Recent advances in energy storage and applications of form-stable phase change materials with recyclable skeleton

With the expansion of the global population, the energy shortage is becoming increasingly acute. Phase change materials (PCMs) are considered green and efficient mediums for thermal energy storage, but the leakage problem caused by volume instability during phase change limits their application. Encapsulating PCMs with supporting materials can effectively avoid leakage, but most supporting materials are expensive and consume huge of natural resources. Carbon materials, which are rich and renewable resources, can be used as economical and environmentally friendly supporting skeletons to prepare form-stable PCMs. Although many researchers have begun to use recyclable materials especially various derivatives of carbon as supporting skeletons to prepare form-stable PCMs, the preparation methods, thermophysical properties and applications of form-stable PCMs with recyclable skeletons have rarely been systematically summarized yet. Form-stable PCMs with a recyclable skeleton can be used as green and efficient thermal storage materials due to their high heat storage capacity and good thermophysical stability after 2000 thermal cycles. This review investigates the effects of recyclable skeletons on the thermophysical properties including phase change temperature, latent heat, thermal conductivity, supercooling, and thermal cycling reliability. Four major kinds of recyclable skeletons are focused on: biomass, biochar, industrial by-products as well as waste incineration ash. Additionally, the application scales of form-stable PCMs with recyclable skeletons are explicated in depth. Moreover, the main challenges confronted by form-stable PCMs with recyclable skeletons are discussed, and future research trends are proposed. This article provides a systematic review of the form-stable PCMs with recyclable skeletons, giving significant guidance for further reducing carbon emissions and promoting the development of sustainable energy.