Artificially Layered CoSe2 Nanosheets by a Dual-Templating Strategy for High-Performance Lithium-Sulfur Batteries.

Abstract

Owing to the attractive merits of layered transition metal dichalcogenides (LTMDs) with van der Waals interactions, it is significant to modulate electronic structures and endow them with fascinating physiochemical properties by converting a nonlayered metal dichalcogenide into an atomic layered one. Herein, a dual-templating strategy is designed to prepare artificially layered CoSe2 nanosheets on carbon fiber cloth (L-CoSe2/CFC). It is found that not only the nanosheet morphology but also the layered structure is well inherited from the precursor of layered Co(OH)2 nanosheets through a wet-solution ion-exchange approach. The as-prepared L-CoSe2/CFC serves as an efficient multifunctional interlayer to solve the challenges of "shuttling effect" and slow multistep reaction kinetics in lithium-sulfur batteries (LSBs), thus dramatically improving their electrochemical performance. Benefiting from the L-CoSe2 nanosheets with large interlayer spacing, strong chemical adsorption, and superior catalytic activity, L-CoSe2/CFC promotes the anchoring of lithium polysulfides (LiPSs) and their catalytic conversion. Consequently, the L-CoSe2/CFC cell yields a large reversible capacity of 1584 mAh g-1 at 0.2C and a high rate capability of 987 mAh g-1 at 4C. A high areal capacity of 4.38 mAh cm-2 after 100 cycles at 0.2C is achieved for the high-S-loading LSB (4.6 mg cm-2) using the L-CoSe2/CFC interlayer.