Immiscible alloys as high-capacity and ultra-stable anodes for sodium-ion batteries

Abstract

Alloy-type anodes are considered promising candidates for sodium-ion batteries (SIBs) due to their high theoretical capacities, low discharge plateaus, and abundant resources. However, the significant volume changes of the electrode during discharging/charging result in particle pulverization and continuous electrolyte consumption, leading to increased interfacial impedance and degradation of electrochemical performance. Herein, an immiscible alloy (Pb₃₂Bi_52.5Sn_15.5, PBS) with an interlocking structure was developed at a mild temperature and used as the anode for SIBs. The multicomponents of PBS enable rapid electron conduction and fast Na⁺ diffusion throughout the cycles, mitigating voltage hysteresis to reduce polarization and increase energy utilization efficiency. The PBS anodes exhibit exceptional electrochemical properties, including a high-reversible capacity of 522.6 mA h g⁻¹ at 50.0 mA g⁻¹ and stable cycling performance with a capacity retention rate of 86.9% after 10 000 cycles at 5.0 A g⁻¹. This innovative approach and impressive performance of immiscible alloys pave a new way for developing high-performance anode materials for SIBs and beyond.