The structural, electronic, and phonon properties of Li₈ZrO₆ are investigated with the application of density functional theory and lattice phonon dynamics. Based on the calculated data, the thermodynamics of CO₂ absorption–desorption for Li₈ZrO₆ is analyzed and compared with those of Li₂ZrO₃ and Li₆Zr₂O₇. The band gap of Li₈ZrO₆ is indirect along Γ–L with a value of 4.74 eV. From the calculated thermodynamic properties of Li₈ZrO₆ reacting with CO₂, we found that Li₈ZrO₆ could be regenerated at high temperatures (>1100 K). Our results indicated that the lithium zirconate with a lower Li₂O/ZrO₂ ratio has a lower turnover temperature. Hence, by mixing or doping two or more materials to form a new material, it is possible to find or synthesize CO₂ sorbents that can fit the industrial needs for optimal performance. Although the CO₂ capture capacity of Li₈ZrO₆ is much higher than that of Li₂ZrO₃, the high energy required for regeneration, the capacity loss during long absorption–desorption cycles, solid sintering at high temperature, and the material cost may affect its overall capture performance. Our results also provided some general guidelines for designing new CO₂ sorbents.