Synergistic Restriction to Polysulfides by a Carbon Nanotube/Manganese Sulfide-Decorated Separator for Advanced Lithium–Sulfur Batteries

Abstract

Polysulfide dissolution and shuttling limit the capacity output and cycle life of lithium−sulfur batteries to a great extent. Separator modification using polar materials exploiting the ability to entrap polysulfides has been demonstrated as an effective approach to deal with the conundrum of polysulfide shuttling. Herein, a carbon nanotube/manganese sulfide nanocomposite is designed as a separator modifier in lithium−sulfur batteries for the first time. Furthermore, the carbon nanotube network provides a continuous network for rapid electronic conduction, imparts structural stability, and acts as a secondary barrier for polysulfides. Consequently, the cell displays an initial discharge capacity of 876 mAh g −1 at 0.5 C and sustains excellent stability with a retained capacity of 76% after 500 cycles. The self-discharge of the cell is also conspicuously reduced, maintaining a constant voltage for 100 h under open-circuit conditions. The electrochemical results represent an effective strategy to realize better performing Li−S batteries.

Recent advances in modified commercial separators for lithium–sulfur batteries

“…Liu et al 237 synthesized 2D WS 2 nanosheets interwoven with 1D SWCNTs that formed a porous 3D structure that provided abundant active sites for polysulfide adsorption and conversion. In another example, Kannan et al 238 slurry coated a PP membrane with SWCNTs functionalized with MnS nanoparticles. The SWCNTs provided conductive pathways for polysulfide redox reactions while also physically blocking polysulfide shuttling.…”

Solutions to the Challenges of Lithium–Sulfur Batteries by Carbon Nanotubes

“…For example, a nanocomposite based on CNTs and manganese sulfide (MnS) has been applied as a separator modifier for LSBs, in which CNTs have multiple roles played during the operation, including acting as the scaffold for MnS nanograins, suppressing the shuttling of polysulfides, improving the electronic conduction and enhancing the mechanical strength of the separator. [143] In summary, ionic selectivity of the separator can be improved by hybridizing the CNT framework with (catalytic) species that are able to interact with polysulfides while the involvement of thermally stable additives can enhance the cycling performance of the membrane (and thus the resultant batteries) at elevated temperatures. In addition, interfacial engineering by creating porous architectures on the surface of separators is associated to the promoted wetting behavior of the liquid electrolytes.…”

Review and Perspectives on Advanced Binder Designs Incorporating Multifunctionalities for Lithium–Sulfur Batteries

“…Researchers have focused on various strategies for modifying different components of the battery, including cathode, − anode, − separators, − and electrolytes , to understand these issues . These modifications include immobilization of sulfur into certain conducting hosts, ,− inserting functional interlayers between cathode and separators, − separator modification, , using electrolyte additives, − etc.…”