Large-scale synthesis of highly uniform Fe_1−xS nanostructures as a high-rate anode for sodium ion batteries

As a potential alternative to the prevailing lithium ion batteries, the application of sodium (Na) ion batteries (NIBs) in renewable energy and smart grid have revitalized research interest for large-scale energy storage. One of the roadblocks hindering their future commercialization is the development of suitable anode materials. Herein, we present the large-scale preparation of highly uniform iron sulfide (Fe_1−xS) nanostructures by a cost-effective and versatile one-step sulfurization strategy. Impressively, as a high-rate and viable sodium-ion anode, the as-prepared Fe_1−xS nanostructure manifests appealing electrochemical performance (a high discharge capacity of 563 mA h g⁻¹ over 200 cycles at a current density of 100 mA g⁻¹ and outstanding cycling stability even at high rate of 10 A g⁻¹ up to 2000 cycles). Moreover, the proven pseudocapacitance contribution interprets the unprecedented rate capability. Meanwhile, the sodium storage mechanism in the as-prepared samples has also been investigated by using the in-situ X-ray diffraction techniques. Remarkably, a full cell based on Na_0.6Co_0.1Mn_0.9O₂ cathode and Fe_1−xS anode deliver high discharge capacity (393 mA h g⁻¹) and superior cycling stability.