Combined first-principles statistical mechanics approach to sulfur structure in organic cathode hosts for polymer based lithium–sulfur (Li–S) batteries

Schütze, Yannik; Silva, Ranielle de Oliveira; Ning, Jiaoyi; Rappich, Jörg; Lü, Yan; Ruiz, Victor G.; Bande, Annika; Dzubiella, Joachim

doi:10.1039/d1cp04550d

Cited by 12 publications

(21 citation statements)

References 72 publications

(80 reference statements)

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“…In a further study, we used a combination of first-principles computational methods and statistical mechanics to explore the structural characteristics of the initial state of a vulcanized PTBT polymer. 24 Our calcu-lations showed that the main reaction of the vulcanization process leads to high-probability states of sulfur chains cross-linking TBT units belonging to different polymer backbones, with a dominant sulfur chain length of 5 atoms. Similar results have been reported for different sulfur/carbon copolymers.…”

Section: Introductionmentioning

confidence: 76%

“…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.…”

Section: Discussionmentioning

confidence: 99%

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

Schütze

Gayen

Pałczynski

et al. 2023

Preprint

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For lithium-sulfur (Li-S) batteries to become competitive, they require high stability and energy density. Organosulfur polymer-based cathodes have recently shown promising performance due to their ability to overcome common limitations of Li-S batteries, such as the insulating nature of sulfur. In this study, we use a multi-scale modeling approach to explore the influence of the regiochemistry of a novel conjugated poly(4-(thiophene-3-yl)benzenethiol) (PTBT) polymer on its aggregation behavior and charge transport. Classical molecular dynamics simulations of the self-assembly of polymer chains with different regioregularity show that a head-to-tail/head-to-tail (HT-HT) regularity can form a well-ordered crystalline phase of planar chains allowing for fast charge transport. Our X-ray diffraction measurements, in conjunction with our predicted crystal structure, confirm the presence of crystalline phases in the electropolymerized PTBT polymer. As a first quantitative approach, we describe the charge transport in the crystalline phase in a band-like regime. Our results give fundamental insights into the interplay between microstructural and electrical properties of conjugated polymer cathode materials, highlighting the effect of polymer chain regioregularity on its charge transport properties.

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Section: Introductionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

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

Schütze

Gayen

Pałczynski

et al. 2023

Preprint

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“…Finally, the chemical‐bonded organosulfur polymer S/PTBT is formed. According to the findings in our recent work, in which we have investigated the initial structure of the cathode using a combination of electronic‐structure theory and statistical mechanics, [17] we have proposed two possible structures for the S/PTBT polymer, named inter‐chain and intra‐chain, which can be generally distinguished by the way in which the polysulfide chains bind to the TBT units. From these two possible structures, our results showed that pentasulfide (p=5) inter‐chain crosslinks are dominant after vulcanization [17] …”

Section: Resultsmentioning

confidence: 99%

“…From these two possible structures, our results showed that pentasulfide (p = 5) inter-chain crosslinks are dominant after vulcanization. [17] The S/PTBT@NF cathodes without carbon additives and binder are directly applied in the Li-S coin cells. To investigate the effect of interaction between sulfur and PTBT on the conductivity of the cathode, the analysis of the electrochemical impedance spectroscopy (EIS) was first evaluated for Li-S batteries.…”

Section: Chemsuschemmentioning

confidence: 99%

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

Ning

Mei

et al. 2022

ChemSusChem

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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.

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“…The structure of PTBT and vulcanized PTBT, known as S/PTBT, 32 (see Fig. 1) has been investigated both theoretically 34 and experimentally. 32 It has been found that the S/PTBT cathode exhibits a reversible capacity of around 870 mAhg −1 at 0.1C (C-rate: the speed at which a battery is fully charged or discharged), and cycling performance is better than the physical mix of sulfur & PTBT cathode.…”

Section: Introductionmentioning

confidence: 99%

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

Gayen

Schütze

Groh

et al. 2023

Preprint

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Lithium-sulfur (Li/S) batteries constitute a promising, next-generation energy storage technology due to their high theoretical energy density and low cost. To increase sustainability, processability, and battery performance, conducting organic polymers have become a focus of research for the development of better cathode materials. Here, we investigate the solvation structure of the conjugated poly(4-thiophen-3-yl) benzenethiol) (PTBT) polymer as a high-potential macromolecular candidate for cathodes in Li/S batteries. Using molecular dynamics (MD) simulation with newly optimized force-field parameters, we examine the effects of polymer length and various molar fractions of the popular dimethoxyethane (DME) and dioxolane (DOL) solvents on the structure of the PTBT polymer at a temperature of 300 K. We characterize basic polymeric properties as well as the composition-dependent solvent adsorption structure and thermodynamics. Importantly, we find an interesting co-solvency effect, namely that a solvent comprised of about 25% DME and 75% DOL leads to maximum swelling (best solvent quality) behavior, which should be important for optimizing cathode fractality and permeability in applications. Our study thus reveals intriguing polymer-solvent correlations and serves as a first step for further MD studies of realistic polymeric cathode structures and processes, e.g., toward charge transport in vulcanized (S-linked) network topologies.

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Combined first-principles statistical mechanics approach to sulfur structure in organic cathode hosts for polymer based lithium–sulfur (Li–S) batteries

Abstract: A combined DFT–statistical mechanics multi-scale approach unravels the structure of a vulcanized polymer cathode for Li–S batteries and is further supported by Raman spectroscopy. Pentasulfide inter-chain crosslinks are dominant after vulcanization.

Cited by 12 publications

References 72 publications

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

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

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

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

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