Composite Phase Change Research Articles

The spider web of modified wheat bran captured PEG to form stabilized phase change composites for temperature regulation and waste heat storage

Biomass based phase change composites (PCCs) have potential application prospects in the field of thermal energy storage (TES). Environmentally friendly development could be realized by recycling and reusing wheat bran (WB) of the agricultural and forestry waste. Distinguished from conventional biomass derivatives and/or carbonization methods, multi-walled carbon nanotubes (MWCNT/OH) modified wheat bran aerogels (MWB) with 3D entanglement structure was fabricated by utilizing physical pasting incorporating chemical cross-linking and functional modification, and then followed by freezing method. The fabricated MWB exhibited a graded and “spider web” entangled special porous structure, which could adsorb polyethylene glycol (PEG) effectively to form stabilized PCCs (MWB/PEG). This non‑carbonized, thermally conductive biomass PCCs play a positive role in energy and environmental recycling. Experimental results indicated that MWB possessed 87.9 % adsorption efficiency and excellent anti-leakage property. Enthalpy efficiency embodied through thermal storage capacity reached 86.5 %. Besides, the outstanding temperature regulation and heat transfer characteristics were verified by thermal infrared imaging. Two clear phase transition buffers appeared as well as the temperature distribution mainly concentrated in the phase transition temperature range from vertical view during heating/cooling process. Thermal conductivity and thermal diffusion coefficient of MWB/PEG increased to 0.26 W/m·K and 0.19 mm2/s from 0.15 W/m·K and 0.11 mm2/s for pure PEG, respectively. The MWB/PEG could store thermal energy by illumination and corresponding photothermal conversion rate reached up to 80.4 %. This composite showed a remarkable waste heat storage and/or reuse through electrothermal testing with integrated conductive fabrics, which would provide a potential development of green and high performance of TES technology in wearable flexible sensors and other fields.

Thermal energy storage characteristics of carbon-based phase change composites for photo-thermal conversion

Capture and utilization of solar energy using phase change materials (PCMs) can effectively answer the challenge of solar intermittency. However, the flaws of low thermal conductivity and poor thermal stability of PCMs limit their practical applications, and the selective absorption of solar energy also hinders it to achieve high photo-thermal conversion. In this work, a novel PCM was synthesized by adding expanded graphite and olefin block copolymers blended within paraffin wax. Enhanced thermal conductivities were realized that a 17.12 W/(m·K) in the vertical compression direction and 4.71 W/(m·K) in the parallel compression direction, which were 68.48 and 18.84 times in contrast to that of raw paraffin wax. A maximum solar absorptance of 97.47 % was achieved, and the photo-thermal conversion and energy storage capacity in the vertical compression direction were superior using the novel PCM. With the increase in light intensity, this PCM completed phase transition faster, reached a higher equilibrium temperature, and exhibited an outstanding thermal stability and cyclic stability within the assisted electron conductivity. Additionally, commercial software was also used to simulate thermoelectric applications of the PCM in real-world settings. This study provides new ideas for preparation and solar-thermal applications of anisotropic carbon-based PCMs.

Enhanced thermal conductivity of phase change composites with novel binary graphite networks

The thermal conductivity and porous structure of carbon-based networks significantly affect the heat exchange efficiency in phase change composites. However, simultaneously improving its thermal conductivity and controlling the formation of micrometer-scale open pores remains a significant challenge. In this study, a binary graphite network is constructed by both high-thermal-conductivity mesophase-pitch carbon fibers and high-textured pyrolysis carbon through chemical vapor deposition and ultra-high temperature graphitization, then embed paraffin to form high-performance phase change composites. The characteristic hierarchical pore structure in the binary graphite network facilitating the paraffin impregnation and its heat exchange efficiency is greatly improved by showing an optimum thermal conductivity of 144.78 W·m−1·K−1 and a phase change enthalpy of 87.4 J·g−1 at 0.6 g·cm−3 graphite skeleton and 51 wt% paraffin. The developed phase change composites hold great application potential in thermal control for space optical-mechanical systems and other critical aerospace components.

Natural Fibrous Materials Based on Fungal Mycelium Hyphae as Porous Supports for Shape-Stable Phase-Change Composites.

