<scp>LiTFSI</scp> salt concentration effect for well‐balanced ion transport and physical properties in nanocellulose‐reinforced <scp>PEO</scp>#600 solid electrolytes

Abstract Poly(ethylene oxide) (PEO) with an oxygen group serves as a reactive site for the pathway of lithium‐ion transport. Reducing the PEO crystal domain in solid electrolytes is an extremely efficient approach for enhancing the mobility of ions. The present study applied various EO/Li molar ratios to modify the physical and electrochemical properties of PEO nanocomposite reinforced by nanocellulose. An elevated lithium salt concentration causes a gradual decline in crystallinity and mechanical strength. The electrochemical performance of the 13 EO/Li molar ratio voltammogram and charge–discharge shows efficient Li‐ion transport with 5.6 × 10 −4 S/cm conductivity at room temperature and 131 mA h g −1 initial discharge capacity. The shifting glass transition and melting point at lower temperatures (−40.5 to −44.5°C and 45.3–43.8°C) suggest greater ion mobility throughout the large non‐crystalline structure. Lithium ions are limited by membrane weakening and re‐crystallization caused by high lithium salt (EM_11) concentrations. EM_13 has the highest specific capacity, operating voltage, and lithium transfer number depends on balanced electrochemical performance and physical features. XPS surface chemistry analysis explains LiF, Li 2 CO 3 , and Li 2 O solid electrolyte interfaces (SEI) in EM samples. A lower Li 2 O (11.62 at.%) than LiF (38.4 at.%) after cycling enhances Li‐ion diffusion and cell reversibility.