Robust Solid-State Na-CO 2 Battery with Na 2.7 Zr 2 Si 2 PO 11.7 F 0.3 -PVDF-HFP Composite Solid Electrolyte and Na 15 Sn 4 /Na Anode.

Solid-state Na-CO 2 batteries are a kind of energy storage devices that can immobilize and convert CO 2 . 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 2 batteries. In this work, we investigate the influence of fluorine doping on the structure and ionic conductivity of Na 3 Zr 2 Si 2 PO 12 (NZSP). An ionic conductive solid electrolyte membrane was prepared by compositing the inorganic solid electrolyte Na 2.7 Zr 2 Si 2 PO 11.7 F 0.3 (NZSPF3) with poly(vinylidene fluoride)- co -hexafluoropropylene (PVDF-HFP). It shows an ionic conductivity of up to 2.17 × 10 -4 S cm -1 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 Na 15 Sn 4 /Na composite foil with the ability to inhibit dendrite as the anode for solid-state Na-CO 2 batteries. Through density functional theory (DFT) calculations, the Na 15 Sn 4 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 Na 15 Sn 4 /Na composite anode can inhibit the growth of Na dendrites effectively and maintain the stability of the whole cell structure. Solid-state Na-CO 2 batteries assembled with Ru-carbon nanotube (Ru-CNTs) as cathode catalysts exhibit a high discharge capacity of 6371.8 mAh g -1 at 200 mA g -1 , excellent cycling stability for 1100 h, and good rate performance. This work provides a promising strategy for designing high-performance solid-state Na-CO 2 batteries.