Definable Two-Dimensional Mesoporous Polydopamine-Graphene Heterostructure as Multi-Functional Ion Redistributor for Ultrastable Sodium Metal Anodes

Abstract

Sodium metal batteries are widely acknowledged as one of the most promising low-cost high-energy-density batteries, but limited by uncontrollable dendritic growth and short cyclability. Herein, two-dimensional (2D) mesoporous polydopamine-graphene (mPG) heterostructures with definable pore size and sheet thickness are demonstrated as multi-functional ion redistributors to realize ultrastable, dendrite-free Na metal anodes. Benefitting from abundant sodiophilic groups (-OH, C=O and -NH-), 2D nanoporous graphene, and ordered mesoporous ion channels in mPG, the Na metal anodes show high Coulombic efficiency of >99.5%, outstanding cyclability of ~2000 h, and unprecedented rate performance of 25 mA cm-2 with 25 mAh cm-2, outperforming all the reported Na anodes stabilized by diversified strategies. What’s more, the mPG based Na/Na3V2(PO4)3 full batteries deliver exceptionally enhanced cyclability (90% retention rate after 500 cycles) and rate capacity (75 mAh g-1 at 30 C), demonstrative of impressive potential of well-designed 2D mesoporous polymers for precisely regulating Na deposition.