Thermochemical heat storage (TCHS) is a technology that stores thermal energy through reversible chemical reactions, providing high energy density and long-term storage with minimal losses. This review highlights recent advancements in the use of salt hydrates and porous matrix composites as sorbents in TCHS systems, with a focus on their synergistic effects. It begins with an overview of heat storage systems and adsorption concepts. This discussion then addresses key challenges related to salt-hydrated and composite adsorbent materials. In practical applications, salt hydrates for thermochemical heat storage face issues such as deliquescence, agglomeration, poor kinetics, and low thermal conductivity. Consequently, this review systematically categorizes hygroscopic salts embedded in porous host matrices, including zeolite-based materials, silica gel, carbon-based composites, minerals, metal–organic frameworks (MOFs), and mixed-salt composites. These findings highlight that high-conductivity carbon-based materials are utilized to enhance heat transfer, and that MOFs and zeolite 13X can improve sorption performance. Composite materials are analyzed to prevent agglomeration, enhance cyclic efficiency, and increase energy density. Additionally, binary salts confined within porous matrices exhibit notable synergistic effects on overall performance. Finally, the review discusses current limitations and suggests future research directions for developing suitable material–adsorbate pairs.

Polytetrafluoroethylene (PTFE) blended with polyimide (PI) and filled with boron nitride (BN) is prepared through cold pressing and sintering for composites with remarkable wear resistance and reduced coefficient of friction (COF). The characterizations show that BN and PI at different levels, improve the hardness, dynamic thermo-mechanical modulus, thermal conductivity, and tribological properties of PTFE. PI boosts the dispersion and bonding of BN in PTFE. In dry sliding friction of a block-on-ring tribometer, the wear rate and COF of 10:10:80 BN/PI/PTFE reduce to almost 1/300 and 80% of those of pure PTFE, respectively, as the wear mechanism transition from being adhesive to partially abrasive. This occurs only when the additives BN and PI induce a synergistic effect, that is, at concentrations that are not higher than ca. 10 wt% and 15 wt%, respectively. The obvious agglomeration at high percentages of added PI and severe conditions (400 N and 400 rpm) induce strong adhesive failure. The variations in the tensile properties, hardness, crystallization, and microstructure of the composites correspond to different effects. The multiple parameters of the plots of wear and friction are transformed into their contour curves. The mechanism transition maps aid in understanding the influence of various test conditions and composite compositions on the contact surfaces in the space-time framework of wear.