Mechanistic understanding of the role separators playing in advanced lithium‐sulfur batteries

Abstract

The lithium-sulfur battery is considered one of the most promising candidates for portable energy storage devices due to its low cost and high energy density.However, many critical issues, including polysulfide shuttling, self-discharge, lithium dendritic growth, and thermal hazards need to be addressed before the commercialization of lithium-sulfur batteries. To this end, tremendous efforts have been made to explore battery configurations and components, such as electrodes, electrolytes, and separators, among which the separator plays an especially critical role in addressing aforementioned issues. Thus, this review analyzes the mechanisms and interactions of these critical issues and summarizes both the function of separators and recent progress made towards remedying such issues. Additionally, promising directions for the development of separators in lithium-sulfur batteries are proposed. K E Y W O R D Slithium dendrite, lithium-sulfur batteries, self-discharge, separator, shuttle effect, thermal hazardsThe first two authors contributed equally to this work.

Optimizing Redox Reactions in Aprotic Lithium–Sulfur Batteries

“…The typical configuration of aprotic Li–S battery is assembled using Li metal anode and porous cathode for hosting the S. A separator is configured between the two electrodes in which aprotic electrolyte is introduced ( Figure 1 a). [ 14,15 ] During the discharge process, Li anode undergoes oxidization to form Li + which migrate from anode to cathode through the electrolyte. At cathode side, Li + reacts with S to form Li 2 S via receiving electrons from the outer electrical circuit.…”

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

“…Many strategies have been used to inhibit polysulfide shuttle including designing nanostructured composite sulfur cathodes, adding polar materials or functional groups on sulfur cathodes, modifying separators by various coatings, and replacing liquid electrolytes with solid‐state electrolytes. [ 11–16 ] Yu and co‐workers [ 4 ] reviewed the mechanisms and improvement strategies in inhibiting polysulfide diffusion mainly focusing on sulfur cathodes and separators. Wang group [ 17 ] discussed various preparation methods for the cathode materials and separators in LSBs.…”

Defective Graphitic Carbon Nitride Modified Separators with Efficient Polysulfide Traps and Catalytic Sites for Fast and Reliable Sulfur Electrochemistry

“…[ 2 ] In principle, insufficient inhibition toward LiPSs will lead to the so‐called shuttle effect, which causes LiPSs diffusing out of the cathode side and eventually migrating through the membrane to react with the lithium anode, triggering the rapid/irreversible capacity loss. [ 2 ] Therefore, researchers are committed to various solutions such as well design of polar host, [ 3 ] addition of contributing binder/electrolyte, [ 4,5 ] and cell configuration modifications (e.g., introduction of interlayer, and functionalization of separator) [ 6 ] to realize the controllable LiPSs regulation. Among these strategies, the functionalization of separator is regarded as one of the most efficient approaches to relieve the capacity attenuation of LSBs.…”

“…For example, due to fact that the majority of sulfur cathodes consist of significant amounts of host materials (normally carbon), [ 2 ] the addition of large amounts of binder or conductive filler in the separator coatings deprecates the cell‐level specific energy. [ 4,6,9 ] Additionally, investigating isolated device or system while ignoring the actual operating status is no longer sufficient to tackle technological challenges involved in the development of the application‐oriented LSBs, the design of separators should be able to meet researchers’ assumption of lightweight and favorable stability.…”