From Graphene Oxidation to Structural Defects: The Role of Interlayer Spacing and sp ³ Hybridization in Lithium‐Ion Battery Anodes

Carbon‐based anodes remain central to lithium‐ion battery development, yet the relationship between oxidation state, structural disorder, and lithium‐ion transport kinetics is still incompletely understood. Here, we systematically compare commercial graphite (GPH), graphene oxide (GO), and exfoliated graphene (EGPN) as anode materials, combining morphological (scanning electron microscopy [SEM]), structural (X‐ray diffraction [XRD]), and chemical (X‐ray photoelectron spectroscopy [XPS]) characterization with an evaluation of electrochemical performance. Our results reveal that oxidation degree governs a fundamental trade‐off: insufficient oxidation, as in GPH, limits interlayer spacing and constrains Li + transport, while excessive oxidation, as in GO, introduces sp 3 ‐rich domains and oxygen‐containing functional groups that impede both electronic conductivity and ionic mobility. EGPN occupies a productive middle ground; its moderate surface functionalization and expanded interlayer spacing collectively enhance solid‐state and interfacial Li + diffusivity by up to two orders of magnitude relative to GO, enabling a specific capacity of 165 mAh g −1 at 1C with lower polarization losses. These findings demonstrate that electrochemical performance in carbon anodes is not simply a function of surface area or defect density, but of achieving an optimal balance between sp 2 conductivity and controlled functionalization, a design principle with direct implications for next‐generation, high‐rate carbon anode materials.