Phase Change Materials for Electro-Thermal Conversion and Storage: From Fundamental Understanding to Engineering Design

Phase change composite based on lignin carbon aerogel/nickel foam dual-network for multisource energy harvesting and superb EMI shielding

With the increasingly rapid pace of updates and iterations in electronic devices, electronic equipment/systems are becoming progressively intricate, aiming to achieve swift responsiveness through higher packaging density, which leads to electromagnetic interference and brings along with it heat accumulation, the creation of new composite phase change materials with efficient thermal management capabilities integrated with excellent electromagnetic interference shielding capabilities is imminent. In this study, nickel foam/lignin/rGO dual network scaffolds (LGN) with high electrical conductivity were prepared by vacuum-assisted adsorption, freeze-drying, and thermal annealing, and then PEG was encapsulated in LGN by vacuum impregnation to obtain shape-stabilized PEG/NiF/LN-rGO (PLGN) composite phase change material. The results demonstrate that the prepared PLGNs exhibit robust stability, exceptional thermal management capabilities, and commendable electromagnetic interference (EMI) shielding effectiveness (SE). Among these composites, PLGN-3 stands out with a notably high energy storage density, featuring a melting enthalpy of 140.95 J/g and a relative enthalpy efficiency of 98.72%. Benefiting from its outstanding electrical conductivity (1597.5 S/cm for PLGN-3) and superior light absorption, the PLGN composite phase change material also demonstrates highly effective photothermal and electrothermal conversion capabilities. In addition, the EMI shielding effectiveness reaches up to 69.9 dB at 8.2-12.4 GHz. In conclusion, the synthesized PLGN composite phase change material demonstrates considerable promise for mitigating electromagnetic interference and facilitating thermal energy management in electronic devices.

Aerogels for Phase-Change Materials in Functional and Multifunctional Composites: A Review

Phase-change materials (PCMs) have gained more attention during the last few decades. As the main function of these materials is to store and release energy in the form of latent heat during phase transitions, they perfectly fulfill the direction of modern research focused on energy-related topics. Although they have basic energy-related properties, recent research shows a need to upgrade those materials in terms of improving their common drawbacks like shape stability, leakage, and poor conductivity. The research related to PCM-based composites leads to imparting some additional functional properties such as different types of conversion abilities or extra performance such as shape memory and thermal protection. Together with a new emerging material group-aerogels (AGs), extra-light and highly porous matrices-PCMs could become functional and multifunctional materials. AG-PCM composites could be implemented in a large variety of applications in different sectors like energy, buildings, medical, defense, space technologies, and more. This study aims to help summarize current trends, methods, and works on PCM-aerogel composites in terms of developing new functional materials, especially for energy conversion purposes but also for improved conductivity, mechanical properties, and flame retardancy.

Roadmap for phase change materials in photonics and beyond

Phase Change Materials (PCMs) have demonstrated tremendous potential as a platform for achieving diverse functionalities in active and reconfigurable micro-nanophotonic devices across the electromagnetic spectrum, ranging from terahertz to visible frequencies. This comprehensive roadmap reviews the material and device aspects of PCMs, and their diverse applications in active and reconfigurable micro-nanophotonic devices across the electromagnetic spectrum. It discusses various device configurations and optimization techniques, including deep learning-based metasurface design. The integration of PCMs with Photonic Integrated Circuits and advanced electric-driven PCMs are explored. PCMs hold great promise for multifunctional device development, including applications in non-volatile memory, optical data storage, photonics, energy harvesting, biomedical technology, neuromorphic computing, thermal management, and flexible electronics.

