An enhanced three-stage model for sodium storage in hard carbons

Abstract

characterization techniques, we propose a refined model of sodium storage in hard carbons. Our findings reveal a three-stage process: first, a fast-capacitive mechanism dominates in the slope region; second, a transition phase occurs at the early plateau, where faradaic processes become significant at the carbon micropore inner surface; and finally, micro- and slit-pore filling becomes dominant at the late plateau, driven by a multilayer-like deposition of quasimetallic sodium in the micropores. We believe this refined mechanism promotes a better understanding of the sodium storage mechanism in hard carbons and provides the basis for the rational design of carbon anode materials with superior performance for sodium-ion batteries.