Self-Supported FeCo2S4 Nanotube Arrays as Binder-Free Cathode for Lithium-Sulfur Batteries.

Inhibiting shuttle effect, buffering volume expansion and improving utilization of sulfur have been the three strategic points for developing a high-performance lithium-sulphur (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 binder-free cathode of the Li-S battery through two-step hydrothermal methods. 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 polysulfide due to their strong chemical adsorption. Meanwhile, the hollow structures of those arrays can provide a large inner space to accommodate 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 Coulomb efficiency of about 98%.