Enhanced Long-Term Stability of Zinc-Air Batteries Using a Quaternized PVA-Chitosan Composite Separator with Thin-Layered MoS2

Abstract

Due to their high energy density and cost-effectiveness, rechargeable zinc-air batteries (ZABs) are increasingly recognized for their potential as long-duration energy storage solutions. A crucial component for maximizing their efficiency is the membrane separator, which must exhibit high hydroxide-ion conductivity and long-term stability. This study introduces an innovative hybrid composite separator, created by embedding thin-layered molybdenum disulfide (MoS₂), known for its intrinsic negative charge, into a polycationic quaternized PVA-chitosan (CS) matrix. Polyvinyl alcohol (PVA) is functionalized with quaternary ammonium (QA) groups before being combined with CS and MoS₂, using a solvent blending technique. The separator's three-dimensional structure and morphology is analyzed via synchrotron radiation X-ray tomographic microscopy (SR-XTM). Results demonstrate that the ZAB equipped with a quaternized PVA/CS/0.5 wt.% MoS₂ composite separator achieved a high conductivity of 87.3 mS cm^-1 and exceptional stability, enduring over 465 cycles. This performance is attributed to the synergistic interaction between the quaternized PVA-CS matrix and the MoS₂ surface, forming robust polymer complexes through electrostatic interactions. These findings suggest that the developed separators hold significant promise for advanced ZAB applications.