Lattice Compression-Driven Electron Localization and Ir-O Coupling Synergistically Enable Ultralow Overpotential Li-CO2 Batteries

Developing efficient cathode catalysts plays a crucial role in improving the CO₂ reduction reaction (CO₂RR) and CO₂ evolution reaction (CO₂ER) kinetics in Li–CO₂ batteries. However, the chemical stability of the wide-bandgap insulator Li₂CO₃ severely hinders the CO₂ER. To address this challenge, this study proposes a lattice compression strategy in which electronic localization accelerates the CO₂RR, thereby enhancing Ir–O coupling and inducing the formation of low-crystallinity Li₂CO₃, ultimately optimizing the CO₂ER process. This approach enables the Li–CO₂ 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 CO₂RR. Subsequently, the strengthened Ir–O coupling modulates the symmetry of Li₂CO₃ 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.