Adsorption of organic phase-change materials (PCMs) by the porous matrix of microfibrillar cellulose (MFC) is a simple and versatile way to prepare shape-stable phase-change composites, which are promising as sustainable thermoregulating additives to construction materials. However, due to MFC inherent morphology, the resulting composites have relatively low poured density that complicates their introduction in sufficient amounts, for instance, into mortar mixes. Unlike MFC, fungal mycelium has, by an order, less fibrils thickness and, thus, possesses significantly higher poured density. Herein, we studied the feasibility of fungal mycelium-based matrices as alternative biopolymeric porous supports for preparation of sustainable and shape-stable phase-change composites. Two methods were employed to prepare the porous mycelium-based supports. The first one was the solid-state fermentation, which resulted in partial biotransformation of MFCs to mycelium hyphae, while the second one was the liquid-state surface fermentation, used to cultivate the reference matrix of Trametes hirsuta hyphae. The phase-change composites were prepared by adsorption of model organic PCMs on porous biopolymer matrices. The mass ratio of support/PCM was 40/60 wt%. The composites were studied with respect to their structure, composition, poured density, latent heat storage properties, and thermal and shape stability. The employment of the partially transformed to mycelium-hyphae MFC fibers was found to be a suitable way to prepare phase-change composites with improved poured density while preserving a reasonable latent heat capacity and shape stability as compared to the MFC/PCM composites.

Microstructure and mechanical properties of phase change cloud concrete stone cementitious composites

In this study, a novel kind of phase-change cementitious composites with cloud concrete stone (CCS) as aggregate were prepared and studied. The CCS was synthesized with fly ash, slag, and other construction waste through water heat and autoclaving. The phase-change paraffin was absorbed into the CCS using the vacuum impregnation technique, and then the epoxy resin combined with cement powder was applied to the aggregate surface to prevent the leakage of phase-change materials (PCMs). The composite aggregate with phase change function was, thus, fabricated. A series of experiments were carried out to study and evaluate the molecular structure, physical phase, and phase transition temperature of encapsulated composite aggregate with the means of Fourier infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The PCM-cement composites were prepared by replacing coarse aggregates with the composite aggregate in proportions of 25%, 50%, 75%, and 100% in volume. To explore the strength degradation in view of the microscopic perspective, scanning electron microscopy (SEM), XRD, and Image-Pro-Plus (IPP) were used. The experimental results revealed that the effect of the micropores of CCS on the melting temperature of the phase-change aggregates (24.84 °C) is higher than that of the paraffin (22.91 °C). The mechanical experiments results demonstrated that the compressive strength and splitting strength losses in the PCM-cement composite with replacement ratios of 75% were 24% and 39%, respectively. The XRD results revealed that with the incorporation of PCM, the calcium silicate hydrate (C-S-H) in the hydration products decreased and the Ca/Si value in C-S-H decreased from 9.05 to 2.13, which is one of the reasons for the strength decline of the PCM-cement composites. The cracks in the interfacial transition zone between the aggregate and matrix became large with increasing admixture, and the pore characteristics gradually became more apparent. The strength of the PCM-cement composite decreased with the increase in the average porosity, pore size, and perimeter of the matrix material.

Facile, catalyst-free, and high enthalpy PEG-based phase change composite for use in photothermal conversion and waste heat recovery

The poor shape stability, low thermal storage density, and complex process confronted in fabricating high-performance phase change composites (PCCs) via the chemical cross-linking technology. Herein, PEG-based shape stability PCC (SSPCC) with high enthalpy and good shape stability was obtained using a facile one-pot method without additional catalysts. The reliable three-dimensional cross-linked structure formed by the interaction of epoxy resin and curing agent binds the movement of PEG molecular chains, which simultaneously in coupled with the stronger hydrogen bonding between PEG and cross-linked products to endow the as-prepared SSPCC with excellent shape stability, thermal stability, durability, and high thermal storage density (160.8 J/g). Moreover, the Raman spectra clearly presented the interaction force and phase morphology distribution between PEG and the skeleton structure. SSPCC with the high relative enthalpy efficiency and melt enthalpy can play an essential role in photothermal applications, while the facile manufacturing process free from additional organic solvents or high temperature, highlighting its green and sustainable features. Additionally, the photothermal transport and thermostatic effects of the SSPCCs show great potential for application in waste heat recovery, which can maintain higher temperatures for a long time. Totally, such SSPCC with reliable and distinguished phase change properties ensure a wide range of potential applications, while the easy-to-prepare and low-cost fabrication method provides an inspiring strategy for alternative SSPCC development.

