A novel PbSe@CNTs anode material based on dual conversion-alloying mechanism for sodium-ion batteries

Sodium-ion batteries (SIBs) have been regarded as one of the most promising candidates for filling the application vacancy of lithium-ion batteries for large-scale electrical energy storage. However, anodes with high reversible capacities and fast reaction kinetics are lacking and must be investigated. In this study, a composite consisting of PbSe nanoparticles and carbon nanotubes (PbSe@CNTs) was prepared via a simple mechanical ball-milling method with the recovered Pb from lead-acid batteries and commercial Se powder. The introduced CNT networks can encompass and segregate PbSe nanoparticles, thus suppressing their aggregation and increasing the electronic conductivity. The nanosized PbSe and anfractuous CNTs benefit the electrolyte penetration, which shortens the diffusion distance of Na+ and electrons and relieves the strain upon the sodiation/desodiation process, resulting in an improved rate capability and long cycling. Therefore, the PbSe@CNTs electrodes exhibited a high reversible capacity of 597 mA h g−1 at 20 mA g−1 and 458.9 mA h g−1 for 100 cycles at 100 mA g−1 with a capacity retention of 88%. The two-step conversion-alloying mechanism of PbSe with Na to form Na2Se and Na15Pb4 was confirmed by ex situ X-ray diffraction and Raman spectroscopy. The results of this study provide valuable guidance for the design and synthesis of high-performance anodes for SIBs.