High energy storage density titanium nitride-pentaerythritol solid–solid composite phase change materials for light-thermal-electric conversion

Abstract: To achieve the goal of carbon neutrality, efficient use of solar energy is feasible and imminent. The selection of phase change materials (PCMs) as energy storage media is an effective way to achieve practical utilization to solve the uncontinuity and unstability of solar energy. Solid-solid PCMs (SS-PCMs) have attracted attention due to their advantages of stable shape, no phase separation, and no corrosion. In this paper, cheap raw material pentaerythritol (PE) is selected as the energy storage medium. Titanium nitride (TiN) with localized surface plasmon resonance is used as light absorber and thermal conductive filler. The results show that phase transition enthalpy of 0.2 wt% TiN-composite phase change materials (CPCMs) is still as high as 287.8 J/g, which maintains 96.06 % energy storage density of PE. In addition, thermal conductivity of 0.2 wt% TiN-CPCMs is increased by 109.48 %, and photo-thermal conversion efficiency is as high as 90.66 %. Simultaneously, a thermoelectric harvester integrating thermoelectric generator (TEG) with SS-PCMs is proposed. The average maximum power of the TiN-CPCMs-TEG system is 59.26 % higher than that of the PE-TEG system. Total energy of system is also increased by 58.99 %, which lays the foundation for the application of mid-temperature heat collection engineering.

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