Enhancing Sodium-Ion Transport in LTA Zeolite/PEO Composite Polymer Electrolytes through Cation Adsorption

The incorporation of ceramic fillers into polymer electrolytes has proven to be effective in bolstering their mechanical robustness, improving ionic transport efficiency, and ensuring enhanced interface integrity. Nonetheless, the current repertoire of suitable ceramic fillers for such applications is still somewhat limited. Zeolites, renowned for their pronounced adsorption capabilities and potential as sodium-ion conductors, have not been extensively studied regarding their impact on the electrochemical performance of composite electrolytes. In this work, we have developed a novel composite polymer electrolyte (CPE) based on poly(ethylene oxide) (PEO) integrated with LTA zeolite nanoparticles. The cation adsorption on the surface of LTA zeolite particles introduces additional ion migration pathways, while the interaction between hydroxyl groups and ether atoms of the PEO matrix weakens the coordination between Na⁺ and PEO, thereby promoting sodium-ion mobility within the LTA/PEO CPE. The synergistic effect of cation adsorption and Lewis acid–base action on the zeolite surface yields an impressive sodium-ion transference number of 0.44. The integration of the LTA zeolite into the composite electrolyte diminishes the interfacial resistance against sodium metal electrodes, effectively mitigating sodium dendrite formation. The NVP||PEO-10||Na battery incorporating 10 wt % LTA zeolites exhibits a capacity retention of nearly 88% after 100 cycles at 0.2 C, which is significantly better than those without the zeolite.