Critical Role of Potential‐Driven Charge Effects in Hard Carbon Anodes for Sodium Storage

Abstract Sodium (Na) storage in hard carbon (HC) is a fundamental electrochemical process for sodium‐ion batteries, where adsorption energy critically influences charge/discharge rates and storage capacity. Accurate prediction of this energy is essential for designing of high‐performance HC. Traditional quantum mechanical simulations often neglect charge effects from electrochemical potentials, leading to inaccurate adsorption energies and discrepancies with experiments. Here, we demonstrate that potential‐driven charge effects play a pivotal role in governing Na storage under realistic conditions. To address this, we develop a charge‐dependent computational model (CDM) that explicitly incorporates potential‐induced charge dynamics. Using flat carbon layers as a model, we show that charge effects significantly influence the identification of active Na‐storage sites and induce sodiation/desodiation voltage shifts exceeding 1.1 V relative to conventional charge‐neutral models. These effects originate from distinct chemical reactivities between neutral and charged carbon. When extended to curved and defect‐rich carbon—hallmarks of HC—CDM accurately predicts storage sites and voltage‐capacity profiles that closely match experimental data. This work resolves long‐standing theory‐experiment inconsistencies and provides a powerful framework for designing next‐generation sodium‐ion batteries.