Low-cost scalable high-power-density solar thermochemical energy storage via accelerating ion diffusion in Calcium-based solid wastes

Calcium-based solar thermochemical energy storage (TCES) has a great potential for next-generation concentrated solar power (CSP) systems due to its unique advantages of high operation temperature from 750 ℃ to 900 ℃ and high energy storage density, while current Calcium-based pellets suffer from poor cyclic stability and slow reaction kinetics. The mainstream solution relies on expensive inert stabilizers and complicated fabrication processes, which severely limited their affordability and scalability. Herein, we propose a strategy for recycling different Ca-based solid wastes, achieving low-cost and scalable high-power-density solar TCES simultaneously via the synergistic effect of multiple solid wastes and MgCl₂. The power density of proposed pellets is 2 times than that of the conventional CaCO₃, as the promoted solid-state diffusion of Ca²⁺ accelerates the decomposition of CaCO₃. The energy storage density is as high as 1191 kJ/kg after 50 cycles, along with energy storage economy higher than 70 MJ/$ and friction loss less than 0.3 %, far exceeding that of the state-of-the-art Calcium-based TCES pellets. The feasibility of high-performance solar-driven TCES is further demonstrated on a pilot-scale system, providing a promising high-temperature thermal energy storage solution for next-generation CSP techniques.