Atom-Thick Interlayer Made of CVD-Grown Graphene Film on Separator for Advanced Lithium–Sulfur Batteries

Abstract

Lithium-sulfur batteries are widely seen as a promising next-generation energy-storage system owing to their ultrahigh energy density. Although extensive research efforts have tackled poor cycling performance and self-discharge, battery stability has been improved at the expense of energy density. We have developed an interlayer consisting of two-layer chemical vapor deposition (CVD)-grown graphene supported by a conventional polypropylene (PP) separator. Unlike interlayers made of discrete nano-/microstructures that increase the thickness and weight of the separator, the CVD-graphene is an intact film with an area of 5 × 60 cm and has a thickness of ∼0.6 nm and areal density of ∼0.15 μg cm, which are negligible to those of the PP separator. The CVD-graphene on PP separator is the thinnest and lightest interlayer to date and is able to suppress the shuttling of polysulfides and enhance the utilization of sulfur, leading to concurrently improved specific capacity, rate capability, and cycle stability and suppressed self-discharge when assembled with cathodes consisting of different sulfur/carbon composites and electrolytes either with or without LiNO additive.

Two‐Dimensional Material‐Functionalized Separators for High‐Energy‐Density Metal–Sulfur and Metal‐Based Batteries

“…To avoid a much increase of weight and thickness after modification, Du et al. developed a PP separator covered by atom‐thick chemical vapor deposition (CVD)‐grown graphene (Figure a) . The LSB with ultrathin graphene‐coated separator had a specific capacity of 1460 mAh g −1 at 0.1 C. As shown in Figure b, it maintained 69 % of its initial capacity after 1500 cycles at 0.5 C, compared to 25 % for the LSB with original separator.…”

“…b) Cycling performance of Li−S cells assembled with either bare PP or ultrathin graphene‐coated PP. Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…When applied in LSBs, Reproduced with permission. [19] Copyright2 017,American Chemical Society.c)Schematic illustration and SEM images of aP Ps eparator coated by N-doped porous carbon nanosheets.d )Stablec ycling performanceo fLSB utilizingt he functional separatora t 0.5 C. Reproducedw ith permission. [23] Copyright 2018, ElsevierI nc.…”

Separator Membranes for Lithium–Sulfur Batteries: Design Principles, Structure, and Performance

“…Jiang et al synthesized GO sheets and coated a commercial Celgard 2400 membrane with it via the tape casting method to achieve a functional separator for Li‐S systems . Du et al grew graphene via the chemical vapor deposition (CVD) method and then transferred a bilayer graphene film onto a commercial polypropylene separator to suppress the polysulfide shuttle through steric exclusion . The intact film of CVD‐grown graphene was unlike the other coating layers utilized in the Li‐S system, as the thickness and areal density of the introduced layer were extremely small, negligible as compared to the pristine separator.…”

Calixarene‐Functionalized Porous Carbon Aerogels for Polysulfide Capture: Cathodes for High Performance Lithium‐Sulfur Batteries

“…The ACA was obtained by activating CA. Typically, 45.0 g KOH, 10.0 g CA and 10 ml deionized water were mixed and activated at 700°C for 3 hours under a N 2 atmosphere. The resulting material was neutralized with hydrochloric acid (6 M) and washed with deionized water four times.…”