Attapulgite-Reinforced Bacterial Cellulose Composite Separator for Dendrite-Free Sodium-Sulfurized Polyacrylonitrile Batteries

Abstract Room-temperature sodium-sulfur batteries (RT Na-S) have attracted considerable attention owing to their high energy density and the natural abundance of sodium and sulfur resources. However, conventional glass fiber separators suffer from large pore sizes and disordered ion-transport pathways, which induce nonuniform Na+ flux and accelerate sodium dendrite growth. Meanwhile, their coarse micron-scale fibrous framework provides sufficient space for dendrite penetration, posing severe safety risks. Herein, we developed a low-cost, mechanically robust, and environmentally sustainable bacterial cellulose/attapulgite (BC@ATP) composite separator via a facile papermaking-inspired fabrication strategy. Benefiting from its regulated ion transport and enhanced interfacial stability, Na||Na symmetric cells equipped with the BC@ATP separator exhibit stable cycling for over 1600 h at 1 mA cm−2. Meanwhile, full cells with sulfurized polyacrylonitrile (SPAN) deliver a high discharge specific capacity of 550 mAh g−1 after 600 cycles with an exceptional capacity retention of 98%. Notably, the separator is fabricated entirely from naturally derived, nontoxic materials, demonstrating its potential for sustainable battery separator applications. This work provides a viable strategy for developing high-performance sodium-metal battery separators that integrate mechanical robustness, electrochemical stability, and environmental sustainability.