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CaCO3/CaO materials possess the advantages of low cost, high energy storage density, and working temperature, which offer these materials the potential to be used in thermochemical energy storage systems for concentrated solar power plants. However, CaCO3/CaO materials possess poor antisintering and optical absorption abilities, largely limiting their practicability for direct solar utilization. In this study, binary ion doping of Fe/Mn and Zr-based stabilizer incorporation were simultaneously conducted to improve the cyclic thermal energy storage/release performance of CaCO3/CaO materials. The spectral absorbance of synthetic CaO-based composites (ranging from 77.8% to 84.0%) doped with binary ions of Fe/Mn is greatly increased in comparison to that of pure CaO (∼12.2%) due to the generation of black Ca2Fe2O5 and Ca4Mn3O10. The cyclic thermal energy storage/release performances of synthetic CaO-based composites were comparatively investigated under two thermal energy storage modes (CSP-N2 and CSP-CO2). The Zr-doped, CaO-based composites exhibit a cycling stability superior to those of Zr-free CaO-based composites due to the generated inert CaZrO3 with desirable antisintering ability, and the superiority is more prominent under CSP-CO2 mode. After 50 cycles, the CaO-based composite with a molar ratio of Ca:Zr = 100:6.7 exhibits a remarkably stable energy release density of 1.02 MJ/kg under CSP-CO2 mode, retaining 88.9% of its initial energy release density.

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Calcium looping is a promising postcombustion CO 2 capture technology due to its low cost and widespread applicability. However, CaO-based sorbents are prone to encounter severe sintering and elutriation during practical carbonation/ calcination cycles. To overcome the above issues, core-in-shell CaO-based pellets composed of a highly reactive CaO-based core and a hard cement-based outer shell were prepared. The highly reactive core contains 80 wt % Ca(OH) 2 and 20 wt % cellulose, which was prepared via an extrusion−spheronization method. The cement-based outer shells were prepared via an approach of coating, and different amounts of cellulose (varying from 0 to 40 wt %) were added as a pore-forming template. It is found that the mechanical properties of the fresh, core-in-shell, cellulose-templated CaO-based pellets are gradually improved with the increased addition ratio of cellulose in the outer shell. It is mainly attributed to the adequately dispersed cellulose fibers reinforcing the cement-based outer shell. Although the high-temperature calcination causes the internal structure of the CaO-based pellets to become loose, they still exhibit relatively desirable compression strengths (0.95−1.80 MPa). Moreover, the porous outer shell contributes to promoting the accessibility of CO 2 to the highly reactive core pellet, consequently obtaining superior CO 2 capture performance. After 15 cycles, the core-in-shell, cellulose-templated CaO-based pellets containing 40 wt % of cellulose in the outer shell exhibit the highest CO 2 capture capacity of 0.144 g/g, which is nearly 6.8 times that of the core-in-shell pellets with pure cement shell.