Phase Change Thermal Storage Materials for Interdisciplinary Applications

Functional phase change materials (PCMs) capable of reversibly storing and releasing tremendous thermal energy during the isothermal phase change process have recently received tremendous attention in interdisciplinary applications. The smart integration of PCMs with functional supporting materials enables multiple cutting-edge interdisciplinary applications, including optical, electrical, magnetic, acoustic, medical, mechanical, and catalytic disciplines etc. Herein, we systematically discuss thermal storage mechanism, thermal transfer mechanism, and energy conversion mechanism, and summarize the state-of-the-art advances in interdisciplinary applications of PCMs. In particular, the applications of PCMs in acoustic, mechanical, and catalytic disciplines are still in their infancy. Simultaneously, in-depth insights into the correlations between microscopic structures and thermophysical properties of composite PCMs are revealed. Finally, current challenges and future prospects are also highlighted according to the up-to-date interdisciplinary applications of PCMs. This review aims to arouse broad research interest in the interdisciplinary community and provide constructive references for exploring next generation advanced multifunctional PCMs for interdisciplinary applications, thereby facilitating their major breakthroughs in both fundamental researches and commercial applications.

Phase Change Materials for Renewable Energy Storage at Intermediate Temperatures

Thermal energy storage technologies utilizing phase change materials (PCMs) that melt in the intermediate temperature range, between 100 and 220 °C, have the potential to mitigate the intermittency issues of wind and solar energy. This technology can take thermal or electrical energy from renewable sources and store it in the form of heat. This is of particular utility when the end use of the energy is also as heat. For this purpose, the material should have a phase change between 100 and 220 °C with a high latent heat of fusion. Although a range of PCMs are known for this temperature range, many of these materials are not practically viable for stability and safety reasons, a perspective not often clear in the primary literature. This review examines the recent development of thermal energy storage materials for application with renewables, the different material classes, their physicochemical properties, and the chemical structural origins of their advantageous thermal properties. Perspectives on further research directions needed to reach the goal of large scale, highly efficient, inexpensive, and reliable intermediate temperature thermal energy storage technologies are also presented.

Advanced perspectives on MXene composite nanomaterials: Types synthetic methods, thermal energy utilization and 3D-printed techniques

MXene, 2D material, can be synthesized as single flake with 1 nm thickness by using phase change material, polymer and graphene oxide. Meanwhile, the MXene and its composite derivative materials have been applied widely in electro-to-thermal conversion, photo-to-thermal conversion, thermal energy storage, and 3D printing ink aspects. Furthermore, the forward-looking utilization of the MXene nanomaterials in hydrogen energy storage, radio frequency field application, CO₂ capture and remediation of environmental pollution, is explored. This article reveals that the efficiencies of the photo-to-thermal and electro-to-thermal energy conversions with the MXene nanomaterials could reach about 80-90%. In parallel, it is demonstrated that the MXene printed ink has the excellent rheological property and high viscosity and stability of liquid, which contribute to arranging the multi-dimensional architectures with functional materials and controlling the flow rate of the MXene ink in the range of 0.03-0.15 mL/min for speedily printing and various printing structures.

Aerogels Meet Phase Change Materials: Fundamentals, Advances, and Beyond

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.

Filler dimensionality effect on the performance of paraffin-based phase change materials

HYPOTHESIS

Phase change materials have the potential for use in high-density thermal energy storage. However, their low thermal conductivity and the need for shape stabilization restrict their performances and implementation in various fields. The inclusion of thermally conductive nanomaterial as a single or hybrid filling is expected to form 3D network that enhances the thermal performances of phase change materials. The encapsulation of the colloidal composites in a polymer matrix stabilizes the phase change material.

EXPERIMENTS

A paraffin matrix was loaded with carbon-based fillers of various dimensionalities, namely, 1D-carbon nanotubes, 2D-graphene nanoplatelets, and 3D-graphite flakes. The thermal conductivity of the colloidal composite was measured by transient plane source and the latent heat capacity by differential scanning calorimetry techniques. Modeling the thermal conductivity by the effective medium approach predicts the experimental results.

FINDINGS

The thermal conductivity of the phase change material loaded with fillers is enhanced from 0.2 to 11 W (m K)^-1 (×55) compared with a filler-free paraffin matrix. We attribute this enhancement to the synergetic effect of the hybrid fillers (8 vol% graphite flakes and 12 vol% graphene nanoplatelets) and consequent compression (25 bar) of the colloidal composite. Moreover, the obtained phase change material is completely stable during charging and discharging cycles.

