Boric Acid Assisted Reduction of Graphene Oxide: A Promising Material for Sodium-Ion Batteries

Reduced graphene oxide, an intensively investigated material for Li-ion batteries, has shown mostly unsatisfactory performance in Na-ion batteries, since its d-spacing is believed to be too small for effective insertion/deinsertion of Na⁺ ions. Herein, a facile method was developed to produce boron-functionalized reduced graphene oxide (BF-rGO), with an enlarged interlayer spacing and defect-rich structure, which effectively accommodates the sodiation/desodiation and provides more active sites. The Na/BF-rGO half cells exhibit unprecedented long cycling stability, with ∼89.4% capacity retained after 5000 cycles (0.002% capacity decay per cycle) at 1000 mA·g^–1 current density. High specific capacity (280 mAh·g^–1) and great rate capability were also delivered in the Na/BF-rGO half cells.