Construction of Inorganic/Organic Hybrid Layer for Stable Na Metal Anode Operated under Wide Temperatures

Abstract Sodium metal battery is supposed to be a propitious technology for high‐energy storage application owing to the advantages of natural abundance and low cost. Unfortunately, the uncontrollable dendrite growth critically hampers its practical implementation. Herein, an inorganic/organic hybrid layer of NaF/CF/CC on the surface of Na foil (IOHL‐Na) is designed and synthesized through the in situ reaction of polyvinylidene fluoride (PVDF) and metallic sodium. This protective layer possesses satisfactory Young's modulus, good kinetic property, and sodiophilicity, which can distinctly stabilize Na metal anode. As a result, the symmetric IOHL‐Na cell achieves a lifespan of 770 h at 1 mAh cm −2 /1 mA cm −2 in carbonate electrolyte. The assembled full battery of IOHL‐Na||Na 3 V 2 (PO 4 ) 3 delivers a high discharge capacity of 85 mAh g −1 at 10 C after 600 cycles under ambient temperature. Furthermore, the IOHL‐Na||Na 3 V 2 (PO 4 ) 3 cell still can steadily operate at 10 C for 600 cycles at 55 °C. And when testing at an ultralow temperature of −40 °C, the full cell achieves 40 mAh g −1 at 0.5 C with a prolonged lifespan of 450 cycles. This work offers a new approach to protect the metal sodium anode without dendrite growth under wide temperatures.