Lattice Compression‐Driven Electron Localization and Ir‐O Coupling Synergistically Enable Ultralow Overpotential Li‐CO 2 Batteries

Abstract Developing efficient cathode catalysts plays a crucial role in improving the CO 2 reduction reaction (CO 2 RR) and CO 2 evolution reaction (CO 2 ER) kinetics in Li–CO 2 batteries. However, the chemical stability of the wide‐bandgap insulator Li 2 CO 3 severely hinders the CO 2 ER. To address this challenge, this study proposes a lattice compression strategy in which electronic localization accelerates the CO 2 RR, thereby enhancing Ir–O coupling and inducing the formation of low‐crystallinity Li 2 CO 3 , ultimately optimizing the CO 2 ER process. This approach enables the Li–CO 2 battery to achieve an ultralow overpotential of 0.33 V and an exceptionally high energy efficiency of ∼88.7%. Moreover, even after over 1100 h of operation, the battery maintains a stable charging potential of 3.3 V, representing the best performance reported to date. Through in situ and ex situ characterizations combined with theoretical calculations, we reveal that lattice compression leads to changes in the coordination environment, thereby enhancing electronic localization effects. This accelerates Li + migration near the catalyst surface, facilitating its rapid participation in CO 2 RR. Subsequently, the strengthened Ir–O coupling modulates the symmetry of Li 2 CO 3 molecules, reduces their crystallinity, and ultimately promotes their efficient decomposition. This study provides new insights into the design of high‐performance bidirectional cathode catalysts through crystal facet engineering.