Thermal Properties of MXenes and Relevant Applications

The properties and applications of MXenes (a family of layered transition metal carbides, nitrides, and carbonitrides) have aroused enormous research interests for a decade since the successful synthesis of few-layer transition metal carbides in 2011. Though MXenes, as the building blocks, have already been applied in various fields (such as wearable electronics) owing to the distinctive optical, mechanical and electrical properties, their thermal stability and intrinsic thermal properties were less thoroughly investigated compared to other characteristics in early reports. The pioneering theoretical prediction of the thermoelectric nature of MXenes was performed in 2013 while the first experiment-based report concerning the degradation behavior of the 2D structure at elevated temperatures in a controlled atmosphere was published in 2015, followed by numerous discoveries regarding the thermal properties of MXenes. Herein, after a brief description of the synthesis, this Review summarized the latest insights into the thermal stability and thermophysical properties of MXenes, and further associated these unique properties with relevant applications by multiple examples. Finally, current hurdles and challenges in this field were provided along with some advices on potential research directions in the future.

Flexible engineering of advanced phase change materials

Liquid phase leakage, intrinsic rigidity, and easy brittle failure are the longstanding bottlenecks of phase change materials (PCMs) for thermal energy storage, which seriously hinder their widespread applications in advanced energy-efficient systems. Emerging flexible composite PCMs that are capable of enduring certain deformation and guaranteeing superior mutual contact with integrated devices are considered as a cutting-edge effective solution. Flexible PCMs-based thermal regulation technology can reallocate thermal energy and regulate the temperature within an optimal range. Currently, tireless efforts are devoted to the development of versatile flexible PCMs-based thermal regulation devices, and a big step forward has been taken. Herein, we systematically outline fabrication techniques, flexibility evaluation strategies, advanced functions and advances of flexible composite PCMs. Furthermore, existing challenges and future perspectives are provided in terms of flexible PCMs-based thermal regulation techniques. This insightful review aims to provide an in-depth understanding and constructive guidance of engineering advanced flexible multifunctional PCMs.

Dual-Encapsulated Highly Conductive and Liquid-Free Phase Change Composites Enabled by Polyurethane/Graphite Nanoplatelets Hybrid Networks for Efficient Energy Storage and Thermal Management

Phase change materials (PCMs) are regarded as promising candidates for realizing zero-energy thermal management of electronic devices owing to their high thermal storage capacity and stable working temperature. However, PCM-based thermal management always suffers from the long-standing challenges of low thermal conductivity and liquid leakage of PCMs. Herein, a dual-encapsulation strategy to fabricate highly conductive and liquid-free phase change composites (PCCs) for thermal management by constructing a polyurethane/graphite nanoplatelets hybrid networks is reported. The PCM of polyethylene glycol (PEG) is first infiltrated into the cross-linked network of polyurethane (PU) to synthesize hybridized semi-interpenetrated composites (PEG@PU), and then incorporated with reticulated graphite nanoplatelets (RGNPs) via pressure-induced assembly to fabricate highly conductive PCCs (PEG@PU-RGNPs). The hybrid networks enable the PCCs to show excellent mechanical strength, liquid-free phase change, and stable thermal property. Notably, the dual-encapsulated PCCs exhibit high thermal and electrical conductivities up to 27.0 W m^-1 K^-1 and 51.0 S cm^-1 , superior to the state-of-the-art PEG-based PCCs. Furthermore, the PCC-based energy device is demonstrated for efficient battery thermal management toward versatile demands of active preheating at a cold environment and passive cooling at a hot ambient. Overall, this work provides a promising route for fabricating highly conductive and liquid-free PCCs toward thermal management.

Recent Advances in Polymer-Containing Multifunctional Phase-Change Materials

Phase-change materials (PCMs) play a key role in thermal energy storage owing to their high-energy storage density and small temperature fluctuation during the phase-transition stage. Polymers, either as a supporting material to prevent liquid leakage during the phase-change process or used with specific target, have been widely recognized in the fabrication of PCM composites. In the meantime, due to the continued demand for variety of PCMs, a single thermal energy storage function seems to be insufficient to meet these needs. Thanks to the good compatibility with PCMs and the structural adjustable properties of polymers, they have been broadly used as the second component in the multifunctional PCMs composite. In this Review, strategies for multifunctional PCMs supported by polymers and their potential energy applications, such as thermal energy harvesting and storage, shape memory, wearable devices, self-cleaning, and other forms of applications, are summarized comprehensively. The future research directions and challenges of multifunctional PCMs with polymers are also discussed.

