Hexagonal Boron Nitride‐Modified Solar Salt Nanofluids for Thermal Energy Storage Applications

Concentrating solar power (CSP) needs efficient thermal storage, but standard molten “solar salt” is limited by modest heat capacity and high‐temperature stability. We assess hexagonal boron nitride (h‐BN) nanosheets as additives to enhance solar salt. Nanofluids with 0.5–3 wt.% h‐BN are prepared via scalable dry mixing. Thermogravimetric analysis and differential scanning calorimetry quantify decomposition temperature, melting, and heat capacity; XRD, SEM, and Raman probe structure and morphology before and after heating. Low loadings (0.5%–1%) give the best results: heat capacity increases by ∼15% ± 3% and decomposition temperature by ∼5% versus neat salt, while chemical and phase stability are maintained. At higher loadings (2%–3%), h‐BN agglomeration reduces benefits and degrades morphology. These trends are consistent with—though not proof of—interfacial nanolayers and ionic structuring at well‐dispersed 2D surfaces that redistribute heat. Scope is intentionally limited: thermal conductivity, viscosity, and multicycle durability were not measured and remain for future work. Overall, we outline a processing–structure–property window that maximizes heat capacity at low additive levels, positioning h‐BN as a stable, inert, and scalable additive for next‐generation CSP storage.