Dual-beam facilitated oxygen manipulation in hard carbon for improved sodium storage

Hard carbons (HCs) are commercial anode materials for sodium-ion batteries (SIBs), yet their electrochemical performance remains limited by intrinsic structural deficiencies and insufficient Na⁺ storage kinetics. Herein, we report oxygen manipulation in hard carbon, enabled by plasma and laser beam, for improved Na⁺ storage. Starting with commercial HC electrodes, oxygen atoms are first implanted into carbon layers via atmospheric plasma treatment under controlled oxygen partial pressure. Subsequent laser irradiation induces localized thermal shocks that selectively remove oxygen atoms from edge sites, triggering transient carbon lattice rearrangement to simultaneously generate intrinsic defects and optimally sized closed nanopores (1.2-2.0 nm). This dual-stage regulation yields HC anodes with exceptional Na⁺ storage properties, achieving a high reversible capacity of 335 mAh g⁻¹ at 30 mA g^-1 (with 36% enhancement compared with pristine HC) and enhanced Na⁺ diffusion. Through in situ Raman and correlated ex situ spectroscopy analyses (EPR and XPS), we systematically decode the multiscale Na⁺ storage mechanism involving defect adsorption, interlayer intercalation and nanopore filling. The proposed methodology bridges atomic-scale structural engineering with macroscopic electrode performance optimization, offering a scalable green manufacturing pathway for next-generation SIBs.