Boron Nitride-Doped Inorganic Hydrated Salt Gels Demonstrating Superior Thermal Energy Storage and Wearability Toward High-Performance Personal Thermal Management

Abstract

Realizing the person thermal management (PTM) toward human body and its local environment is emerging as a research hotspot. Sodium sulfate decahydrate (SSD) possessing reversible thermal energy absorption, storage, and release around the human body temperature provides a promising solution for PTM and thermal comfort. However, developing SSD-based functional materials with superior thermophysical properties and wearability to enable efficient PTM still remains a huge challenge. Herein, a strategy of ionic cross-linking, chemical cross-linking, and boron nitride (BN) doping is developed to manufacture the high-performance hybrid SSD gels. The supercooling degree of the BN@SSD gels can be reduced to 0 °C. The thermal conductivity (1.2668 W m–1 K–1) of the BN@SSD gels can be increased by 63.14%. The BN@SSD gels present a large thermal energy storage capacity of 132.52 J g–1. The BN@SSD gels demonstrate excellent form stability to confine the liquid SSD and high cyclic stability of 200 cycles. Furthermore, The BN@SSD gels also possess superior wearability in terms of high flexibility, high self-repairing efficiency, and high cost effectiveness (5.53 × 10–3 ¥ g–1). Owing to the various merits of the synergistic enhancement effect, the BN@SSD gels are effectively utilized in wearable PTM to generate thermal comfort for the human body. The multifunctional thermal energy storage gels offer a promising route to the highly efficient application of PCMs in next-generation PTM.

Hybrid Polymer Salogels for Reversible Entrapment of Salt-Hydrate-Based Thermal Energy Storage Materials

“… − In contrast, covalently crosslinked polymer gels, which also often require large polymer amounts (5%–60% by weight), provide shape stabilization (Figure S1). − However, the permanent nature of the crosslinks renders these materials irreversible, making filling and removal from thermal energy storage modules impossible. In contrast to these previous strategies, our group introduced temperature-responsive polymer salogels (polymer gels in inorganic salt hydrates) based on hydrogen bonding polymers such as poly­(vinyl alcohol) (PVA), for reversible shape stabilization of liquid salt hydrates. , The on-demand reversibility of gelation by heating above a gel-to-sol transition temperature ( T gel ) allows filling and removal of the salogels from thermal energy storage devices, whereas gelation below T gel provides shape stabilization above the melting temperature of the salt hydrate ( T m ).…”