Work

Universal Single Atom Engineering Enhances Coulombic Efficiency of Ion Storage in Carbon Materials

Year: 2025

Type: article

Abstract: Metal single atoms are widely used to optimize the microstructure of carbon materials to improve their ion storage capacity and rate performance, but the impact on another key parameter, Coulombic efficiency (CE), is not sufficiently addressed and confirmed. Herein, a universal phenomenon is reported that carbon‐loaded asymmetric sulfur‐modified metal‐N 4 moiety (MN 4 ‐S, M = Zn, Fe, Cu, and Ni) possesses higher CE than the symmetric MN 4 moiety, and this phenomenon is applicable to various of carbon matrices, ions (Li + , Na + , and K + ), charge and discharge rates, and electrolyte formulations. The carbon‐loaded asymmetric MN 4 ‐S moiety exhibits larger CEs (0.03–0.46% higher of average CEs, 4.2–28.4% higher of the initial CEs) and smaller variance compared to the MN 4 moiety, implying better reversible stability. The mechanism driving this phenomenon is revealed by the ZnN 4 ‐S sodium storage process. The asymmetric MN 4 ‐S coordination promotes the rapid ions diffusion kinetics by changing the charge density. Meanwhile, the MN 4 ‐S moiety can reduce the adsorption energy of ions and regulate the surface chemical reactivity of the material to increase the reversibility of surface ion storage, thereby achieving higher CE and better stability.

Source: Small

DOI: 10.1002/smll.202500909