Redox‐Active Oxide/molten Salt Composites for Hybrid Thermal‐Chemical Energy Storage

Structurally stabilized composites are promising for using phase change materials in high‐temperature thermal energy storage (TES). However, conventional skeleton materials, which typically comprise 30–50 wt% of the composite, mainly provide sensible heat storage and contribute minimally to overall energy density. This study introduces a new class of redox‐active oxide‐molten salt (ROMS) composites that overcome this limitation by combining sensible, latent, and thermochemical heat storage in a single particle. Specifically, porous, redox‐active Ca 2 AlMnO 5+δ (CAM) complex oxide particles were demonstrated as a suitable support matrix, with the pores filled by eutectic NaCl/CaCl 2 salt. X‐ray diffraction confirms excellent phase compatibility between CAM and the salt. Scanning electron microscopy/energy dispersive X‐ray spectroscopy and nano X‐ray tomography show good salt infiltration and wettability within the CAM pores. Thermogravimetric analysis reveals that a 60 wt% CAM/40 wt% salt composite achieves an energy density of 267 kJ kg −1 over a narrow 150 °C window, with ≈50 kJ kg −1 from thermochemical storage. Additionally, the composite shows higher thermal conductivity than salt alone, enabling faster energy storage and release. ROMS composites thus represent a novel and efficient solution for high‐performance TES.