Design of novel Cu-doped SnS2 on carbon cloth as a binder-free anode to improve high-rate performance of sodium ion battery

Abstract

Tin disulfide (SnS₂) is a highly promising anode material for sodium-ion batteries (SIBs) due to its substantial theoretical capacity stemming from alloying reactions and conversion mechanisms. Eliminating non-conductive binders and simplifying fabrication, the binder-free SnS₂@carbon cloth (SnS₂@CC) electrode is gaining attention. In this study, a one-step solvothermal synthesis was applied to fabricate binder-free SnS₂@CC structures as SIB anodes. The electrochemical performance was enhanced by doping copper (Cu) into the SnS₂ lattice. Solvothermal duration and Cu doping levels were systematically investigated to optimize the electrochemical properties of anodes. The Cu-doped SnS₂@CC (Cu–SnS₂@CC) electrodes exhibited superior electrical conductivity and sodium ion diffusion coefficients compared to those for the SnS₂@CC electrodes. After 30 cycles, the Cu–SnS₂@CC electrode prepared using a 15-h solvothermal process and 2% Cu doping achieved the highest capacity of 1092.8 mA h g⁻¹ at 0.1 A g⁻¹, while the SnS₂@CC electrode yielded only 436.4 mA h g⁻¹ under the same conditions. The optimized Cu–SnS₂@CC electrode demonstrates excellent rate performance and cycling stability, with a capacity retention of 63% and Coulombic efficiency of 100% after 130 charge/discharge cycles. This research paves the way for high-performance, binder-free SnS₂-based anodes in SIBs.