With the growing interest in energy storage, significant research has focused on finding suitable anode materials for sodium-ion batteries (SIBs). While developing high-capacity nanosized metal sulfides, issues like low stability and rapid initial capacity decline are common. Instead of maintaining steady capacity, they also tend to exhibit an increase in discharge capacity as cycling continues. We introduce CNT-Cu2S, featuring Cu2S nanoplates integrated onto the surface of MWCNTs, and assess its electrochemical properties for SIBs. Cu2S initially exhibited a rapid decrease in capacity and then showed increased capacity. In contrast, CNT-Cu2S demonstrated a stable capacity of 344.8 mAh g-1 at 2.0 A g-1 over 800 cycles, close to the theoretical capacity with capacitive behavior. This paper carried out analysis using data from in situ EIS and overpotential data from GITT to explain the different outcomes between the Cu2S and CNT-Cu2S experiments. These results show that CNT-Cu2S is a suitable anode material for SIBs.
Keywords: Anode; Copper sulfide; In situ EIS; Multiwalled carbon nanotubes; Overpotential; Sodium-ion batteries.