Long-stable solar energy capture and storage via negative thermal expansion regulated calcium-based particles

The 3rd concentrated solar power technology is considered a potential strategy to solve the energy shortage and achieve carbon neutrality in which the development of long-stable energy storage materials is the key to overcoming the intermittency and instability of solar power. Therefore, we present a calcium-based particle with a thermal expansion compensation strategy that enables high energy densities and long storage times. High measured energy densities of up to 1554 kJ kg⁻¹, long storage lifetimes of up to 260 cycles, and high spectral absorption of up to 90.8% are demonstrated in negative thermal expansion NdMnO₃/inert Al-Fe alkali metal element couples incorporated into calcium oxide structures. A set of evaluation indexes to quantitatively evaluate long-cycle heat storage performance is proposed. Based on the phenomenon that the thermal contraction of the NdMnO₃ lattice distortion counteracts the acidification volume expansion of calcium oxide, the thermal expansion compensation effect is proposed for the first time. This effect excellently ameliorates the problem of sintering and agglomeration and improves the recycling rate of calcium oxide from the perspective of microscopic thermal regulation. A new conceptual scheme is provided on long-storage-life solar thermochemical energy storage and continuous CO₂ capture technology.