Contents lists available at ScienceDirect Nano Energy journal homepage: www.elsevier.com/locate/nanoen Review Nanoconfinement effects on thermal properties of nanoporous shape- stabilized composite PCMs: A review Hongyi Gao, Jingjing Wang, Xiao Chen, Ge Wang ⁎ , Xiubing Huang, Ang Li, Wenjun Dong ⁎ Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory of Function Materials for Molecule & Structure Construction, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China ARTICLE INFO Keywords: Shape-stabilized composite PCMs Nanoconfinement effects Crystallization behaviors Thermal properties ABSTRACT Using phase change materials (PCMs) for thermal energy storage is an effective technique of energy management to address the mismatch problems between energy supply and demand. Shape-stabilized composite PCMs could efficiently solve their leakage problem during the solid-liquid phase change process, which have been widely used and extensively reviewed in literature. However, those reviews mainly focused on microencapsulated PCMs and the broad properties and applications of composite PCMs but paid little attention to the nanoporous shape- stabilized composite PCMs. The nanoporous shape-stabilized composite PCMs do solve the leakage problem and show excellent chemical stability and thermal cycling stability, but most of their enthalpy values were much lower than that of the pure PCMs component. So in this review we have highlighted recent progress in the research of nanoporous shape-stabilized PCMs, such as the design concept of porous support, fabrication and characterization techniques, and especially the nanoconfinement effects of the porous support on the thermal properties of the PCMs confined in the nanopores. Finally, we have provided a brief outlook of the future challenges and potential prospects of nanoporous shape-stabilized composite PCMs. This review paper will help to explore and develop better nanoporous shape-stabilized composite PCMs for practical applications and offer basic understanding of nanoconfinement effects on thermal properties. 1. Introduction Energy shortages and environmental pollution problems have be- come increasingly prominent in current society. Along with the devel- opment of advanced science and technology, non-renewable energy sources are being replaced by green and regeneration energy, such as biological energy [1], solar energy [2–5], wind energy [6–8], terrestrial heat energy [9] and ocean energy [10]. The exploit and utilization of these new energy resources have also received worldwide attention. However, the application of these energy is often and easily influenced by the weather, location and time. These energy sources possess their own disadvantages of intermittency, randomness and volatility, creating a mismatch between supply and demand in respects of time, space and intensity and resulting in low efficiency of energy utilization in the current industry field [11]. The question of how to realize the efficient use of these energy sources has become an important issue in promoting their large scale applications. Energy storage technology is one of the most efficient ways to solve above problem, which can store the discrete and random energy into the proper medium and release it again when the energy is needed [12]. Current energy storage methods mainly include sensible heat sto- rage, latent heat storage and chemical reaction heat storage [13]. La- tent heat storage is the most efficient and useful method due to its advantages of high heat storage density, little temperature fluctuation and easily controllable utility system [14–21]. In principle, latent heat storage uses the PCMs to absorb and release large amounts of latent heat during their phase change process. Thermal energy storage PCMs includes solid-solid, solid-liquid and solid-gas PCMs, among which the solid-liquid PCMs are the most practical due to their high latent heat density and small volume change [22,23]. Solid-liquid PCMs changes its phase from solid to liquid during the melting process and absorbs heat from the environment, and changes its phase from liquid to solid during the solidification process and releases heat into the environ- ment. The main problem which limits the application of the solid-liquid PCMs is the issue of leakage during the phase change process, so it must be stabilized before utilization [24,25]. Considerable efforts have been devoted to overcome these technical issues by fabrication of shape- stabilized PCMs, which mainly includes coating PCMs into a micro- capsule or adsorbing the PCMs into a porous support. Shape-stabilized composite PCMs has been widely used and https://doi.org/10.1016/j.nanoen.2018.09.007 Received 9 June 2018; Received in revised form 24 August 2018; Accepted 2 September 2018 ⁎ Corresponding authors. E-mail addresses: gewang@mater.ustb.edu.cn (G. Wang), wdong@ustb.edu.cn (W. Dong). Nano Energy 53 (2018) 769–797 Available online 13 September 2018 2211-2855/ © 2018 Published by Elsevier Ltd. T