Superior Anchoring of Sodium Polysulfides to the Polar C2N 2D Material: A Potential Electrode Enhancer in Sodium-Sulfur Batteries.

Muhammad Sajjad,Nirpendra Singh,J Andreas Larsson,Tanveer Hussain

doi:10.1021/acs.langmuir.0c02616

Abstract

Despite the high theoretical specific energy in rechargeable sodium–sulfur batteries, the shuttle effect severely hampers its capacity and reversibility, which could be overcome by introducing an anchoring material. We, herein, use first-principles calculations to study the low-cost, easily synthesized, environmentally friendly, and stable two-dimensional polar nitrogenated holey graphene (C2N) and nonpolar polyaniline (C3N) to investigate their performance as anchoring materials and the mechanism behind the binding to identify the best candidate to improve the performance of sodium–sulfur batteries. We gain insight into the interaction, including the lowest-energy configurations, binding energies, binding nature, charge transfer, and electronic properties. Sodium primarily contributes to binding with the nanosheets, which is in accordance with their characteristics as anchoring materials. Sodium polysulfides (NaPSs) and the S8 cluster adsorb at the pores of C2N, where there are six electron lone pairs, one for each N atom. The polar C2N binds the NaPSs much strongly than the nonpolar C3N. In contrast to C3N, the charge population substantially modifies by adsorbing NaPSs on C2N, with a substantial charge transfer from the sulfur atoms. The calculated work function of 6.04 eV for pristine C2N, comparable with the previously reported values, decreases on adsorption of the NaPSs formed from battery discharging. We suggest that the inclusion of C2N into sulfur electrodes could also improve their issue with poor conductivity.

Highlights

The damaging effects of nonrenewable energy, like fossil fuels, on humans and the environment have triggered demands of clean renewable energy resources, which has put stress on the existing green energy storage devices like metal-ion (e.g., Li/ Na-ion) batteries to keep up with the globe’s escalating needs
Li et al used density functional theory (DFT) calculations combined with the van der Waals interaction and solvent models[17,18] to study the anchoring performance of a novel 2D transition metal−organic framework material, hexaaminobenzene-based coordination polymers (HAB-CPs), concerning intermediate dissolution related to lithium polysulfides.[19]
It was found among the studied systems that the vanadium-HAB-CP performed exceptionally well to suppress the shuttle effect in lithium−sulfur batteries

Summary

■ INTRODUCTION

The damaging effects of nonrenewable energy, like fossil fuels, on humans and the environment have triggered demands of clean renewable energy resources, which has put stress on the existing green energy storage devices like metal-ion (e.g., Li/ Na-ion) batteries to keep up with the globe’s escalating needs. Li et al used density functional theory (DFT) calculations combined with the van der Waals (vdW) interaction and solvent models (implicit solvation model and implicit self-consistent electrolyte model)[17,18] to study the anchoring performance of a novel 2D transition metal−organic framework material, hexaaminobenzene-based coordination polymers (HAB-CPs), concerning intermediate dissolution related to lithium polysulfides.[19] It was found among the studied systems that the vanadium-HAB-CP performed exceptionally well to suppress the shuttle effect in lithium−sulfur batteries.

■ RESULTS AND DISCUSSION

■ CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES