Review on the role of metals in the field of phase change materials: From their use for thermal energy storage to multifunctional applications

• Metallic PCMs are presented and compared to the other material classes. • Pros and contras of metallic PCMs are presented. • The role of metals as thermal conductivity enhancers is described. • Composite PCMs with metals are presented with their multifunctional purposes. The recent energy crisis has driven the research community attention toward the development of new strategies for managing available resources. Phase Change Materials (PCMs) offers the possibility of storing a large amount of thermal energy at almost constant temperature. PCMs include different classes of materials: organics, inorganics and eutectics. Among the inorganic PCMs, metallic materials—despite the high energy density and thermal conductivity—have attracted less attention, mainly due to challenges related to their management. Indeed, the issues related to their ease of reaction with the surrounding environment threaten the cyclic performance stability of its response. This review presents the distinctive features of metallic PCMs as well as the strategies developed for their effective management. In addition to these aspects, the present review work explores the role of metals in combination with other classes of PCMs for the development of Composite PCMs (C-PCMs) with enhanced properties. In particular, the review focuses on the impact of the introduction of metallic phases in C-PCMs on the heat transfer performance of other PCMs. After this focus, the literature survey concludes with the discussion of metal potential in enabling the creation of multifunctional C-PCMs, which operate on principles beyond those of conventional PCMs.