Large-Scale Fabrication of Form-Stable Phase Change Nanotube Composite for Photothermal/Electrothermal Energy Conversion and Storage

Photothermal/electrothermal advanced functional form-stable phase change materials (FSPCMs) can efficiently make use of solar energy and electrical energy by using supporting materials to encapsulate phase change materials. Herein, a novel low-cost integrated supporting material, denoted PDVB-12/PPy NTs, is quickly constructed via wrapping the polypyrrole (PPy) on the mesoporous polydivinylbenzene nanotubes (PDVB-12 NTs) through a fast oxidative initiation method. PDVB-12/PPy NTs exhibits good loading capacity (72.9 wt %) for industrial paraffin wax (IPW) due to the large specific surface area, and the resulting FSPCM composite (IPW@PDVB-12/PPy) exhibits a large latent heat of fusion (145.7 J/g), high thermal stability, and excellent shape stability. In addition, PPy imparts the IPW@PDVB-12/PPy composite with high electrical conductivity (55.6 S m^-1) and high photoabsorption ability (whole visible light band). The energy stored in the IPW@PDVB-12/PPy composite could be triggered and released under relatively low voltages (2.5 V) with electrothermal energy conversion efficiency (89.6%) or solar radiation (100 mW cm^-2) with photothermal energy conversion efficiency (85.2%). This study provides a low-cost and fast method for large-scale fabrication of supporting materials, which can be a good candidate in energy storage applications.

Carbon-Based Composite Phase Change Materials for Thermal Energy Storage, Transfer, and Conversion

Phase change materials (PCMs) can alleviate concerns over energy to some extent by reversibly storing a tremendous amount of renewable and sustainable thermal energy. However, the low thermal conductivity, low electrical conductivity, and weak photoabsorption of pure PCMs hinder their wider applicability and development. To overcome these deficiencies and improve the utilization efficiency of thermal energy, versatile carbon materials have been increasingly considered as supporting materials to construct shape-stabilized composite PCMs. Despite some carbon-based composite PCMs reviews regarding thermal conductivity enhancement, a comprehensive review of carbon-based composite PCMs does not exist. Herein, a systematic overview of recent carbon-based composite PCMs for thermal storage, transfer, conversion (solar-to-thermal, electro-to-thermal and magnetic-to-thermal), and advanced multifunctional applications, including novel metal organic framework (MOF)-derived carbon materials are provided. The current challenges and future opportunities are also highlighted. The authors hope this review can provide in-depth insights and serve as a useful guide for the targeted design of high-performance carbon-based composite PCMs.

Toward Tailoring Chemistry of Silica-Based Phase Change Materials for Thermal Energy Storage

Efficient thermal energy harvesting using phase change materials (PCMs) has great potential for thermal energy storage and thermal management applications. Benefiting from these merits of pore structure diversity, convenient controllability, and excellent thermophysical stability, SiO2-based composite PCMs have comparatively shown more promising prospect. In this regard, the microstructure-thermal property correlation of SiO2-based composite PCMs is still unclear despite the significant achievements in structural design. To enrich the fundamental understanding on the correlations between the microstructure and the thermal properties, we systematically summarize the state-of-the-art advances in SiO2-based composite PCMs for tuning thermal energy storage from the perspective of tailoring chemistry strategies. In this review, the tailoring chemistry influences of surface functional groups, pore sizes, dopants, single shell, and hybrid shells on the thermal properties of SiO2-based composite PCMs are systematically summarized and discussed. This review aims to provide in-depth insights into the correlation between structural designs and thermal properties, thus showing better guides on the tailor-made construction of high-performance SiO2-based composite PCMs. Finally, the current challenges and future recommendations for the tailoring chemistry are also highlighted.