Flexible poly(1,3-dioxolane) ether in oriented-porous and two-stage modified nanocellulose for ionization/transport...

Quasi-solid polymeric electrolytes (QPEs) are promising for lithium metal batteries, yet their performance is often limited by low lithium-ion transference numbers and poor ion conductivity due to strong hydrogen bonding and weak salt dissociation. Here, we design a composite QPEs combining flexible poly(1,3-dioxolane) (PDOL) with a two-stage modified, oriented-porous cellulose nanofiber (CNF) scaffold. Through selective oxidation of 2,3-OH to aldehydes and 6-OH to carboxyls, the CNF framework reduces hydrogen-bonding density and introduces distinct coordination sites for Li⁺ and anions, enabling efficient ion decoupling. Directional freezing imparts a pore orientation degree of 0.83, facilitating axial Li⁺ migration. As a result, the composite electrolyte achieves an ionic conductivity of 2.76 × 10^-4 S cm^-1 and a transference number of 0.62 at room temperature, along with an electrochemical window of 5.2 V. In lithium symmetric cells, it supports a critical current density of 1.2 mA cm^-2 and can operate stably for over 1500 h at 0.5 mA cm^-2. Full LFP//Li cells deliver ≥98 % capacity retention for over 400 cycles at 1C. This work establishes a synergistic structural-chemical design strategy for high-performance, oxygen-rich QPEs, offering enhanced ionization, directional transport, and electrochemical stability for next-generation lithium batteries.