Ti3C2Tx MXene/delignified wood supported flame-retardant phase-change composites with superior solar-thermal conversion efficiency and highly electromagnetic interference shielding for efficient thermal management

The development of form-stable phase-change material (PCM) with solar-thermal harvest, electromagnetic interference (EMI) shielding, and flame-retardancy is crucial for efficient building energy management and conservation. Herein, novel Ti3C2Tx MXene/delignified wood supported form-stable phase-change composites (PMPCMs) with superior solar-thermal conversion efficiency, highly EMI shielding effects, and excellent flame-retardancy were fabricated by alkaline boiling delignification, ammonium dihydrogen phosphate (ADP) and MXene deposition, and melted n-octadecane impregnation. Benefiting from the powerful surface tension and capillary force of the wood-based support materials, PMPCMs can effectively encapsulate the melted n-alkane molecules and inhibit their leakage. The differential scanning calorimetry results showed that PMPCMs possessed superior n-octadecane encapsulation yield and high thermal energy storage density (166.9–191.6 J/g). Decorating delignified wood by MXene significantly improved the solar-thermal storage efficiency (up to 88.4 %) and EMI shielding performance of PMPCMs. The average EMI shielding effectiveness of PMPCM-10 was enhanced to 34.12 dB in X-band frequency range of 8.2–12.4 GHz. Moreover, with the introduction of the flame-retardant ADP, the peak heat release rate (pHRR) and total heat release (THR) of PMPCMs decreased noticeably, demonstrating the enhanced flame retardancy of delignified wood supported phase-change composites. In summary, PMPCMs exhibited superior application prospects in building energy management and electromagnetic shielding fields.

Synthesis and Thermal Characterization of Solar Salt-Based Phase Change Composites with Graphene Nanoplatelets

Synthesis and Thermal Characterization of Solar Salt-Based Phase Change Composites with Graphene Nanoplatelets

Experimental and Numerical Investigations on Flexible Paraffin/Fiber Composite Phase Change Material

Abstract A flexible paraffin/hollow fiber phase change composite was prepared using a simple impregnation method, and the thermal-release performance of a piece of woven paraffin/hollow fiber rectangular blocks was systematically investigated using experimental and numerical methods. The experimental results of the thermal-release performance were highly consistent with the numerical results. Consequently, the thermal-release performance, including the available energy and solidification time, of the paraffin/hollow fiber with different melting temperatures, mass fractions (corresponding to the enthalpy), specific heat, and thermal conductivity were numerically investigated. The available energy of the paraffin/hollow fiber completely depends on the mass fraction of the paraffin. The solidification time mainly depends on the mass fraction of the paraffin and secondarily on the thermal conductivity, while the specific heat has little effect on the solidification time. Therefore, the thermal-release performance of the paraffin/hollow fiber could be optimized through numerical simulation by altering the solidification temperature, mass fraction, thermal conductivity, and specific heat.

An innovative graphene-based phase change composite constructed by syneresis with high thermal conductivity for efficient solar-thermal conversion and storage

Graphene-based phase change composites hold significant potential for solar energy utilization, but their poor thermal conductivity hinders their practical applications. In this work, an air-dried graphene skeleton (AGS) with excellent thermal conductivity enhancement efficiency was constructed by the ice templating method and syneresis, and the air-dried graphene phase change composite (AGP) was subsequently obtained through vacuum-impregnating n-Docosane (C22) into AGS. The syneresis effectively reduced the phonon scattering between graphene sheets within AGS and increased the density of AGS to 0.1701 g/cm³. Therefore, with a graphene skeleton loading of 23.82 wt.%, AGP exhibited excellent thermal conductivity of 9.867 W/(m K), outstanding electrical conductivity of 68.08 S/cm, and remarkable shape stability. Additionally, AGP demonstrated a melting enthalpy of 188.5 J/g and an outstanding solar-thermal conversion efficiency of 93.98%, showing enormous potential for the utilization of solar energy.

