Ultrafine ZnSe Encapsulated in Nitrogen-Doped Porous Carbon Nanofibers for Superior Na-Ion Batteries with a Long Lifespan and Low-Temperature Performance

The inferior cycle lifespan and unsatisfactory energy density of traditional anode materials for sodium-ion batteries need to be improved toward actual application. Here, MOF-derived ultrafine ZnSe nanoparticles encapsulated within nitrogen-doped porous carbon nanofiber composites (ZnSe@NCNFs) are fabricated via in situ pyrolysis and selenylation from electrospun PAN@ZIF-8 nanofibers. As an anode, the ZnSe@NCNF electrode displays outstanding sodium-storage performance and superior cycling stability (197.3 mAh g–1 after 1700 cycles at 10 A g–1). Remarkably, the assembled SIBs work well in low temperatures within the range from −20 to −40 °C, showing the prospect for energy storage in an extreme environment. The impressive electrochemical properties are primarily due to the peculiar porous framework and ultrafine ZnSe nanoparticles, as well as a robust N-doped carbon matrix, which provide a penetrating network for fast ion/electron transfer and alleviate the pulverization of ZnSe during a sodiation/desodiation reaction. Moreover, the underlying reaction mechanism and outstanding reversibility of the ZnSe@NCNF electrodes are systematically revealed through ex situ X-ray diffraction/scanning electron microscopy (XRD/SEM) analysis and dynamic analysis.