Self-Supported FeCo₂S₄ Nanotube Arrays as Binder-Free Cathodes for Lithium–Sulfur Batteries

Abstract

Inhibiting the shuttle effect, buffering the volume expansion, and improving the utilization of sulfur have been the three strategic points for developing a high-performance lithium-sulfur (Li-S) battery. Driven by this background, a flexible sulfur host material composed of FeCo₂S₄ nanotube arrays grown on the surface of carbon cloth is designed for a binder-free cathode of the Li-S battery through two-step hydrothermal method. Among the rest, the interconnected carbon fiber skeleton of the composite electrode ensures the basic electrical conductivity, whereas the FeCo₂S₄ nanotube arrays not only boost the electron and electrolyte transfer but also inhibit the dissolution of polysulfides because of their strong chemical adsorption. Meanwhile, the hollow structures of these arrays can provide a large inner space to accommodate the volume expansion of sulfur. More significantly, the developed composite electrode also reveals a catalytic action for accelerating the reaction kinetic of the Li-S battery. As a result, the FeCo₂S₄/CC@S electrode delivers a high discharge capacity of 1384 mA h g^-1 at the current density of 0.1 C and simultaneously exhibits a stable Coulombic efficiency of about 98%.