Energy storage and key derives of octadecane thermal stability during phase change assembly with animal manure-derived biochar

The design of eco-friendly and renewable energy infrastructure is highly desirable to advance the global energy landscape. Phase-change materials (PCMs) are used to mitigate intermittency issues and reversibly store high densities of thermal energy in the form of heat during the phase transition process and provide ample potential for the advancement of renewable energy infrastructure. However, the leakage and low thermal stability of pristine PCMs along with the complicated synthesis strategies and environmental issues of the supporting materials cause significant drawbacks, thereby requiring a sustainable confining agent. In this study, a green phase change composite was developed using biowaste-derived biochar and octadecane via a vacuum impregnation strategy. The structural, morphological, thermal, and shape stabilities, as well as the chemical compatibilities of both the composite components and the octadecane-biochar composite, were investigated. The supporting biochar provides sufficient physical and thermal support besides high encapsulating capacity due to high specific surface area (135.2 m2 g−1) and predominant mesoporous proportion (86%). The results displayed that the composite material revealed a high leakage-proof capability (above the melting point of pure octadecane) with a low leakage rate (<12.5%) for a long heating time, excellent thermal stability, and high latent heat retention (89.5%) after 1000 heating–cooling cycles. The fabricated composite attained satisfactory phase change enthalpy storage, which was 130% and 168.9% higher than that of rice-husk-paraffin and garlic peel-derived carbon-paraffin, respectively, indicating promising thermal management performance. This study opens avenues for the development of green composite materials and renewable energy storage and conversion, which will play a significant role in various sectors such as building energy-saving and heat recovery systems.

Thermophysical properties and solar thermal energy storage performance of phase change composites manufactured by vat photopolymerization 3D printing technique

Phase change materials (PCMs) refer to a group of semi-solid/liquid materials that have high energy storage capacity that are released during the phase transitioning period. Although the impact of utilizing PCMs are considerable, often suitable conservation from leakage is a major issue for these materials' uses. Considering this issue, this study incorporates a Vat Photopolymerization technique to print a composite resin filament containing lauric acid (LA) used as a PCM. LA were mixed with resin in four different proportions of 20, 30, 40 and 50 vol%, and then printed for testing. To thoroughly analyze the characteristics of the resin/LA composites that were manufactured, a range of tests focusing on mechanical, thermal, and microstructural aspects were carried out on the produced samples. Additionally, solar thermoregulation properties were also investigated using a specifically developed testing instrument. The obtained results show that the highest latent heat enthalpy value (83.7 J/g) was found in 50 % LA added composites that also contained a homogeneous internal structure compared to undoped resin materials. Although 50 % LA additive provides superior heat energy storage, it causes a decrease in mechanical properties, since the resin has five times higher tensile strength than that of LA. Nonetheless, the results show that PCMs (specifically LA, in this case), can be 3D printed in real-time with resins without concerns over the leakage problem. This novel use of PCMs can significantly improve the leaking issue and provide a solid mean for energy storage purposes that can support major insulating and energy savings.

Corn straw supported high-performance phase change composites: Strategy to turn agricultural residues into high efficient and stable thermal energy storage materials

Using polypyrrole (PPy)-coated agricultural corn straw (CS) as support frameworks, polyethylene glycol (PEG) as phase change components, a shape-stable phase change thermal storage composite (CS@PPy-PEGx) was obtained by simple crosslinking, melt-blending, and freeze-drying processes. With the help of potential non-covalent interactions among each component (e.g., hydrogen bonding), the encapsulation of PEG in these composites reached as high as 90 wt%, and displayed-enhanced thermal conductivities (a maximum of ∼0.22 W/(m·K)), thermal reliabilities and stabilities (with no obvious shape deformation after 100 heating and cooling cycles), promising thermal storage capacities (with max latent melting heat of ∼145.80 J/g and crystallization heat of ∼141.50 J/g), as well as conducive leakage resistance. Thus, this study paved a green and feasible strategy to convert agricultural straw residues into shape-stable and high-performance phase change composites that demonstrated great potential in the field of building thermal energy storage.

Thermal Interface Engineering in a 3D-Structured Carbon Framework for a Phase-Change Composite with High Thermal Conductivity.

