Inverse Vulcanization of a Natural Monoene with Sulfur as Sustainable Electrochemically Active Materials for Lithium-Sulfur Batteries.

Jian Xiao,Fulai Zhao,Wangnian Zhang,Zhicong Liu,Ning Deng,Jijun Liu

doi:10.3390/molecules26227039

Jian Xiao, Fulai Zhao + Show 4 more

Open Access

https://doi.org/10.3390/molecules26227039

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Abstract

A novel soluble copolymer poly(S-MVT) was synthesized using a relatively quick one-pot solvent-free method, inverse vulcanization. Both of the two raw materials are sustainable, i.e., elemental sulfur is a by-product of the petroleum industry and 4-Methyl-5-vinylthiazole (MVT) is a natural monoene compound. The microstructure of poly(S-MVT) was characterized by FT-IR, 1H NMR, XPS spectroscopy, XRD, DSC SEM, and TEM. Test results indicated that the copolymers possess protonated thiazole nitrogen atoms, meso/macroporous structure, and solubility in tetrahydrofuran and chloroform. Moreover, the improved electronic properties of poly(S-MVT) relative to elemental sulfur have also been investigated by density functional theory (DFT) calculations. The copolymers are utilized successfully as the cathode active material in Li-S batteries. Upon employment, the copolymer with 15% MVT content provided good cycling stability at a capacity of ∼514 mA h g−1 (based on the mass of copolymer) and high Coulombic efficiencies (∼100%) over 100 cycles, as well as great rate performance.

Highlights

Sulfur-containing polymers have been paid much more attention by scientists for almost a century due to their invaluable properties such as optical [1,2] and electrical [3]properties, self-healing properties [4], electrochemical properties [5,6,7,8], etc
As a result of the current technical level, there is still a long way to go for Li-S batteries in commercial applications because of some problems, such as sulfur not being conductive, intermediate lithium polysulfide generated during the sulfur cathode electrochemical reaction is dissolved in the electrolyte, and the volume expansion of cathode material happening in the reaction process
As the most basic and most abundant sulfur source, elemental sulfur is stable in thermodynamic stability under normal temperature

Summary

Introduction

Sulfur-containing polymers have been paid much more attention by scientists for almost a century due to their invaluable properties such as optical [1,2] and electrical [3]. As a result of the current technical level, there is still a long way to go for Li-S batteries in commercial applications because of some problems, such as sulfur not being conductive, intermediate lithium polysulfide generated during the sulfur cathode electrochemical reaction is dissolved in the electrolyte, and the volume expansion of cathode material happening in the reaction process. The use of sulfur-containing polymers as cathode materials has been an effective way to solve these problems, because polymers have various molecular structures and definable functional groups, and suitable monomer design enables the target polymer to have good properties such as ionic and electronic conductivity, high sulfur content, suitable viscosity, processability, and controllable morphology These features all contribute to the performance of lithium-sulfur batteries, and the active sulfur is restrained in the polymer chain network through either chemical bonding or physical confinement, which can impede the dissolution of polysulfides in the electrolyte. This provides a new choice for sustainable cathode materials for Li–S batteries

Sample Preparation

Materials Characterization

Measurement of Electrochemical Performances

Results and Discussion

Conclusions