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

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.

Nickel Hollow Spheres Concatenated by Nitrogen‐Doped Carbon Fibers for Enhancing Electrochemical Kinetics of Sodium–Sulfur Batteries

“…In summary, a flexible and freestanding S@Ni-NCFs cathode is successfully prepared by electrostatic spinning, subsequent [39][40][41] and the S@Ni-NCFs electrode developed in this work. carbonization, and sulfur-loading process.…”

“…a) Polarization curve and b) EIS of Na 2 S 6 symmetric cells, c) comparison of CV and d) discharge/charge curves of S@Ni‐NCFs and S@NCFs electrodes. e) Schematic diagram of S@Ni‐NCFs about the polysulfide adsorption and conversion processes on the surface of metallic Ni, f) rate contrast between the published literatures and the S@Ni‐NCFs electrode developed in this work.…”

Bifunctional Catalyst for Liquid–Solid Redox Conversion in Room‐Temperature Sodium–Sulfur Batteries

“…To the best of our knowledge, the S/CoS 2 -CoSe 2 @CNFs composite displays a superior rate performance than that of previous reported RT Na-S batteries (Figure 4f ). [7,15,28,[41][42][43][44][45][46][47] Electrochemical impedance spectroscopy (EIS) spectra (Figure S18, Supporting Information) reveal that the S/CoS 2 -CoSe 2 @CNFs possesses lower charge transfer resistance in comparison with that of the S/CoSe 2 @CNFs and S/CoS 2 @CNFs. Furthermore, as shown in Figure 4g, the S/CoS 2 -CoSe 2 @CNFs also achieve the long cycling stability at 1 A g À1 .…”

The Future for Room‐Temperature Sodium–Sulfur Batteries: From Persisting Issues to Promising Solutions and Practical Applications

“…Chen et al prepared a Teflonized carbon matrix doped with electronegative fluorine, which exhibited a strong anchoring effect to suppress the dissolution and accelerate the conversion of polysulfides and achieved a good specific capacity of 800 mAh g −1 at 0.1 C as well as cycling stability for 300 cycles with ≈100% Coulombic efficiency. [100] As compared to single heteroatom doping, codoping of carbon host with two types of heteroatoms has also been achieved. Vogt et al presented a functionalized carbon with a high doping content (≈40 at%) of nitrogen and sulfur from low-cost raw materials.…”