Preparation of a Novel g-C<inf>3</inf>N<inf>4</inf>/Sn/N-doped Carbon Composite for Sodium Storage

Sodium-ion batteries(SIBs) based on Sn-based anodes have attracted increasing attention due to their high theoretical capacity(847 mA•h/g), high electrical conductivity and suitable operation potential. Unfortunately, the huge structural change upon cycling often causes particle pulverization and rapid capacity decay. In this work, ultrafine Sn nanoparticles with dual protection from graphitic carbon nitride(g-C3N4) and polydopamine derived N-doped carbon(g-C3N4/Sn/NC) were successfully fabricated through a designed strategy. Generally, the introduction of g-C3N4 and NC can dramatically accelerate the transport of electrons/ions as well as the reaction dynamics, thus contributing to the alloying reaction between Sn and Na+. Importantly, the ultrafine Sn as well as the dual buffering matrices can efficiently maintain the integrity of electrode upon cycling, guaranteeing the superior electrochemical performance. Benefitting from the structural advantages inhe-rited from the ultrafine Sn nanoparticles and dual protection scaffolds, the as-obtained g-C3N4/Sn/NC displays excellent sodium storage performances, with high reversible capacity(450.7 mA•h/g at 0.5 A/g after 100 cycles), remarkable rate capability(388.3 mA•h/g at 1.0 A/g) and stable long-term cycling stability(363.3 mA•h/g after 400 cycles at 1.0 A/g)