Ultra‐Stable Cycling of High Capacity Room Temperature Sodium‐Sulfur Batteries Based on Sulfurated Poly(acrylonitrile)

Abstract

We report on a room temperature (RT) sodium‐sulfur (Na−S) battery based on a sodium anode, a sulfurated poly(acrylonitrile) (SPAN) cathode and an electrolyte containing sodium tetrakis(hexafluoroisopropyloxy) borate (Na[B(hfip)4]; hfip=hexafluoroisopropoxide) in a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC). The hfip anion as a weakly coordinating anion (WCA) provides high anodic stability, high ionic conductivity, and superior electrochemical performance in carbonate‐based solvents. The Na‐SPAN cell exhibits an initial discharge capacity of 1360 normalmnormalAnormalh4ptnormalgnormals-1 and a remarkable reversible capacity of 1072 normalmnormalAnormalh4ptnormalgnormals-1 after 1000 cycles at 3 C (C=C‐rate, 5.025 normalA4ptnormalgnormals-1 ) with an insignificant average capacity decay of less than 0.021 % per cycle. A careful choice of the discharge cut‐off potential (DCP) reveals that a DCP of 0.2 V allows for stable cycling for more than 500 cycles while a DCP of 0.5 V results in a constant capacity decay. The excellent cycle stability at a DCP of 0.2 V is likely to be caused by the high conversion of the SPAN‐bound sulfur into Na2S.

Sulfurized Polypropylene as Low‐Cost Cathode Material for High‐Capacity Lithium‐Sulfur Batteries

“…As mentioned above, the kinetic of this cell is partially controlled by diffusion. More Li 2 S 2 /Li 2 S formation blocks the ion diffusion, therefore the diffusion coefficient of cutoff voltage at 0.45 is lower, whereas the discharge capacity of cutoff voltage at 0.45 is much higher than cutoff voltage at 1 V [40] …”

A Review on the Construction of Carbon-Based Metal Compound Composite Cathode Materials for Room Temperature Sodium-Sulfur Batteries

“…At a rate of 1C, the reversible capacity of the cathode remains 300 mAhg −1 after 1,500 cycles, and the Coulombic efficiency is as high as 98% ( Figure 2F ). The above analysis shows that the special pore structure of the carbon-based composite cathode material can inhibit the dissolution of soluble NaPSs through the mechanism of adsorption ( Fan, et al, 2016 ; Jeon, et al, 2020 ; Murugan, et al, 2021 ), thereby providing a longer cycle life of the battery.…”

Stable Cycling of Room‐Temperature Sodium‐Sulfur Batteries Based on an In Situ Crosslinked Gel Polymer Electrolyte

“…Notably, the anodic stability of the GPE electrolyte against Al reported here is the highest for Na batteries published so far. [34][35][36] Since the ion movement in the electrolyte is crucial for the kinetics during the redox reaction, [37] the ionic conductivity of both the LE and the GPE was measured with the help of blocking SS electrodes at various temperatures (Figure 2b). The bulk resistance of both the GPE and LE was extracted from the impedance spectroscopy data in the highfrequency region (Table S2, Supporting Information).…”