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 highperformance lithium−sulfur (Li−S) battery. Driven by this background, a flexible sulfur host material composed of FeCo 2 S 4 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 FeCo 2 S 4 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 FeCo 2 S 4 /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%.

Hierarchical FeCo2S4@FeNi2S4 Core/Shell Nanostructures on Ni Foam for High‐Performance Supercapacitors

“…Many previous efforts focused on designing nanostructures such as nanowires, nanotubes, nanorods, and nanosheets to improve the utilization efficiency of electroactive sites of electrode materials. In addition, growing capacitive materials directly on conducting porous substrates such as Ni foam to fabricate binder‐free electrodes is also a convenient way to increase the electrode/electrolyte interaction and ion transport, as well as improve electrical conductivity and mechanical stability .…”

Recent Progress in Binder‐Free Electrodes Synthesis for Electrochemical Energy Storage Application

“…Among them, carbon fibers are one popular electrode substrate due to their high electrical conductivity, chemical inertness and flexibility [77] . Carbon fiber‐based electrodes have been widely adopted in lithium‐sulfur batteries, [78–79] lithium‐ion batteries, [80–81] sodium‐ion batteries, [82–83] supercapacitors, [84–85] etc. For instance, Ma et al [86] .…”

Recent Advances of Freestanding Cathodes for Li‐S Batteries

“…Consequently, the Li−S battery used this cathode showed a capacity degradation rate of only 0.08% per cycle after 150 cycles at 0.2 C even at a high sulfur loading of 7.11 mg cm −2 (Figure 6b). A self‐supported FeCo 2 S 4 nanotube arrays grown on CC were developed to encapsulate sulfur for LBSs ( Figure 6c) [71] . The interconnected carbon fiber backbone in the electrode enables high electrical conductivity, while the FeCo 2 S 4 nanotube arrays facilitate electron and electrolyte transfer, and inhibit the polysulfides shuttle due to their strong chemisorption.…”