Bean‐Pod‐Inspired 3D‐Printed Phase Change Microlattices for Solar‐Thermal Energy Harvesting and Storage

Abstract

Effective and reliable encapsulation of phase change materials (PCMs) is essential and critical to the high‐performance solar‐thermal energy harvesting and storage. However, challenges remain pertaining to manufacturing scalability, high efficiency in energy storage/release, and anti‐leakage of melted PCMs. Herein, inspired by natural legume, a facile and scalable extrusion‐based core‐sheath 3D printing strategy is demonstrated for directly constructing bean‐pod‐structured octadecane (OD)/graphene (BOG) phase change microlattices, with regular porous configuration as well as individual and effective encapsulation of OD “beans” into highly interconnected graphene network wrapping layer built by closely stacked and aligned graphene sheets. The unique architectural features enable the ready spreading of light into the interior of phase change microlattice, a high transversal thermal conductivity of 1.67 W m−1 K−1, and rapid solar‐thermal energy harvesting and transfer, thereby delivering a high solar‐thermal energy storage efficiency, and a large phase change enthalpy of 190 J g−1 with 99.1% retention after 200 cycles. Most importantly, such encapsulated PCMs feature an exceptional thermal reliability and stability, with no leakage and shape variation even at 1000 thermal cycles and partial damage of BOG. This work validates the feasibility of scalably printing practical encapsulated PCMs, which may revolutionize the fabrication of composite PCMs for solar‐thermal energy storage devices.

3D-Printed Flexible Phase-Change Nonwoven Fabrics toward Multifunctional Clothing

“…Recent years have seen tremendous efforts in fabricating wearable phase-change fabrics, in which the frequently used PCMs include two distinct categories of solid–liquid and solid–solid in terms of the phase-change process. Via impregnating PCM under vacuum into a matrix with open and hierarchical pores, a variety of solid–liquid PCMs has been extensively explored for phase-change fabrics. − However, the impregnation process is time-consuming and prone to cause inhomogeneous distribution of PCMs, especially high risks of liquid leakage during multiple endothermal and exothermal processes is a long-standing bottleneck for their broad-scale practical applications. , Alternatively, solid–solid phase-change fabrics as a promising candidate, constructed with various flexible polymers including the olefin block copolymer, poly­(vinyl chloride), poly­(methyl methacrylate), thermoplastic polyurethane (TPU), − and polyethylene, − are triggering a boom in wearable fields owing to their excellent maintenance of the solid state and no substantial leakage during phase transitions. Nevertheless, the as-fabricated phase-change fabrics still suffer from a complicated manufacturing procedure and poor shape stability during the phase-change process.…”

A hierarchical thermal interface material based on a double self-assembly technique enables efficient output power via solar thermoelectric conversion

“…A concentrating technique using an optical system was developed recently to focus on thermal energy into the localized region, which is beneficial to maximize the captured solar energy. 25–27 However, since the heat conduction in traditional TIMs is either randomly distributed or unidirectional, 28,29 realizing the rapid and multidirectional thermal conductive property within TIMs for efficient thermal charging and TE discharging remains challenging.…”

D-Mannitol/Graphene Phase-Change Composites with Structured Conformation and Thermal Pathways Allow Durable Solar–Thermal–Electric Conversion and Electricity Output

“…For example, recently, Philip and his group found that the thermal conductivity and light absorption of PCMs can be significantly improved by adding cheap carbon blacks . At a high filler content or employing some judicious structural engineering methods, the thermal charging rate of the PCM could be further ameliorated, reflected by its significantly improved thermal conductivity. − However, merely high thermal conductivity cannot guarantee the adequate storage of thermal energy in the PCM. − The thermal management efficiency of PCMs needs to be designed to be conformable to their practical applications. For example, when strong sunlight is focused onto a localized region at the top surface of the PCM, heat conduction within the PCM requires exquisite manipulation according to the heat-conduction characteristic within the STEG.…”