The consumption of fossil fuels has led to a series of environmental issues due to CO₂ emissions, drawing increasing attention to carbon capture and storage (CCS) technology. Lithium silicate (Li₄SiO₄) is considered a highly promising sorbents due to its high CO₂ capture capacity, low regeneration temperature, and good thermal stability. However, its widespread application is limited by the high cost of silicon sources and insufficient cycling performance. Low?cost fly ash was used as silicon source to synthesize Li₄SiO₄ via solid?state and impregnation?precipitation methods, followed by modification with K₂CO₃ doping. The materials were characterized by testing methods such as XRF, XRD, and SEM.The results show that the sorbents prepared by the solid?phase method at 700 °C (LS?700) possesses a rich pore structure and a high specific surface area of 1.584 2 m2/g, and exhibits the optimal sorption performance, with the CO? sorption capacity remaining at 0.179 7 g/g after 10 cycles. After K₂CO₃ doping, the CO₂ sorption rate increased to 0.054 5 g/(g·min), which is 1.4 times that of the undoped sample. Mechanistic studies revealed that the formation of a low?temperature eutectic layer between K₂CO₃ and Li₂CO₃ promoted CO₂ diffusion and reduced the reaction activation energy. This study provides an effective strategy for developing low?cost and high?performance Li₄SiO₄?based sorbents, demonstrating significant value for enhancing CO₂ capture efficiency from coal?fired flue gas.