Multiscale Understanding of Covalently Fixed Sulfur–Polyacrylonitrile Composite as Advanced Cathode for Metal–Sulfur Batteries

Abstract

Metal–sulfur batteries (MSBs) provide high specific capacity due to the reversible redox mechanism based on conversion reaction that makes this battery a more promising candidate for next‐generation energy storage systems. Recently, along with elemental sulfur (S8), sulfurized polyacrylonitrile (SPAN), in which active sulfur moieties are covalently bounded to carbon backbone, has received significant attention as an electrode material. Importantly, SPAN can serve as a universal cathode with minimized metal–polysulfide dissolution because sulfur is immobilized through covalent bonding at the carbon backbone. Considering these unique structural features, SPAN represents a new approach beyond elemental S8 for MSBs. However, the development of SPAN electrodes is in its infancy stage compared to conventional S8 cathodes because several issues such as chemical structure, attached sulfur chain lengths, and over‐capacity in the first cycle remain unresolved. In addition, physical, chemical, or specific treatments are required for tuning intrinsic properties such as sulfur loading, porosity, and conductivity, which have a pivotal role in improving battery performance. This review discusses the fundamental and technological discussions on SPAN synthesis, physicochemical properties, and electrochemical performance in MSBs. Further, the essential guidance will provide research directions on SPAN electrodes for potential and industrial applications of MSBs.

In Situ Grown ZIF67 Particles on a Glass Fiber Separator: The Performance Booster and Anode Defender for Lithium–Sulfurized Polyacrylonitrile (SPAN) Batteries

“…Covalent bonding between the PAN matrix and sulfur particles hinders the LPS shuttle effect, and polysulfide dissolution directly results in the formation of Li 2 S. In addition, SPAN recompensed the volume expansion through cycling and utilized all the sulfur-active material. , The structure of SPAN is reversible through solid–solid conversion in carbonate and ether-based electrolytes; on the other hand, traditional sulfur systems show reversibility in ether-based systems only. The compatibility of carbonate electrolytes with SPAN systems results from the insolubility of the C–S bonds and Li 2 S discharge products . The GF separators were incorporated into our system to enhance the electrolyte uptake and maintain thermal stability.…”

“…The compatibility of carbonate electrolytes with SPAN systems results from the insolubility of the C−S bonds and Li 2 S discharge products. 34 The GF separators were incorporated into our system to enhance the electrolyte uptake and maintain thermal stability. The GF substrate's surface roughness boosted fillers or additive's adherence to the separator and improved ionic interactions with the SPAN cathode.…”

Quasi‐solid‐state conversion cathode materials for room‐temperature sodium–sulfur batteries

“…Sulfurized carbons may be described as active sulfur moieties chemically bound to an electronically conductive and nonreactive carbon backbone. 16 Wang et al 17 first demonstrated the viability of sulfurized pyrolyzed polyacrylonitrile (SPAN or S@pPAN) as a cathode material for Li-S systems. The composite with particulate morphology was prepared by heating polyacrylonitrile (PAN) in the presence of sulfur.…”

Disulfide Dichloride: A High Efficiency Vulcanizing Agent for Sulfurized Polyacrylonitrile

“…The solid−solid conversion cathode material represented by sulfurized polyacrylonitrile (SPAN) can fundamentally eliminate the shuttling effects and has received extensive research attention. 11,12 SPAN cathodes have shown great prospects in commercial applications due to the high discharge capacity, good cycle stability, and low self-discharge rate. The biggest advantage of the SPAN cathode is that soluble lithium polysulfides are not produced during the charge and discharge process, so as to eliminate the shuttling effects and improve the utilization of active substances.…”

“…Various attempts such as constructing a porous conductive network, , providing polar adsorption sites, , and introducing catalytic sites , have improved the utilization of active materials and inhibited the shuttle effect to a certain extent, but these problems cannot be eliminated fundamentally. The solid–solid conversion cathode material represented by sulfurized polyacrylonitrile (SPAN) can fundamentally eliminate the shuttling effects and has received extensive research attention. , …”