Toward grand-canonical, potential tunable orbital-free computation of battery electrodes: An initial assessment on lithium-ion intercalated graphite

As a canonical electrode material in lithium-ion batteries (LIBs), the diffusion of lithium ions within the graphite electrode is governed by the synergistic effects of electrochemical and structural factors during the operation of LIBs. Accurately obtaining electronic structures and ion transfer processes under constant potential conditions, which represent real working conditions, is challenging in the simulation of ion intercalation into layered electrode materials in batteries. To address this, this study develops a 3D potential tunable orbital-free density functional theory (PT-OFDFT) model and realizes the simulation calculations. This model not only enables engineering calculation of lithium-ion diffusion in bilayer graphene (BLG) but also predicts lithium diffusion barrier changes under strain. Through atom, molecule, and BLG simulations, the study quantitatively analyzes the effects of electron density gradients and atomic radii, and proposes parameter selection strategies for constant potential conditions. Consequently, this offers a new 3D simulation method for ion intercalation studies, with high flexibility, low computational cost, and accurate energy and electron density modeling under constant potential. This study not only provides key theoretical tools for in-depth understanding of ion intercalation mechanisms, but also has significant guiding significance for the rational design and performance optimization of high-performance lithium-ion battery electrode materials. Applying this method is expected to drive the development of lithium-ion battery technology toward higher energy density and longer cycle life.