Hydrocolloids: Nova materials assisting encapsulation of volatile phase change materials for cryogenic energy transport and storage

Abstract

A series of norm-defying hydrocolloid emulsifiers is reported for the challenging task of outstanding long-term retention of volatile cryogenic phase change materials (cryoPCM) in high-payload capsules. Their identification lifted previously imposed restrictions on emulsifier selection in order to fine-tune the mechanical and barrier properties, shell thickness, size and surface roughness of capsules. The exceptionally large payload in terms of both volume (~97 vol%) and weight (~95 wt%), superb long-term retention capability tested at ambient conditions up to 30 days, as well as the surprising cryo-temperature survival of synthesized capsules promote them as immensely efficient candidate carriers for cryogenic thermal energy storage and transport. Utilization of appropriate hydrocolloids and concentrations not only bestows the thermosetting polymeric shells with flexibility, but also eliminates the majority of imbedding satellite particles producing exterior surfaces comparable to a two-step synthesis route ever reported. Promising fatigue resistance within an extreme dynamic temperature range between 20 °C and −140 °C during preliminary cycling tests has been demonstrated via direct observation of capsule buckling and restoration. Such findings provide fundamental insights into achieving superior capsule quality and their far-reaching impacts beyond cryogenic energy storage on applications such as less harsh cold chain logistics, electrophoresis displays, battery safety management and self-healing materials.