for CO 2 sequestration and environmental remediation, the utilization of CO 2 in metal (Li)-CO 2 batteries with a high theoretical specific capacity has recently attracted considerable attention. [3,4] Apart from the CO 2 sequestration, Li-CO 2 batteries offer an advantage for energy conversion and storage, particularly for exploration of the planet Mars with an atmosphere consisting of 96% CO 2 . [3] The driving force for energy conversion and storage in Li-CO 2 batteries is the reversible redox reaction between a lithium anode and CO 2 gas cathode to form/decompose Li 2 CO 3 during the discharge/charge processes. The sluggish CO 2 reduction and evolution reactions that take place at the air cathode often impede the kinetics of Li-CO 2 batteries, leading to a high voltage (>4.5 V vs Li/Li + ) for decomposing the discharge product (Li 2 CO 3 ). [5][6][7] Under such a high anodic potential, the electrolyte oxidation limits the energy efficiency and cycling life of the Li-CO 2 batteries. [5][6][7] Therefore, efficient A highly efficient cathode catalyst for rechargeable Li-CO 2 batteries is successfully synthesized by implanting single iron atoms into 3D porous carbon architectures, consisting of interconnected N,S-codoped holey graphene (HG) sheets. The unique porous 3D hierarchical architecture of the catalyst with a large surface area and sufficient space within the interconnected HG framework can not only facilitate electron transport and CO 2 /Li + diffusion, but also allow for a high uptake of Li 2 CO 3 to ensure a high capacity. Consequently, the resultant rechargeable Li-CO 2 batteries exhibit a low potential gap of ≈1.17 V at 100 mA g −1 and can be repeatedly charged and discharged for over 200 cycles with a cut-off capacity of 1000 mAh g −1 at a high current density of 1 A g −1 . Density functional theory calculations are performed and the observed appealing catalytic performance is correlated with the hierarchical structure of the carbon catalyst. This work provides an effective approach to the development of highly efficient cathode catalysts for metal-CO 2 batteries and beyond.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.201907436.The overuse of fossil fuel has caused a rapid increase in CO 2 emissions and the associated severe environmental issues, including global warming, polar ice melting, sea level rising, rain acidification, and species extinction. [1,2] As a new strategy