A team of materials scientists has developed a bio-based carbon airgel, derived from chitin, that improves thermal energy storage in shape-stabilized phase-change materials while addressing leakage during melting.
Phase change materials store and release heat as they melt and solidify, so they are used in building temperature control, solar thermal storage and electronic thermal management. Many organic phase change materials leak when they melt, which shortens their service life and limits their practical application.
In the study published in Sustainable Carbon Materials, researchers converted chitin, a natural polymer found in crustaceans and fungi, into an ultra-light airgel and then carbonized it to obtain a porous carbon framework. This chitin-derived carbon airgel encapsulates stearic acid, a widely studied organic phase change material, yielding a shape-stabilized composite that retains its solid shape even when the stearic acid phase changes to liquid.
“Our goal was to design a low-cost and environmentally friendly support that can hold large amounts of phase change material without leakage,” said corresponding author Hui Li. “Chitin is abundant, renewable and naturally rich in nitrogen, making it particularly attractive for this purpose.”
The carbon airgel exhibits an interconnected pore structure with a large pore volume that accommodates molten stearic acid. Capillary forces and hydrogen bonding between the airgel surface and the stearic acid molecules prevent the liquid from escaping, allowing the composite to contain up to sixty percent by weight of stearic acid without visible leakage.
Thermal measurements showed that the composite achieves a melting enthalpy of approximately 118 joules per gram, giving it a high thermal storage density. This value exceeds that of many previously reported phase change composites from biomass and is associated with a higher thermal conductivity than pure stearic acid, which supports faster heat absorption and release.
Durability testing showed that the material maintains stable performance with repeated use. After one hundred heating and cooling cycles, the composite maintained nearly the same phase change temperature and retained more than ninety-seven percent of its initial heat storage capacity, while structural and chemical characterization confirmed that the carbon framework remained intact.
“Long-term reliability is essential for real energy storage systems,” says Hui Li. “Our results show that this chitin-based carbon airgel can repeatedly store and release heat without structural degradation.”
The researchers reported that the carbon airgel increases the activation energy for the phase change of stearic acid, reflecting improved thermal stability. They attribute this effect to the nanoscale confinement of the phase change material within the pores and hydrogen bonding interactions with the nitrogen-doped carbon surface.
Because chitin can be recovered from seafood processing waste, the approach links waste valorization to energy storage technology. The team notes that the same strategy can be adapted to other phase change materials and tailored to different temperature windows.
“This work shows how sustainable carbon materials can address both energy efficiency and environmental concerns,” said Hui Li. “It opens up new possibilities for greener technologies for thermal energy storage in buildings, electronics and renewable energy systems.”
The study illustrates how combining natural polymers with a porous carbon design can produce practical materials for thermal energy storage while reducing dependence on fossil feedstocks.
Research report:Chitin airgel-derived carbon for shape-stabilized phase change materials with enhanced thermal energy storage
