Ultrastable Sodium–Sulfur Batteries without Polysulfides Formation Using Slit Ultramicropore Carbon Carrier

Abstract

The formation of the soluble polysulfides (Na2Sn, 4 ≤ n ≤ 8) causes poor cycling performance for room temperature sodium–sulfur (RT Na–S) batteries. Moreover, the formation of insoluble polysulfides (Na2Sn, 2 ≤ n < 4) can slow down the reaction kinetics and terminate the discharge reaction before it reaches the final product. In this work, coffee residue derived activated ultramicroporous coffee carbon (ACC) material loading with small sulfur molecules (S2–4) as cathode material for RT Na–S batteries is reported. The first principle calculations indicate the space confinement of the slit ultramicropores can effectively suppress the formation of polysulfides (Na2Sn, 2 ≤ n ≤ 8). Combining with in situ UV/vis spectroscopy measurements, one‐step reaction RT Na–S batteries with Na2S as the only and final discharge product without polysulfides formation are demonstrated. As a result, the ultramicroporous carbon loaded with 40 wt% sulfur delivers a high reversible specific capacity of 1492 mAh g−1 at 0.1 C (1 C = 1675 mA g−1). When cycled at 1 C rate, the carbon–sulfur composite electrode exhibits almost no capacity fading after 2000 cycles with 100% coulombic efficiency, revealing excellent cycling stability and reversibility. The superb cycling stability and rate performance demonstrate ultramicropore confinement can be an effective strategy to develop high performance cathode for RT Na–S batteries.

Research Progress toward Room Temperature Sodium Sulfur Batteries: A Review

“…Recently, Guo et al [ 60 ] produced a porous material with ultramicropores as the main body. The material is obtained by carbonizing and activating coffee grounds.…”

“…In addition to the above-mentioned sulfur hosts, porous carbon nanotubes are also a multifunctional sulfur host. In order to solve the problem of rapid capacity decay and low reversible capacity of room temperature sodium–sulfur batteries, researchers at the University of Wollongong in Australia have developed a nanomaterial with nickel sulfide nanocrystals implanted in nitrogen-doped porous carbon nanotubes for sodium-sulfur batteries cathode [ 60 ]. The material is not only superior in performance, but also suitable for mass production and commercialization.…”

Prelithiation/Presodiation Techniques for Advanced Electrochemical Energy Storage Systems: Concepts, Applications, and Perspectives

“…Addressing the safety issues in Li/Na-S and Li/Na-O 2 batteries. [55][56][57][58][59] At present, Li/Na-S batteries are typically consisted of a Li/Na metal anode and an S cathode, and the Li/Na-O 2 batteries possess O 2 as the active material coupled with the Li/Na metal anode. The concerned safety issues are mainly resulted from the usage of highly active Li/Na metal.…”

Recent Advances in Emerging Non‐Lithium Metal–Sulfur Batteries: A Review

“…In addition to the commercial porous carbon materials, [73,74] other porous carbon matrices prepared through the template method, [75][76][77][78][79] direct carbonization of biomass and organic complexes, [80][81][82][83][84] and wet-chemical synthesis approaches [85] have also been employed as sulfur hosts for RT Na-S batteries. Chou et al constructed an elaborately designed carbon framework, called interconnected mesoporous hollow carbon nanosphere, as a sulfur host for RT Na-S batteries (Figure 6a).…”