Nip the Sodium Dendrites in the Bud on Planar Doped Graphene in Liquid/Gel Electrolytes

Sodium (Na) metal is the most promising alternative anode to metallic lithium for high-energy batteries due to the low cost and high abundance of Na resources, but it suffers from severe dendritic/mossy growth at high current densities. Understanding Na nucleation/growth mechanism in different electrolyte systems is the key to tackling this issue but is complicated by the structural complexities of existing substrates for Na plating/stripping. Herein, well-defined planar doped graphene substrates are synthesized as model plating platforms to unravel a binding energy dominant Na nucleation-growth mode. The dopants (e.g., boron) in doped graphene and the regions close to the dopants possess high binding energies with Na atoms, providing abundant preferential nucleation sites and contributing to uniform Na plating/stripping. Accordingly, the boron-doped graphene regulated Na anode exhibits long-term stability at high current densities in both liquid and polymer electrolytes. The results enhance the understanding of Na nucleation/growth for stabilizing Na metal batteries.