Reduced graphene oxide-modified hydrated salt phase-change microcapsules with enhanced thermal conductivity and decreased supercooling

To enhance the thermal conductivity and decrease the supercooling of hydrated salt phase-change microcapsules, reduced graphene oxide (rGO) was introduced into the sodium acetate trihydrate (SAT) microcapsules, by means of the classic water-in-oil inverse interfacial polymerization. The SAT composite @ polyurethane (PU)/rGO phase-change microcapsules with 0.15 wt% rGO demonstrated the high thermal storage density (230.7 J/g) with the phase-change enthalpy efficiency being 99.9%, ultra-low supercooling degree (1.7 °C), high thermal conductivity (0.743 W/(m·K)), strong thermal stability and thermal cycling stability (after 200 thermal cycles, the residual enthalpy ratio remains higher than 95.8%), compared to other microcapsules. When the microcapsules were used in the simulated chip thermal management system, the microcapsules not only extended the time for the temperature rise from 25 °C to 70 °C by 520.1%, but also increased the time for the temperature dropping to 25 °C by 240.6%, compared to the control situation, which displayed their extraordinary thermal buffering ability, beneficial for maintaining the working ability of the chip. This work has successfully provided a new preparation strategy for SAT phase-change microcapsules with excellent comprehensive performance.