Robust Solid-State Na-CO Battery with NaZrSiPOF-PVDF-HFP Composite Solid Electrolyte and NaSn/Na Anode.

Solid-state Na-CO batteries are a kind of energy storage devices that can immobilize and convert CO. They have the advantages of both solid-state batteries and metal-air batteries. High-performance solid electrolyte and electrode materials are important for improving the performance of solid-state Na-CO batteries. In this work, we investigate the influence of fluorine doping on the structure and ionic conductivity of NaZrSiPO (NZSP). An ionic conductive solid electrolyte membrane was prepared by compositing the inorganic solid electrolyte NaZrSiPOF (NZSPF3) with poly(vinylidene fluoride)--hexafluoropropylene (PVDF-HFP). It shows an ionic conductivity of up to 2.17 × 10 S cm at room temperature, a high sodium ionic transfer number of ∼0.70, a broad electrochemical window of ∼5.18 V, and better mechanical strength. Furthermore, we studied the NaSn/Na composite foil with the ability to inhibit dendrite as the anode for solid-state Na-CO batteries. Through density functional theory (DFT) calculations, the NaSn particle has been verified with a strong sodiophilic property, which reduces the nucleation barrier during the deposition process, leading to a lower overpotential. The symmetric cell assembled with the composite solid-state electrolyte NZSPF3-PVDF-HFP and NaSn/Na composite anode can inhibit the growth of Na dendrites effectively and maintain the stability of the whole cell structure. Solid-state Na-CO batteries assembled with Ru-carbon nanotube (Ru-CNTs) as cathode catalysts exhibit a high discharge capacity of 6371.8 mAh g at 200 mA g, excellent cycling stability for 1100 h, and good rate performance. This work provides a promising strategy for designing high-performance solid-state Na-CO batteries.