The achievement of European climate energy objectives which are contained in the European Union's (EU) “20–20–20″ targets and in the European Commission's (EC) Energy Roadmap 2050 is possible, among other things, through the use of energy storage technologies. The use of thermal energy storage (TES) in the energy system allows to conserving energy, increase the overall efficiency of the systems by eliminating differences between supply and demand for energy. The article presents different methods of thermal energy storage including sensible heat storage, latent heat storage and thermochemical energy storage, focusing mainly on phase change materials (PCMs) as a form of suitable solution for energy utilisation to fill the gap between demand and supply to improve the energy efficiency of a system. PCMs allow the storage of latent thermal energy during phase change at almost stable temperature. The article presents a classification of PCMs according to their chemical nature as organic, inorganic and eutectic and by the phase transition with their advantages and disadvantages. In addition, different methods of improving the effectiveness of the PCM materials such as employing cascaded latent heat thermal energy storage system, encapsulation of PCMs and shape-stabilisation are presented in the paper. Furthermore, the use of PCM materials in buildings, power generation, food industry and automotive applications are presented and the modelling tools for analysing the functionality of PCMs materials are compared and classified.

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Latent thermal energy storage technologies and applications: A review

A review of melting and freezing processes of PCM/nano-PCM and their application in energy storage

Thermophysical properties and applications of nano-enhanced PCMs: An update review

Phase change materials (PCMs) have been widely used for passive thermal management and energy storage due to the high latent heat capacity near phase transition points. However, the low thermal conductivity and leakage issue are two long-standing bottlenecks in PCM-based heat-related applications. Although the state of the art can address one or both of these issues by synthesizing phase change composites (PCCs), it remains challenging to achieve high-performance PCCs with simultaneously superior thermal and mechanical properties and phase change behaviors. In this work, a new method is reported to prepare highly thermally conductive, flexible and leakage-proof PCCs by constructing dual polymer and graphite nanoplatelet networks as the functional matrix of PCMs. In the composites, paraffin wax serves as the PCM, the macromolecular olefin block copolymer (OBC) forms a cross-linked polymer network to enclose the molten PCM and endow the composite film with flexibility, and expanded graphite (EG) with a long-chain structure forms an aligned and interconnected graphite nanoplatelet percolation network to enable the high thermal conductivity of PCCs. The radial thermal conductivities reach 4.2–32.8 W m−1 K−1 at EG loadings of 5–40 wt%. The resultant flexible composite film shows efficient and reliable thermal management performance by lowering the working temperature of a commercial lithium-ion battery by more than 12 °C at high discharge rates. Our work provides an efficient and cost-effective route to synthesizing high-performance PCCs for various heat-related applications including the thermal harvesting of renewable energy, building energy management, thermal management of electronics, etc.

Highly thermally conductive and flexible phase change composites enabled by polymer/graphite nanoplatelet-based dual networks for efficient thermal management

Thermal energy harvesting technologies based on composite phase change materials (PCMs) are capable of harvesting tremendous amounts of thermal energy via isothermal phase transitions, thus showing enormous potential in the design of state-of-the-art renewable energy infrastructure. Great progress has been recently made in terms of enhancing the thermal energy storage capability, transfer rate, conversion efficiency and utilization of composite PCMs. Although there are some recent reviews on composite PCMs, they are mainly concentrated on the thermal transfer enhancement and conventional utilization of PCMs. There are few systematic reviews concerning optimization strategies of PCM for thermal energy conversion. In particular, advanced multifunctional utilization of PCMs is still in its infancy. Herein, we systematically summarize the optimization strategies and mechanisms of recently reported composite PCMs for thermal energy storage, thermal transfer, energy conversion (solar-to-thermal, electro-to-thermal and magnetic-to-thermal conversion) and advanced utilization (fluorescence emission, infrared stealth technologies, drug release systems, thermotherapy and thermal protection), including some novel supporting materials (BN nanosheets and metal organic frameworks (MOFs)). Simultaneously, we provide in-depth and constructive insights into the correlations between the structural optimization strategies and thermal performances of composite PCMs. Finally, future research trends, alternative strategies and prospects are also highlighted according to up-to-date optimization strategies.

Kuai Zihan

Papers

Thermal conductivity enhancement on phase change materials for thermal energy storage: A review

Experimental and numerical study of modified expanded graphite/hydrated salt phase change material for solar energy storage

Experimental investigation on a MnCl2–SrCl2/NH3 thermochemical resorption heat storage system

Preparation and thermal property analysis of a novel phase change heat storage material

Corrigendum to: “Thermal conductivity enhancement on phase change materials for thermal energy storage: A review”