This review article explores the critical role of additives in enhancing the performance and durability of thermochemical energy storage (TCES) materials, particularly in limestone-based systems. It evaluates various strategies, including hydration and the use of fine particles, along with additives like Al2O3 and ZrO2, to address challenges like performance degradation and sintering over multiple cycles. Additionally, the review examines how multicyclic stability and material activity toward CO2 are related. It emphasizes the importance of selecting support materials that optimize both stability and reactivity. Furthermore, it highlights the need for systematic investigation into the selection, synthesis methods, and additive percentages to identify optimal formulations for improved multicyclic stability. Finally, it underscores the importance of understanding the mechanisms of interaction between additives and CaO/CaCO3 matrices to guide the design of effective additive-integrated systems. This comprehensive analysis provides valuable insights into current methodologies, emerging trends, and future directions for advancing sustainable energy storage technologies.