Thermal energy storage and solar energy utilization enabled by novel composite sodium acetate trihydrate/sodium dihydrogen phosphate dihydrate phase change materials

Sodium acetate trihydrate (SAT) with a working temperature of about 58 degrees C is a significant working medium in thermal energy storage and solar energy utilization. However, supercooling effect inevitably hinders its heat release in practical applications. Typically, nucleating agents can effectively eliminate the supercooling of SAT. A concomitant problem is that the nucleating agent addition reduces the thermal energy storage capacity. In this work, a state-of-the-art methodology is constructed to eliminate the supercooling and preserve the thermal energy storage capacity of SAT synchronously by utilizing the sodium dihydrogen phosphate dihydrate (SDPD) as a novel nucleating agent. The supercooling of SAT can be reduced from 34.8 degrees C to 0 degrees C when increasing the SDPD content from 0% to 1.2%. The corresponding latent heat is slightly increased from 227.30 Jg-1 to 248.77 Jg-1. Thermal conductivity is maintained at a relatively high level of 0.6 Wm-1K-1. Polypyrrole (PPY) with strong solar absorption is assembled with the SAT/SDPD composites to realize the solar energy harvesting. Taking the advantages of the functional components, the proposed SAT/SDPD/PPY device is applied in personal thermal management and the thermoelectric power generation to produce thermal comfort and clean electric energy by the solar-thermal conversion, thermal energy storage and thermal energy utilization. This work provides a new strategy for manufacturing advanced inorganic PCMs and paves the way for the application of inorganic PCMs toward solar energy utilization.