Strong Surface Bonding of Polysulfides by Teflonized Carbon Matrix for Enhanced Performance in Room Temperature Sodium‐Sulfur Battery

Authors: Ajay Piriya Vijaya Kumar Saroja, Kamaraj Muthusamy, and Ramaprabhu Sundara

DOI: doi.org/10.1002/admi.201801873/Adv. Mater. Interfaces 2019, 1801873

Abstract

The practical application of room temperature sodium‐sulfur (Na–S) battery remains far away from the market due to the poor coulombic efficiency and cyclic stability which in turn arises from high dissolution of intermediate polysulfides in carbonate‐based electrolytes, slow reaction kinetics, and low electrical conductivity of sulfur. In this aspect, an advanced cathode structure by incorporating Teflon‐lined conductive carbon substrate (TCS) as a supporting cathode to efficiently immobilize the migration of soluble polysulfides to the anode, as well as enhance the conductivity during the polysulfide conversion, is presented here. After inclusion of TCS, the cell delivers a specific capacity of 800 mAh g⁻¹ at 0.1C (1C = 1672 mA g⁻¹) with 85% enhancement in specific capacity. Also, a stable cyclic stability of about 300 cycles with an excellent capacity retention of about 93% and coulombic efficiency of nearly 100% is obtained. Teflon, which has a linear carbon chain surrounded completely by fluorine atoms, acts as the anchoring sites for trapping the intermediate sodium polysulfides. This study provides a simple approach of controlling the shuttling effect, which can be beneficial for the development of high energy density room temperature Na–S battery.

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