Achieving High-Performance Room-Temperature Sodium–Sulfur Batteries With S@Interconnected Mesoporous Carbon Hollow Nanospheres

Abstract

Despite the high theoretical capacity of the sodium-sulfur battery, its application is seriously restrained by the challenges due to its low sulfur electroactivity and accelerated shuttle effect, which lead to low accessible capacity and fast decay. Herein, an elaborate carbon framework, interconnected mesoporous hollow carbon nanospheres, is reported as an effective sulfur host to achieve excellent electrochemical performance. Based on in situ synchrotron X-ray diffraction, the mechanism of the room temperature Na/S battery is proposed to be reversible reactions between S and NaS, corresponding to a theoretical capacity of 418 mAh g. The cell is capable of achieving high capacity retention of ∼88.8% over 200 cycles, and superior rate capability with reversible capacity of ∼390 and 127 mAh g at 0.1 and 5 A g, respectively.

Controllable Chain‐Length for Covalent Sulfur–Carbon Materials Enabling Stable and High‐Capacity Sodium Storage

“…[45,46] As the covalent sulfur is increased in C-BDSA, a pair of invertible redox peaks appeared at 0.85/1.96 V from the beginning at the second cycle, which is likely to be attributable to the formation/transformation of Na 2 S via sodiation/desodiation of the chemically bonded S (short-chain). [8,10] It is demonstrated that a stepped redox reactions between S and Na that the covalently bonded S is electrochemically activated to convert into S 2− , which further accommodate Na, thus enhancing the reversible capacity. [8,10] It is demonstrated that a stepped redox reactions between S and Na that the covalently bonded S is electrochemically activated to convert into S 2− , which further accommodate Na, thus enhancing the reversible capacity.…”

“…[8][9][10][11] In the process of cycle, the elemental sulfur of the cathode is dissolvated, reduced to form various soluble polysulfides, that is, S x 2− ions and radicals (1 ≤ x ≤ 8), and eventually the insoluble Na 2 S 2 and Na 2 S. [8,10,12] However, the practical applications are seriously hindered by several obstacles, in which the fundamental challenges are originated from the insulating properties of elemental sulfur and sodium sulfides, the volume changes at the cathode on cycling and the dissolution of sodium poly sulfides in the electrolyte. [8][9][10][11] In the process of cycle, the elemental sulfur of the cathode is dissolvated, reduced to form various soluble polysulfides, that is, S x 2− ions and radicals (1 ≤ x ≤ 8), and eventually the insoluble Na 2 S 2 and Na 2 S. [8,10,12] However, the practical applications are seriously hindered by several obstacles, in which the fundamental challenges are originated from the insulating properties of elemental sulfur and sodium sulfides, the volume changes at the cathode on cycling and the dissolution of sodium poly sulfides in the electrolyte.…”

“…[25][26][27] Instead of relying on polar-polar interactions, the suitably tailored hosts can bind sodium polysulfides through metal-sulfur bonding. [8,10] As a result, the aggregated particles are Room temperature sodium-sulfur batteries have emerged as promising candidate for application in energy storage. [28][29][30][31] In practice, these oxide and sulfide materials are able to bridge sodium polysulfides through both polar-polar Na-S(O) interaction and Lewis acid-base bonding, depending on the exposed facets to some extent.…”

Design and Construction of Sodium Polysulfides Defense System for Room‐Temperature Na–S Battery

“…[10] Finally, sodium polysulfides generated in the multistep reaction have high reactivity and solubility and are easy to diffuse to the sodium anode, resulting in serious "shuttle effect" that leads to a significant reduction in capacity. [22] Although the S/carbon hybrid design can immensely improve the utilization of S, it has to be pointed out that it is difficult to achieve complete electrochemical reversibility because the Room-temperature Na-S batteries are facing one of the most serious challenges of charge/discharge with long cycling stability due to the severe shuttle effect and volume expansion. [14][15][16] For example, porous carbon materials with good electrical conductivity can be combined with S to enhance the electrical conductivity of the cathode, such as carbon nanofiber, [17,18] carbon cloth, [19] carbon nanotube, [20,21] etc.…”

“…[11][12][13] Some progresses have been made in improving the poor conductivity of S and reaction kinetics of room-temperature Na-S batteries. [22] Although the S/carbon hybrid design can immensely improve the utilization of S, it has to be pointed out that it is difficult to achieve complete electrochemical reversibility because the Room-temperature Na-S batteries are facing one of the most serious challenges of charge/discharge with long cycling stability due to the severe shuttle effect and volume expansion. Introducing carbon matrix can not only improve the utilization of S, but also are able to efficiently accommodate the volume expansion due to their abundant porous structure.…”