Freestanding Fe_0.4Co_8.6S₈ Nanotube/Nanosheet Arrays on Carbon Cloth as a Host for High-Performance Li/SeS₂ Batteries

Abstract

To inhibit the shuttle effect and promote the electrochemical performance of the Li/SeS 2 batteries, the threedimensional (3D) conductive composite of freestanding Fe 0.4 Co 8.6 S 8 nanotube/nanosheet arrays on carbon cloth (CC@ Fe 0.4 Co 8.6 S 8 ) is designed and synthesized to host SeS 2 . The integrated host appears in the form of the Fe 0.4 Co 8.6 S 8 nanosheets growing on the surface of nanotubes supported by carbon cloth, which provides a great surface area and offers secondary protection from nanosheets against shuttle of polyselenides/sulfides on the basis of nanotubes. Such enhanced physical confinement, along with chemical immobilization of the polar Fe 0.4 Co 8.6 S 8 , ensures high capability to adsorb polyselenides/sulfides. The wellconstructed conductive network facilitates the fast redox reaction to lessen the dissolution and diffusion of polyselenides/sulfides. It was demonstrated by the adsorption test and explained by the systematic self-discharge experiments. As a result, upon the elevated current density and/or SeS 2 loading, the deliberately designed architecture of CC@Fe 0.4 Co 8.6 S 8 can exhibit large reversible capacity as well as great energy density. Specifically, with the areal loading of 2 mg cm −2 , the CC@Fe 0.4 Co 8.6 S 8 /SeS 2 electrode delivers high discharge capacity of 888 mAh g −1 at 1.0 A g −1 and excellent rate capability (585 mAh g −1 at 4.0 A g −1 ). In addition, with the areal loading increasing to 3.6 mg cm 2 , the cathode still reaches an ultrahigh capacity of 703 mAh g −1 at 1.0 A g −1 . Upon further increasing SeS 2 loading to 4.8 mg cm 2 , the corresponding areal energy density reaches 8.05 mWh cm −2 at 0.2 A g −1 . This contribution adopts a less complex structure to address the issues in Li/SeS 2 batteries. The effectiveness of shuttle inhibition is explained quantitatively through a systematic study on self-discharge phenomena, besides the electrochemical performance.

Rational Design of High‐Loading Electrodes with Superior Performances Toward Practical Application for Energy Storage Devices

“…Standard slurry-coating procedures can induce electrode cracking and detachment, culminating in battery malfunction. [18,36,42,43] In essence, the degradation of electrochemical performance under high-loading conditions stems from a combination of factors. The interplay of these elements hastens the performance decline.…”

“…[71] Carbon nanomaterials have gained popularity as matrix materials for these high-loading electrodes because of their excellent electrical conductivity and mechanical strength. [43,[72][73][74][75][76][77][78] To date, the primary strategies for the structure engineering of high-loading electrodes fall into three categories: 1. core-shell structure; 2. layered structure; and 3. low-tortuosity structure, which includes vertical channel structures and 3D conductive network structures.…”

“…This configuration showcased a remarkable areal capacity of 9.8 mAh cm −2 at 0.5 mA cm −2 and excellent rate performance (3.5 mAh cm −2 at 50 mA cm −2 ) with a high mass loading of 10 mg cm −2 . [112] In the context of Li-S [116,[133][134][135][136][137] and Li-Se batteries, [43,71,138,139] the design of a 3D conductive network structure can enhance sulfur utilization and cycling stability. This is achieved by physically restricting soluble lithium polysulfides within the cathode region, thereby mitigating the shuttle effect.…”

Advances in Selenium Sulfides Cathodes for Lithium/Selenium–Sulfur Batteries

“…This effectively curbed the intermediate shuttling, preserving a high rate capability (Figure d). In a different study, Liu and his team explored a two-phase hydrothermal method to cultivate FeCo 2 S 4 nanotube arrays on carbon cloth surfaces, as seen in Figure e . The freestanding carbon cloth@Fe 0.4 Co 8.6 S 8 structure facilitated fast redox reactions, reducing the shuttling of polysulfides/polyselenides.…”

“…(f) SEM image and (g) CV curve of CC@Fe 0.4 Co 8.6 S 8 . Reproduced with permission from ref . Copyright 2021 American Chemical Society.…”