Ultralight Layer‐by‐Layer Self‐Assembled MoS₂‐Polymer Modified Separator for Simultaneously Trapping Polysulfides and Suppressing Lithium Dendrites

Abstract

Polysulfide shuttling and uncontrollable lithium dendrite growth have hampered the application of lithium–sulfur (Li–S) batteries. Although various materials have been utilized to overcome these obstacles, simple and scalable methods are still needed for Li–S battery commercialization. It is shown for the first time that the layer‐by‐layer (LbL) self‐assembly of 2D nanomaterials can be used to controllably fabricate multifunctional separators that simultaneously trap polysulfides and suppress lithium dendrite growth. The double‐sided “nanobrick wall” structure, constructed by MoS2/poly(diallyl dimethyl ammonium chloride) hybrid in conjunction with poly(acrylic acid) (PAA), provides a physical shield against polysulfides and the chemical adsorption of such species by MoS2 and PAA. At the same time, the robust and Li‐ion conducting MoS2 layers strengthen the separator and regulate Li deposition, thereby effectively suppressing Li dendrite formation. As a result, a simple sulfur cathode battery with an ultralight separator coating (0.10 mg cm−2) is able to achieve an outstanding cycle stability with a capacity decay as low as 0.029% per cycle over 2000 cycles and a reversible areal capacity ≈2.0 mAh cm−2 at 1 C. The proposed LbL approach opens the door to the simple, scalable, and economic fabrication of advanced functional separators for use in the real world.

Single Atom Array Mimic on Ultrathin MOF Nanosheets Boosts the Safety and Life of Lithium–Sulfur Batteries

“…As an indispensable component in a battery system, the routine separator can avoid the internal short circuit of cathode and anode while providing channels for ion transport. Given the sandwich configuration of cathode/separator/anode in cells, the functionalized separator could be a straightforward and reliable strategy to simultaneously inhibit shuttling effect and stabilize Li metal anode toward high‐performance Li–S batteries . Herein, we design a lightweight and flexible bifunctional separator (B/2D MOF‐Co), prepared by layer‐by‐layer (LBL) assembly of bacterial cellulose (BC) and 2D ultrathin MOF‐Co, for simultaneously regulating the Li stripping and plating behavior and polysulfide migration in Li–S batteries.…”

Two‐Dimensional MoS2 for Li−S Batteries: Structural Design and Electronic Modulation

“…Wu et al. designed a dual‐functional interlayer with good mechanical properties by coating self‐assembled few‐layered MoS 2 on the separator to simultaneously suppress lithium dendrite growth and LiPS shuttling . The Young's modulus of the interlayers was calculated by nanoindentation, as shown in Figure a.…”

“…SEM images and energy‐dispersive X‐ray (EDX) measurements of Li metal with c) pure separator and d) MoS 2 ‐coated separator. Reproduced with permission . Copyright 2018, Wiley‐VCH.…”

“…This strategy could open up a new window for the application of MoS 2 ‐functionalized separators in Li−S batteries. Subsequently, LBL self‐assembled few‐layered MoS 2 and polymers were also used to fabricate a functional separator, which could provide a physical shield against LiPS diffusion and strong chemical adsorption toward polysulfide species . As a result, a slow capacity decay rate of 0.029 % per cycle over 2000 cycles and a reversible areal capacity of about 2.0 mA h cm −1 at 1 C were achieved.…”

Highly Stable Lithium−Sulfur Batteries Promised by Siloxene: An Effective Cathode Material to Regulate the Adsorption and Conversion of Polysulfides

“…Besides, many 2D materials have been demonstrated to have unique sulfur species catalytic property, thus ameliorating the sluggish kinetics. Common polar 2D materials employed as sulfur host are molybdenum compounds (MoS 2 ,25,26 Sn 0.063 MoO 3 27), MXenes28 and their ramification,29 phosphorene,1 borophene,30 graphitic carbon nitride (C 3 N 4 , C 4 N 4 ),31,32 etc. Although these 2D materials are considered as ideal candidates for Li‐S cathodes, there are still some defects needed to be improved.…”