Multiscale Defective Interfaces for Realizing Na‐CO2 Batteries With Ultralong Lifespan

Abstract Despite their favorable high energy density and potential for CO 2 recycling, Na‐CO 2 batteries have been held back by limitations in cycling capability, stemming from the sluggish CO 2 reduction/evolution reaction (CO 2 RR/CO 2 ER) kinetics at CO 2 cathode and unmanageable deposition/stripping of metallic Na at the anode upon cycling. Herein, a “two‐in‐one” electrode with multiscale defective FeCu interfaces (CP@FeCu) is presented, which is capable of improving the CO 2 RR/CO 2 ER kinetics of CO 2 ‐breathing cathode, while modulating sodium deposition behavior. Experimental and theoretical investigations reveal multiscale defective FeCu interfaces are responsible for the enhancement of sodiophilicity and catalytic properties. The defect and valence oscillation effects originate in multiscale defective FeCu interfaces, effectively facilitating the adsorption of reactants and decomposition of Na 2 CO 3 during CO 2 RR/CO 2 ER processes, along with exceptional cycling stability of 2400 cycles (4800 h) at 5 µA cm −2 . Meanwhile, the CP@FeCu with sodium affinity creates a uniform electric field and robust adsorption for Na, making initial nucleation sites more conducive to Na deposition and achieving dendrite‐resistant and durable anodes. This work offers a scientific insight into the functionalization design of “two‐in‐one” electrodes, which is essential for a unified solution to the challenges in sodium anodes and CO 2 cathodes.