Phase-change materials (PCMs) are promising thermal storage medium for thermal management due to their efficient thermal energy harvesting capabilities. However, the low thermal conductivity (TC) and poor shape stability of PCMs have hindered their practical applications. Construction of an interconnected three-dimensional (3D) heat-conductive structure is an effective way to build phonon conduits and provide PCM confinement. Phonon scattering at the interface is an unavoidable effect that undermines the TC improvement in the PCM composite and necessitates careful engineering. This study focuses on creating a highly thermally conductive 3D carbon-bonded graphite fiber (CBGF) network to enhance the TC of the PCM, with attention especially on thermal interface engineering considering both filler-matrix (F-M) and filler-filler (F-F) interfaces. The composite with an optimized proportion of F-M and F-F interface area achieves the highest TC of 45.48 W·m-1·K-1, which is 188.5 times higher than that of the pure PCM, and a high TC enhancement per volume fraction of the filler (TCEF) of 831% per 1 vol % loading. This also results in an enhanced spatial construction for PCM confinement during the phase change. The results emphasize the significance of interface engineering in creating high-TC and form-stable phase-change composites, providing insightful guidance for rational structural design.

Flexible highly thermally conductive biphasic composite films for multifunctional solar/electro-thermal conversion energy storage and thermal management

Phase change materials (PCMs) have been widely used for thermal energy storage in overcoming the intermittence of renewable energy and passive thermal management. However, low thermal conductivity, leakage, inherent brittleness, and lack of responses under multiple stimuli preclude their widespread applications. Here, we report a flexible and form-stable solid-solid/solid-liquid biphasic phase change composites to achieve efficient solar/electro-thermal energy conversion and storage as well as thermal management of high-power devices simultaneously. Proposed biphasic polyurethane–stearic acid/expanded graphite (PU–SA/EG) composites demonstrate state-of-the-art performances with a high energy storage density of 117.4–137.3 J/g and high thermal conductivity of 10.98–37.80 W/(m⋅K) simultaneously at an EG loading ratio of 10–30 wt %, benefiting from the formation of continuous thermal transport network provided by expanded graphite nanosheets. PU–SA/EG maintains high flexibility and good thermal reliability over more than 500 melting/solidification cycles. High solar- and electro-thermal conversion and storage efficiencies of up to 90.5% and 88.7% are achieved, respectively. When applied in thermal management of flexible electronic devices, PU–SA/EG film demonstrates a superior cooling performance by reducing device temperature prominently by 32 °C under a DC 5A discharging power supply. This work provides an effective way for harvesting and storing multiple energy sources like solar energy and electricity, as well as thermal management of high-power electronic devices.

Constructing interfacial barrier from tribo-positive shell microcapsules to suppress space charge in thermochromic phase change composites for smart electronics

Thermochromic phase change composites (TPC) exhibit versatile functions under electrothermal stimuli, which are extensively applied as packaging, insulation and circuit components in considerable advanced smart electronics. However, space charge accumulation under DC voltages is still a critical and universal issue for the serious deterioration of functionalities and life-span of TPC and electronics. This study presents a novel strategy of suppressing space charge in thermochromic phase change epoxy composites (TPCE) by constructing interfacial barrier from tribo-positive shell thermochromic phase change microcapsules. The strong tribo-positive melamine-formaldehyde (MF) shell of microcapsules can establish negative charge barriers in the interfaces between microcapsules and epoxy matrix through triboelectrification, which is directly verified by Kelvin probe force microscopy. Pulsed electroacoustic measurement results exhibit the space charge accumulation in TPCE under an extreme electric field strength of 50 kV/mm and an elevated temperature of 70 °C can be significantly diminished by 39.3% compared to that of neat epoxy resin after incorporating merely 1 phr MF shell microcapsules, affirming the effect of interfacial barrier on space charge inhibition. The interfacial barrier could improve the charge carrier dissipation and mitigating the space charge accumulation as confirmed by hopping conduction analysis. Moreover, DC breakdown strength of TPCE can also be enhanced by 12.3% and 6.1% with 1phr microcapsules at 30 °C and 70 °C compared to that of neat epoxy resin owing to the suppressed space charge. The results provide a potential approach of designing high-performance thermochromic phase change composites for smart electrical and electronic devices.

Designing Poly(3,4-ethylenedioxythiophene) Polystyrene Sulfonate/Graphene Oxide/Graphene Nanosheet/Polyethylene Glycol Phase-Change Composites with Superior Thermal Management for Photo-thermoelectric Generators.

