Dynamic electrochemical coupling of sodium storage and interfacial chemistry in biomass-derived hard carbon

Hard carbon is an anode for sodium-ion batteries, but its performance is constrained by sluggish Na + transport, heterogeneous electronic polarization, electrolyte decomposition, and interfacial degradation. Herein, we develop an Adaptive Chemical Feedback Network (ACFN) that couples sodium adsorption, electronic redistribution, ion transport, and interfacial evolution within a hard-carbon framework (Adaptive HC). Adaptive HC is derived from lotus stem through tannic-acid impregnation, polydopamine coating, boron coordination, Ti 3 C 2 T x MXene assembly, and carbonization at 900 °C. Characterization reveals hierarchical porosity, N/O/B-containing environments, and an interconnected MXene-derived conductive network. Operando Raman, impedance spectroscopy, and Na 1s XPS elucidate structural and interfacial evolution, while depth-resolved XPS reveals a thinner SEI on Adaptive HC (12.8 ± 1.6 nm) than HC (24.5 ± 2.1 nm) after 100 cycles, with higher NaF contribution. DFT calculations identify strengthened Na adsorption and a reduced Na + migration barrier from 0.52 to 0.23 eV. Adaptive HC delivers 410–127 mAh g −1 at 0.05–5.0 A g −1 , 91.2% retention after 3000 cycles at 0.5 A g −1 , and 86.9% ICE at 0.20 A g −1 . A full cell delivers 222 mAh g −1 at 1.0 A g −1 . These findings establish ACFN as a strategy for durable, high-rate sodium storage.