Separator Modified by Cobalt‐Embedded Carbon Nanosheets Enabling Chemisorption and Catalytic Effects of Polysulfides for High‐Energy‐Density Lithium‐Sulfur Batteries

Abstract

Lithium‐sulfur (Li‐S) batteries are considered to be one of the promising next‐generation energy storage systems. Considerable progress has been achieved in sulfur composite cathodes, but high cycling stability and discharging capacity at the expense of volumetric capacity have offset their advantages. Herein, a functional separator is presented by coating cobalt‐embedded nitrogen‐doped porous carbon nanosheets and graphene on one surface of a commercial polypropylene separator. The coating layer not only suppresses the polysulfide shuttle effect through chemical affinity, but also functions as an electrocatalyst to propel catalytic conversion of intercepted polysulfides. The slurry‐bladed carbon nanotubes/sulfur cathode with 90 wt% sulfur deliver high reversible capacity of 1103 mA h g−1 and volumetric capacity of 1062 mA h cm−3 at 0.2 C, and the freestanding carbon nanofibers/sulfur cathode provides a high discharging capacity of 1190 mA h g−1 and volumetric capacity of 1136 mA h cm−3 at high sulfur content of 78 wt% and sulfur loading of 10.5 mg cm−2. The electrochemical performance is comparable with or even superior to those in the state‐of‐the‐art carbon‐based sulfur cathodes. The separator reported in this work holds great promise for the development of high‐energy‐density Li‐S batteries.

Polyolefin‐Based Janus Separator for Rechargeable Sodium Batteries

“…As ar esult, the Na polysulfides could be intercepted and anchored on the cathode side,a nd the conductive DN-MXene coating layer could act as as econd current collector that enables reactivation and reutilization of the intercepted active materials. [31] Thecross-sectional image verifies that the DN-MXene coating layer is tightly attached to the PMTFSINa-grafted separator (Figure 4d;F igure S18). Thet hickness of such ac oating layer is approximately 3 mm and the areal mass loading is as low as approximately 0.04 mg cm À2 .…”

Inhibition of Polysulfide Shuttles in Li–S Batteries: Modified Separators and Solid‐State Electrolytes

“…The results of self‐discharge experiments showed that the capacity of the battery with Co–N–C/RGO/PP separator retained 91% after resting for 72h. Due to the enhanced utilization of sulfur species and accelerated redox kinetics, the cell displayed a high discharge capacity of 1344 mAh g −1 at 0.1 C with Coulombic efficiency over 98% and delivered excellent cyclability with a low capacity degradation of 28.8% after 500 cycles at 0.5 C. Afterward, Wang et al [ 117 ] coated cobalt‐embedded nitrogen‐doped porous carbon nanosheets and graphene on a commercial PP separator. Cobalt not only increases the polarity of carbon materials but also catalyzes the conversion of polysulfides.…”

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

“…It may induce the accumulation of the cathode products on the surface of the separator, rendering sluggish reaction kinetics and passive blockage of PSs. Incorporating catalytic component into the modified separator could offer a way for high‐efficient conversion …”

“…Incorporating catalytic component into the modified separatorc ould offer away forhigh-efficient conversion. [27]…”