Enhanced Sulfur Transformation by Multifunctional FeS₂/FeS/S Composites for High‐Volumetric Capacity Cathodes in Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries are currently being explored as promising advanced energy storage systems due to the high theoretical specific capacity of sulfur. However, achieving a scalable synthesis for the sulfur electrode material whilst maintaining a high volumetric energy density remains a serious challenge. Here, a continuous ball‐milling route is devised for synthesizing multifunctional FeS 2 /FeS/S composites for use as high tap density electrodes. These composites demonstrate a maximum reversible capacity of 1044.7 mAh g −1 and a peak volumetric capacity of 2131.1 Ah L −1 after 30 cycles. The binding direction is also considered here for the first time between dissolved lithium polysulfides (LiPSs) and host materials (FeS 2 and FeS in this work) as determined by density functional theory calculations. It is concluded that if only one lithium atom of the polysulfide bonds with the sulfur atoms of FeS 2 or FeS, then any chemical interaction between these species is weak or negligible. In addition, FeS 2 is shown to have a strong catalytic effect on the reduction reactions of LiPSs. This work demonstrates the limitations of a strategy based on chemical interactions to improve cycling stability and offers new insights into the development of high tap density and high‐performance sulfur‐based electrodes.

A Combined Ordered Macro‐Mesoporous Architecture Design and Surface Engineering Strategy for High‐Performance Sulfur Immobilizer in Lithium–Sulfur Batteries

“…[ 10 ] Furthermore, TMSs are favorable in achieving fast ion/electron transfer process for sulfur cathode owing to its high conduction properties. [ 11 ] Therefore, a selection of sulfur host material with decent ion/electron conduction, proper structural design with enhanced structural stability and abundant LiPS trapping/catalytic active sites is essential in the development of high‐performance Li–S batteries.…”

Electrode Design for Lithium–Sulfur Batteries: Problems and Solutions

“…Beyond that, some special chemical reactions can also be triggered by ball milling method to achieve new sulfur‐based composite cathodes. Xi et al [ 81 ] reported a simple ball milling method to synthesize multifunctional FeS 2 /FeS/S as LSBs cathode with high tap density. The redox reaction between Fe 3+ and S x 2− was achieved with consecutive ball‐milling process.…”

A microporous carbon derived from metal‐organic frameworks for long‐life lithium sulfur batteries

“…6,7 However, the insulativity of active sulfur and discharge product (Li 2 S), the solubility of discharge intermediates (Li 2 S x , 4 ≤ x < 8) into organic electrolyte, and the "shuttle effect" by diffusing polysulfides into the negative electrode to produce parasitic reactions, cause serious active sulfur loss from cathode and cycle deterioration of the batteries, greatly hindering the Li-S batteries' development and commercialization. [8][9][10] In order to address these issues, significant progresses have been made in the last decade by immobilizing sulfur within various host materials to form sulfur-based composites, like sulfur/carbon composites, [11][12][13][14][15][16][17][18] sulfur/metallic compounds composites, [19][20][21][22][23][24][25][26] and sulfur/polymer composites. [27][28][29][30][31] It is noted that among the various host materials, microporous carbon is quite distinctive, because esterbased electrolyte was usually used for sulfur/microporous carbon (S/MC) composites based Li-S batteries, while ether-based electrolyte was commonly used in other composites based Li-S battery systems.…”

“…In order to address these issues, significant progresses have been made in the last decade by immobilizing sulfur within various host materials to form sulfur‐based composites, like sulfur/carbon composites, sulfur/metallic compounds composites, and sulfur/polymer composites . It is noted that among the various host materials, microporous carbon is quite distinctive, because ester‐based electrolyte was usually used for sulfur/microporous carbon (S/MC) composites based Li‐S batteries, while ether‐based electrolyte was commonly used in other composites based Li‐S battery systems.…”