Antimony-Coated Carbon Nanocomposites as High-Performance Anode Materials for High-Temperature Sodium-Metal Batteries

Metallic sodium (Na) possesses several advantageous characteristics, including a high theoretical specific capacity, low electrode potential, and availability in abundance, making it an ideal anode material for sodium-metal batteries (SMBs). However, the practical use of Na metal anodes is severely impeded due to the uncontrolled formation of dendrites due to the slow electrochemical kinetics and chemical instability of the formed solid-electrolyte interphase (SEI) layer. This situation can worsen considerably under high-temperature (HT) conditions (>55 °C). To overcome this issue, we have fabricated a thermally stable antimony (Sb)-coated carbon (Sb@C) nanocomposite as a sodium host material, where Sb nanoparticles are encapsulated within the carbon layers. This unique nanostructure controls vaporization during the plating-stripping process and dendrite formation and provides acceptor sites for Na⁺ ions. The Sb@C electrode exhibits an extended life span of symmetrical cycles (2400 h at 1 mA cm^-2) due to the abundant nucleation sites. It maintains a low nucleation overpotential (∼15 mV), enhancing its performance and long cycle stability. Moreover, the in situ formed Na-Sb synergistically offers durable ionic/electronic diffusion paths and chemically interacts with Na, forming abundant Na nucleation sites. Therefore, in this study, we emphasize the importance of the rational design of highly stable alloys and present an effective strategy for achieving high-performance sodium-metal anodes.