Tin nanoparticle in-situ decorated on nitrogen-deficient carbon nitride with excellent sodium storage performance

The combination of nitrogen-deficient C 3 N 4 and ultrasmall Sn with excellent ion diffusion kinetics enables excellent sodium storage performance. • A unique 3D decorated structure containing ultrafine Sn and N -doped layered carbon was successfully fabricated through a facile bottom-up method. • The significant improvement in sodium-ion diffusion kinetics for D-CN is proved by DFT. • Superior cycling stability and remarkable rate capability are achieved as anode for sodium-ion half and full batteries. Tin (Sn)-based electrodes, featuring high electrochemical activity and suitable voltage plateau, gain tremendous attention as promising anode materials for sodium-ion batteries. However, the application of Sn-based electrodes has been largely restricted by the serious pulverization upon repeated cycling due to their large volume expansion, especially at high current densities. Herein, a unique three-dimensional decorated structure was designed, containing ultrafine Sn nanoparticles and nitrogen-deficient carbon nitride (Sn/D-C 3 N 4 ), to efficiently alleviate the expansion stress and prevent the aggregation of Sn nanoparticles. Furthermore, the density functional theory calculations have proved the high sodium adsorption ability and improved diffusion kinetics through the hybridization of D-C 3 N 4 with Sn nanoparticles. Further combining the high electronic/ionic conductivity provided by the porous C 3 N 4 matrix, high charge contribution from capacitive behavior, and high sodium storage activity of ultrafine Sn nanoparticles, the resultant Sn/D-C 3 N 4 can achieve an ultrahigh reversible capacity of 518.3 mA g −1 after 300 cycles at 1.0 A g −1 , and even maintaining a reversible capacity of 436.1 mAh g −1 up to 500 cycles (5.0 A g −1 ). What’s more, the optimized Sn/D-C 3 N 4 ∥Na 3 V 2 (PO 4 ) 3 /C full cell can keep a high capacity retention of 87.1% at 1.0 A g −1 even after 5000 cycles, manifesting excellent sodium storage performance.