Recently, growing interest in self-powered devices has led to the invention of new energy conversion devices. Photo-thermoelectric generators (PTEGs) have rapidly developed for their ability to harvest both light and thermal energy, but these devices are overly dependent on the continuity of energy input and cannot sustain output in an emergency situation. In the current study, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/graphene oxide (GO)/graphene nanosheets (GNPs)/polyethylene glycol (PEG) phase-change composites (PCCs) were prepared with freeze-drying and vacuum-filling processes to acquire materials suitable for imparting energy storage characteristics to PTEGs. The melting and crystallization enthalpies of the PCCs fabricated based on the PEDOT:PSS/GO/GNP aerogels can reach 211.5 and 207.6 J g-1, respectively, which increase by nearly 5% compared with pure PEG, and the growth rate of thermal conductivity of the composites is as high as 262.7% (1.12 W m-1 K-1). Meanwhile, the excellent photothermal properties and high-temperature shape stability that pure PEG does not possess can also be imparted to PCCs by the aerogels. The PTEG assembled with PCCs and thermoelectric components can achieve a continuous output of over 1500 s after 300 s of light irradiation. After integrating the output of the device during the lamp on/off period, it is found that the total output of the device during the light-off period (8.4 V and 9.6 mW) can far exceed its total output during the light-on period (2.7 V and 4.4 mW). This work provides guidance for modulating the performance of PCCs and giving PTEGs the ability to operate under emergency or extremely harsh conditions and the prepared PTEGs are highly promising for practical use.

Flexible and Form-Stable Phase Change Composites Enabled by Pinecone-like Structure for Efficient Thermal Management

Flexible and Form-Stable Phase Change Composites Enabled by Pinecone-like Structure for Efficient Thermal Management

A novel multisource energy harvester with enhanced thermal conductivity for efficient energy harvesting and superior EMI shielding

With the rapid growth of industries, renewable energy sources like wind and solar have emerged as prominent alternatives. However, their inherent intermittency demands the development of efficient energy harvester technologies. Conventional energy harvesters are limited to capturing a single energy type, resulting in compromised storage capabilities. Moreover, the detrimental effects of electromagnetic interference (EMI) on equipment necessitate immediate attention. To address these challenges, we present the development of a novel phase change composite, CMW@PEG, which possesses remarkable enhancements in thermal conductivity (1.26 W/m∙K), electrical conductivity (71.9 S/cm), and UV absorption capacity (close to 1). Notably, this composite exhibits an outstanding EMI shielding capability of 49.36 dB, safeguarding equipment operations effectively. Furthermore, it showcases impressive solar-thermal (87.9 %) and electric-thermal (93.3 %) conversion efficiencies. The unique properties of CMW@PEG offer a pioneering strategy for harnessing and utilizing renewable energy efficiently and hold tremendous promise in advancing the sustainable energy landscape.

Carbonization welding graphene architecture for thermally conductive phase change composites with solar/electric-to-heat conversion ability

Graphene-based porous architectures are promising in addressing the poor thermal conductivity, leakage, shape stability problems of organic phase change materials (PCMs), meanwhile endowing them with excellent solar/electric-to-heat conversion ability, but they are still limited by the high interfacial thermal/electrical resistance in architectures caused by organic “binders”. In this work, in view of the excellent gel ability of aramid nanofibers (ANF) and its highly ordered conjugate molecular structure, a promising graphene porous architecture assisted by ANF was constructed by unidirectional freeze casting coupled with carbonization welding technique. Due to the similar graphite lattice structure of ANF-derived carbonization and graphene, the interfacial thermal/electrical resistance in highly vertically oriented graphene architecture was greatly reduced. As a result, the PCMs composite encapsulated by the graphene architecture carbonizing at 1500 °C exhibited an outstanding thermal conductivity of as high as 4.85 W/mK at only 4.26 vol%, which enables a rapid heat transfer and storage in PCM composite. The honeycomb porous graphene architecture with high porosity can accommodate sufficient PCMs for energy storage, showing a high latent heat enthalpy of 149.7 J/g with excellent shape stability during phase change process. More importantly, the graphene architecture endows PCM composites with excellent solar/electric-to-thermal conversion capacities, which not only expands the types of energy stored by PCMs, but is also promising in the thermal management application requiring a continuous and stable temperature environment.