Oriented High Thermal Conductivity Solid–Solid Phase Change Materials for Mid-Temperature Solar-Thermal Energy Storage

Abstract

As the global energy crisis intensifies, the development of solar energy has become a vital area of focus for many nations. The utilization of phase change materials (PCMs) for photothermal energy storage in the medium temperature range holds great potential for various applications, but their conventional forms face several challenges. For instance, the longitudinal thermal conductivity of photothermal PCMs is inadequate for effective heat storage on the photothermal conversion surface, and there is a risk of leakage due to repeated solid–liquid phase transitions. Here, we report a solid–solid phase change material, tris(hydroxymethyl)aminomethane (TRIS), which has a phase change temperature of 132 °C in the medium temperature range, enabling high-grade and stable solar energy storage. To overcome the low thermal conductivity problem, we propose a large-scale production of oriented high thermal conductivity composites by compressing a mixture of TRIS and expanded graphite (EG) using the pressure induction method to create in-plane highly thermally conductive channels. Remarkably, the resulting phase change composites (PCCs) exhibit a directional thermal conductivity of 21.3 W/(m·K). Furthermore, the high phase change temperature (132 °C) and large phase change entropy (213.47 J/g) enable a large-capacity high-grade thermal energy to be used. The developed PCCs, when combined with selected photo-absorbers, exhibit efficient integration of solar-thermal conversion and storage. Additionally, we also demonstrated a solar-thermoelectric generator device with an energy output of 93.1 W/m2, which is close to the power of photovoltaic systems. Overall, this work provides a technological route to the large-scale fabrication of mid-temperature solar energy storage materials with high thermal conductivity, high phase change enthalpy, and no risk of leakage, and also offers a potential alternative to photovoltaic technology.

Low dielectric constant and highly intrinsic thermal conductivity fluorine‐containing epoxy resins with ordered liquid crystal structures

“…This is because the molecular thermal motion in epoxy resins gradually increases with the increasing temperature, which is conducive to enhancing the heat transfer efficiency. On the other hand, when the external ambient temperature further increases, the internal polymer segments begin to move to weaken the order of the curing networks, increasing the phonon scattering 60 . Overall, the λ values of the above cured resins vary little with the changing temperature, showing excellent temperature stability.…”

Preparation and Properties of Acrylic Acid-Modified Multicross-Linked Two-Component Waterborne Phase-Change Polyurethane

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Expanded Vermiculite/D-Mannitol as Shape-Stable Phase Change Material for Medium Temperature Heat Storage

“…In facing the increasing unsustainable fossil fuel consumption and the large amounts of GHG emission, it is crucial to develop renewable energy systems for carbon peaking and carbon neutrality goals [ 1 ]. However, the rapid growth of the solar energy and wind energy industries has long been hindered by the inherent challenge of fluctuating energy supplies [ 2 , 3 ].…”