Constructing Binder‐ and Carbon Additive‐Free Organosulfur Cathodes Based on Conducting Thiol‐Polymers through Electropolymerization for Lithium‐Sulfur Batteries

Abstract

Herein, the concept of constructing binder-and carbon additive-free organosulfur cathode was proved based on thiolcontaining conducting polymer poly(4-(thiophene-3-yl) benzenethiol) (PTBT). The PTBT featured the polythiophene-structure main chain as a highly conducting framework and the benzenethiol side chain to copolymerize with sulfur and form a crosslinked organosulfur polymer (namely S/PTBT). Meanwhile, it could be in-situ deposited on the current collector by electropolymerization, making it a binder-free and free-standing cathode for Li-S batteries. The S/PTBT cathode exhibited a reversible capacity of around 870 mAh g À 1 at 0.1 C and improved cycling performance compared to the physically mixed cathode (namely S&PTBT). This multifunction cathode eliminated the influence of the additives (carbon/binder), making it suitable to be applied as a model electrode for operando analysis. Operando X-ray imaging revealed the remarkable effect in the suppression of polysulfides shuttle via introducing covalent bonds, paving the way for the study of the intrinsic mechanisms in Li-S batteries.

How regiochemistry influences aggregation behavior and charge transport in conjugated organosulfur polymer cathodes for lithium-sulfur batteries

“…In particular, the focus has been set on the PTBT polymer, which has been extensively studied as an alternative cathode material. 21,24 By using classical molecular dynamics, for which we re-parametrized important force field parameters based on density functional theory calculations, we simulate the self-assembled aggregation of polymer chains with different regioregularity. We find that the polymer chains can form crystalline phases only for a regioregular head-to-tail/head-to-tail (HT-HT) regularity, whereas, for a head-to-head/tail-to-tail (HH-TT) regularity, the system does not show any long-range order after annealing.…”

“…With prolonged electro-polymerization time, the PTBT film becomes thicker and looser, from which the outer layer is likely to fall off. 21 The detached tances of similar polythiophene-based polymers. [59][60][61] The simulated spectrum also features a distinct peak at 2Θ = 23.9 • , corresponding to the stacking of thiophene backbones along the short a-axis.…”

“…[12][13][14][15][16][17][18] Among these, thiol-containing polymers are one example where the -SH groups can be cross-linked with sulfur via covalent bonding. [19][20][21] In a recent study, we presented a new fabrication strategy to construct a binder-and carbon additive-free organosulfur cathode based on a thiol-containing conducting polymer poly(4-(thiophene-3-yl)benzenethiol) (PTBT). 21 The PTBT features the polythiophene main chain as a highly conducting framework and the benzenethiol side chain to copolymerize 22,23 with sulfur and form a cross-linked organosulfur polymer.…”

“…[19][20][21] In a recent study, we presented a new fabrication strategy to construct a binder-and carbon additive-free organosulfur cathode based on a thiol-containing conducting polymer poly(4-(thiophene-3-yl)benzenethiol) (PTBT). 21 The PTBT features the polythiophene main chain as a highly conducting framework and the benzenethiol side chain to copolymerize 22,23 with sulfur and form a cross-linked organosulfur polymer. We have been able to show the significant fixing effect of sulfur species by operando X-ray imaging.…”

Solvation structure of conjugated organosulfur polymers for lithium-sulfur battery cathodes

“…The PTBT polymer is a flexible, conjugated, carbon additive-free cathode for Li/S batteries. 32 The thiophene ring in TBT acts as the conjugated backbone, while benzenethiol is the organosulfur-based side chain. In recent work, we showed that out of different regio-regularities of thiophene groups, a head-to-tail/head-to-tail regularity leads to a crystalline phase while a head-to-head/tail-to-tail regularity shows no long-range order.…”