Operando SAXS/WAXS Reveals the Formation of Li ⁺ Conduction Pathways Enabled by Apocynum Venetum‐Derived Nanocellulose

ABSTRACT Molecular engineering of cellulose is essential for improving ionic conductivity and mechanical stability in solid polymer electrolytes. This work presents the first utilization of apocynum venetum, a drought‐resistant biomass, as a sustainable source of cellulose nanofibers (CNFs) to investigate lithium‐ion (Li + ) transport mechanisms in composite polymer electrolytes for lithium metal batteries (LMBs). The reconstructed type II cellulose disrupts the polymer chain order by reorganizing hydrogen bonds and expanding amorphous regions, leading to a high Li + transference number of 0.67 and an extended electrochemical window of 5.5 V. Operando synchrotron SAXS/WAXS reveals that CNFs modulate the structural evolution of the electrolyte and facilitate the formation of continuous Li + conduction pathways within the amorphous phase. Through ion–dipole interactions among CNFs hydroxyl groups, PEO ether oxygens, and Li + , dynamic Li + ─O coordination structures are formed, enhancing Li + mobility. This work demonstrates the critical role of apocynum venetum‐derived nanocellulose in enhancing the performance of bio‐based polymer electrolytes.