A novel nitrogen-doped carbon-coated SnSe2 based on post-synthetic modified MOF as high-performance anode materials for lithium-ion batteries and sodium-ion batteries

Abstract

SnSe2 with high theoretical capacity has been identified as an emerging anode candidate for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, the rate and cycling performance of this material in practical applications is still limited by unavoidable volume expansion and low conductivity. In this paper, Sn-MOF was modified using 2-aminoterephthalic acid (C8H7NO4) to replace solvent sites in MOF clusters to improve electrochemical stability, for improving conductivity heat-treated with selenium powder to synthesize nitrogen-doped carbon-coated SnSe2/C-N composites. The inherited carbon skeleton from Sn-MOF precursor can alleviate the volume expansion of SnSe2/C-N during cycling. N-doping in Sn-MOF can increase the positive and negative electrostatic potential energy regions on the molecular surface to further improve the electrical conductivity, and effectively reduce the binding energy with Li+/Na+ which obtained by Density Functional theory (DFT) methods. In addition, N-doping carbon skeleton also introduces a larger space for Li+/Na+ intercalation and enhance the mechanical properties. In particular, the post-synthesis modified MOF-derived SnSe2/C-N materials exhibit excellent cyclability, with a reversible capacity of 695 mAh·g-1 for LIB and 259 mAh·g-1 for SIB after 100 cycles at 100 mA·g-1.