Novel paddy-like Bi-Sb-Cu alloy fabricated via pulse reverse potential electrodeposition enabling high-performance sodium-ion batteries

Sodium-ion batteries (SIBs) have gained remarkable interest as cost-effective and scalable energy storage devices. Nevertheless, their further application has been significantly hindered due to the limited selection of desirable anode materials that can provide both high capacity and excellent cycling stability. Herein, we developed a hierarchical paddy-like Bi42.3Sb35.2Cu22.5 alloy anode on Cu foil via template-free pulse reverse potential electrodeposition. The Bi42.3Sb35.2Cu22.5 anode obtains a considerable specific capacity of 529.5 mAh·g−1 after 120 cycles with a remarkable capacity retention of 95.5 %, signifying a capacity loss of only 0.0375 % per cycle. However, Bi44.9Sb55.1 anodes obtained by the pulse potential electrodeposition strategy reveal a conventional irregular cluster structure, delivering only 64.5 mAh·g−1 after 100 cycles and also demonstrating inferior rate performance compared to Bi42.3Sb35.2Cu22.5 anodes. The enhanced cycling performance of the paddy-like Bi42.3Sb35.2Cu22.5 anode is primarily attributed to the introduced Cu-doped network facilitating the rapid diffusion of Na+ and also ensuring the stability of the electrode structure. Moreover, the unique paddy-like structure of Bi42.3Sb35.2Cu22.5 mitigates volume expansion-related stress and facilitates efficient charge transport through open channels. This is further corroborated by conducting CV measurements, indicating a greater capacitive contribution in the case of the Bi42.3Sb35.2Cu22.5 electrode compared to the Bi44.9Sb55.1 electrode. Additionally, SEM images show a stabilized surface morphology for the Bi42.3Sb35.2Cu22.5 electrode after cycling, demonstrating improved electrochemical performance. This work offers new insights into the development of high-performance anode materials for SIBs.