Salt hydrates (MN·nHO)
*Advantages
** High volumetric latent heat storage capacity
** Availability and low cost
** Sharp melting point
** High thermal conductivity
** High heat of fusion
** Non-flammable
** Sustainability
* Disadvantages
** Difficult to prevent incongruent melting and phase separation upon cycling, which can cause a significant loss in latent heat enthalpy.
** Can be corrosive to many other materials, such as metals. This can be overcome by only using specific metal-PCM pairings or encapsulation in small quantities in non-reactive plastic.
** Change of volume is very high in some mixtures
** Super cooling can be a problem in solid–liquid transition, necessitating the use of nucleating agents which may become inoperative after repeated cycling