Liquid Metal-Enhanced Phase-Change Composites for Efficient Solar–Thermal–Electric Energy Conversion

The accelerating depletion of fossil fuels and escalating global energy demands have driven an urgent need for sustainable and clean energy solutions. Solar-thermal-electric systems are highly promising but are inherently limited by their real-time dependence on sunlight. Phase-change materials (PCMs) provide a potential pathway for overcoming this constraint by enabling thermal storage and delayed utilization, but conventional PCMs suffer from low thermal conductivity and poor photothermal efficiency. In this work, we develop a high-performance PCM composite by constructing a hybrid thermal conduction filler network combining sodium alginate-stabilized liquid metal nanoparticles and cellulose nanofiber-modified graphene nanoplatelets. Upon vacuum-assisted paraffin impregnation, the resulting PCM composite achieves excellent photothermal conversion efficiency of 92.7%, exceptional thermal conductivity of 24.02 W m^-1 K^-1 at low filler loadings of 8.35 wt %, and high latent heat retention of 98% after 100 thermal cycles. When integrated into solar-thermal-electric systems, the fabricated PCM composite ensures not only efficient solar energy harvesting and heat generation but also gradual, stable heat release and transfer, enabling sustained power outputs up to 694.3 mV and 74.7 mA. This study provides an innovative and scalable materials design strategy for overcoming the key limitations of traditional PCMs, offering broad potential for next-generation solar energy harvesting, thermal management, and sustainable energy conversion technologies.