency of pure SA is 0% without undergoing phase transition during the radiation time.…”
Section: Resultsmentioning
confidence: 99%
“…conversion. The light-to-thermal conversion and energy storage efficiency (η) of the SA/DCF-900 composite can be calculated by the ratio of the heat storage of the SA/DCF-900 composite to the solar radiation energy collected during the phase transition 6,50. The calculation formula is as follows…”
For enhancing the heat storage and encapsulation performances
of
organic phase change materials (PCMs), a carbon foam (CF) with a continuous
dual-scale pore structure (DCF) was developed. Employing the as-prepared
DCF as a stearic acid (SA) support, a novel shape-stabilized SA–CF
composite PCM with a continuous dual-scale interpenetrating network
structure was achieved through the impregnation of SA into the DCF.
DCF-900, prepared at an activation temperature of 900 °C, possesses
a high loading capacity of 89.54 wt % for melted SA without leakage.
The resulting SA/DCF-900 composite with a continuous dual-scale interpenetrating
network structure exhibits excellent comprehensive performances with
a good synergistic effect. The composite presents a thermal conductivity
of 1.298 W/m·K and an encouraging compressive strength of 9.03
MPa, which increase by 2.25-fold and 3.56-fold compared with those
of DCF-900, respectively. Furthermore, its melting and freezing enthalpies
reach 192.8 and 192.7 J/g with a storage efficiency of about 100%,
respectively; meanwhile, it displays excellent thermal cycle stability
and reversibility after 600 thermal cycles with a high melting/freezing
enthalpy retention rate of up to 96%. More importantly, its light-to-thermal
conversion efficiency reaches 91.8% under a light intensity of 100
mW/cm2. Consequently, the SA/DCF-900 composite is a promising
candidate for high-performance PCMs.
Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation. Featured by its exceptional thermal conductivity, graphene is an ideal functional filler for fabricating thermally conductive polymer composites to provide efficient thermal management. Extensive studies have been focusing on constructing graphene networks in polymer composites to achieve high thermal conductivities. Compared with conventional composite fabrications by directly mixing graphene with polymers, preconstruction of three-dimensional graphene networks followed by backfilling polymers represents a promising way to produce composites with higher performances, enabling high manufacturing flexibility and controllability. In this review, we first summarize the factors that affect thermal conductivity of graphene composites and strategies for fabricating highly thermally conductive graphene/polymer composites. Subsequently, we give the reasoning behind using preconstructed three-dimensional graphene networks for fabricating thermally conductive polymer composites and highlight their potential applications. Finally, our insight into the existing bottlenecks and opportunities is provided for developing preconstructed porous architectures of graphene and their thermally conductive composites.
“…The continuous 3D graphene skeleton can provide accelerated heat transfer channels for PCMs. 104 Therefore, GAs can greatly reduce the internal contact thermal resistance in their continuous 3D architectures. For example, Zhong et al 105 developed octadecanoic acid (OA)@GA composite PCMs with tightly integrated interfaces due to the good wettability between the two phases.…”
Benefiting from the inherent properties of ultralight weight, ultrahigh porosity, ultrahigh specific surface area, adjustable thermal/electrical conductivities, and mechanical flexibility, aerogels are considered ideal supporting alternatives to efficiently encapsulate phase change materials (PCMs) and rationalize phase transformation behaviors. The marriage of versatile aerogels and PCMs is a milestone in pioneering advanced multifunctional composite PCMs. Emerging aerogel-based composite PCMs with high energy storage density are accepted as a cutting-edge thermal energy storage (TES) concept, enabling advanced functionality of PCMs. Considering the lack of a timely and comprehensive review on aerogel-based composite PCMs, herein, we systematically retrospect the state-of-the-art advances of versatile aerogels for high-performance and multifunctional composite PCMs, with particular emphasis on advanced multiple functions, such as acoustic−thermal and solar−thermal−electricity energy conversion strategies, mechanical flexibility, flame retardancy, shape memory, intelligent grippers, and thermal infrared stealth. Emphasis is also given to the versatile roles of different aerogels in composite PCMs and the relationships between their architectures and thermophysical properties. This review also showcases the discovery of an interdisciplinary research field combining aerogels and 3D printing technology, which will contribute to pioneering cutting-edge PCMs. This review aims to arouse wider research interests among interdisciplinary fields and provide insightful guidance for the rational design of advanced multifunctional aerogel-based composite PCMs, thus facilitating the significant breakthroughs in both fundamental research and commercial applications.
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