Phase-change material
A phase-change material (PCM) is a substance which releases/absorbs sufficient energy at phase transition to provide useful heat or cooling.
Water/ice is therefore a very useful phase change material and has been used to store winter cold to cool buildings in summer since at least the time of the Achaemenid Empire.
By melting and solidifying at the phase-change temperature (PCT), a PCM is capable of storing and releasing large amounts of energy compared to sensible heat storage.
PCMs are used in many different commercial applications where energy storage and/or stable temperatures are required, including, among others, heating pads, cooling for telephone switching boxes, and clothing.
These materials change their crystalline structure from one lattice configuration to another at a fixed and well-defined temperature, and the transformation can involve latent heats comparable to the most effective solid/liquid PCMs.
[15][16] Therefore, these materials have emerged as promising alternatives to traditional solid/liquid PCMs due to their ability to undergo phase transitions without liquefaction.
In addition, SSPCMs have been explored for use in smart textiles, electronics cooling systems, and thermally adaptive building materials.
Research efforts continue to optimize their thermal storage density and improve long-term cycling stability, supporting broader commercial applications.
In particular, integrating SSPCMs with nanostructured material and composite frameworks is being investigated to enhance their thermal conductivity and phase transition kinetics.
To address this problem, high thermal conductivity additives such as carbon nanotube, graphene, and metallic nanoparticles have been introduced to enhance their performance.
Additionally, volume expansion during phase transitions can impact material stability, necessitating advanced structural designs and containment strategies.
Recent studies have also explored nano-enhanced PCMs and composite structures to further optimize thermal response times and cycling stability.
Common packaging materials showing chemical compatibility with room temperature PCMs include stainless steel, polypropylene, and polyolefin.
Such hybrid materials are created to achieve specific overall or bulk properties (an example being the encapsulation of paraffin into distinct silicon dioxide nanospheres for increased surface area-to-volume ratio and, thus, higher heat transfer speeds [28]).
They have wide applications in various industries, owing to their high thermal conductivity, photo-thermal conversion efficiency, latent heat storage capacity, physicochemical stability, and energy saving effect.
This is achieved using materials like carbon-based nanostructures (e.g., graphene, CNTs), plasmonic nanoparticles (e.g., Au, Ag), and semiconductors (e.g., TiO₂, MoS₂).
High-performance PCM development Recent research has focused on enhancing the efficiency and stability of PCMs through material innovations.
New organic-inorganic composite PCMs, such as paraffin-based microencapsulated systems and salt hydrates with enhanced thermal conductivity, have demonstrated improved energy storage capabilities.
[34] In addition, metal-organic frameworks(MOFs) has investigated as a potential PCM candidates due to their tunable phase transition properties and high thermal storage density.
One promising approach is the integrations of PCMs into thermal energy storage units for solar and wind power systems.
[37][38][39] Additionally PCM-enhanced smart windows and walls have been developed to regulate indoor temperatures and reduce building energy consumption by up to 30%.
[42] Looking forward, advancements in nano-enhanced PCMs and hybrid materials are expected to further expand their applications, making them integral to future energy-efficient technologies.
Because of the increased fire risk, flamespread, smoke, potential for explosion when held in containers, and liability, it may be wise not to use flammable PCMs within residential or other regularly occupied buildings.
