A Polysulfide-Repulsive, In Situ Solidified Cathode–Electrolyte Interface for High-Performance Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries are promising candidates for beyond-Li-ion electrochemical energy storage yet are hindered due to limited cycle lives. In case a liquid ether electrolyte is used, the S cathode suffers from an unstable electrode–electrolyte interface, at which soluble polysulfide intermediates form, dissolve, and shuttle between the two electrodes. When the cathode–electrolyte interface is solidified, the S cathode shows suppressed polysulfide dissolution. In this work, we show that a liquid polymer cathode additive, poly(hexamethylene diisocyanate), is able to react with soluble polysulfide species at the beginning of battery discharge to in situ form a solidified, polysulfide-anion-grafted organic cathode–electrolyte interface. In addition to serving as a physical barrier, the negatively charged interface helps to anchor polysulfides at the cathode surface via electrostatic repulsion. The solidified interface around the active S particles also forms an efficient, three-dimensional porous Li-ion conducting network to trigger improved electrode kinetics and avoid the formation of locally dead S. Benefiting from the improved interfacial electrochemistry, the Li–S battery shows admirable storage performance in terms of cycle life and rate capability to promise practical high-energy rechargeable batteries.

Azobenzene‐Based Conjugated Polymers: Synthesis, Properties, and Biological Applications

“…Light can be precisely manipulated with high spatial and temporal accuracy, prompting researchers to extensively explore various photoresponsive compounds for applications in life sciences research. [41] Among these, azobenzene is one of the most popular and reliable photoisomerizing molecular functional group. Azobenzene derivatives undergo a clean photoisomerization reaction when irradiated with UV light at 340 nm, converting the stable rod-like trans-isomer into the globular, metastable cis isomer, and vice versa.…”

Coordinated Immobilization and Rapid Conversion of Polysulfide Enabled by a Hollow Metal Oxide/Sulfide/Nitrogen‐Doped Carbon Heterostructure for Long‐Cycle‐Life Lithium‐Sulfur Batteries

“…The shuttle effect in LSBs inevitably leads to the harmful side reactions between lithium polysulfide and Li anode, and induces the severe anode corrosion and rapid battery failure. [59][60][61][62] Thus, the morphologies of lithium anodes in LSBs with S-CoO/ Co 9 S 8 /NC, S-Co 9 S 8 /NC, and S-CoO/NC after 100 cycles at 0.1 C were characterized by SEM images and digital photos to discuss the effect of different hosts on inhibiting the shuttle of LiPSs. Figure S32, Supporting Information, shows digital photos and SEM images of Li anodes after cycling.…”

Cathode Kinetics Evaluation in Lean-Electrolyte Lithium–Sulfur Batteries

“…Lithium–sulfur (Li–S) batteries are considered as one of the most promising battery systems to achieve actual high energy density due to their ultrahigh theoretical energy density of 2600 Wh kg –1 . − Typical Li–S batteries employ elemental sulfur as the cathode, lithium metal as the anode, and use ether-based electrolyte. The sulfur cathode conversion from elemental sulfur to lithium sulfide (Li 2 S) during discharge follows the solid–liquid–solid reaction mechanism and relies on soluble lithium polysulfide (LiPS) intermediates. − The LiPSs avoid the enormous reaction barrier of direct solid–solid conversion between elemental sulfur and Li 2 S and guarantee smooth energy delivery of Li–S batteries. − Besides, the LiPS-contained electrolyte is able to regulate the phase transition processes regarding dissolution and deposition of elemental sulfur and Li 2 S through chemical disproportionation and comproportionation reactions, which further facilitates the cathode kinetics. − Therefore, the kinetics of LiPSs and their effective regulation largely determine the performances of Li–S batteries.…”