Cobalt‐Doped SnS₂ with Dual Active Centers of Synergistic Absorption‐Catalysis Effect for High‐S Loading Li‐S Batteries

Abstract

The application of Li-S batteries is hindered by low sulfur utilization and rapid capacity decay originating from slow electrochemical kinetics of polysulfide transformation to Li 2 S at the second discharge plateau around 2.1 V and harsh shuttling effects for high-S-loading cathodes. Herein, a cobalt-doped SnS 2 anchored on N-doped carbon nanotube (NCNT@Co-SnS 2 ) substrate is rationally designed as both a polysulfide shield to mitigate the shuttling effects and an electrocatalyst to improve the interconversion kinetics from polysulfides to Li 2 S. As a result, high-S-loading cathodes are demonstrated to achieve good cycling stability with high sulfur utilization. It is shown that Co-doping plays an important role in realizing high initial capacity and good capacity retention for Li-S batteries. The S/NCNT@Co-SnS 2 cell (3 mg cm −2 sulfur loading) delivers a high initial specific capacity of 1337.1 mA h g −1 (excluding the Co-SnS 2 capacity contribution) and 1004.3 mA h g −1 after 100 cycles at a current density of 1.3 mA cm −2 , while the counterpart cell (S/NCNT@SnS 2 ) only shows an initial capacity of 1074.7 and 843 mA h g −1 at the 100th cycle. The synergy effect of polysulfide confinement and catalyzed polysulfide conversion provides an effective strategy in improving the electrochemical performance for high-sulfur-loading Li-S batteries.

Adsorption‐Catalysis Design in the Lithium‐Sulfur Battery

“…[58] Different from metal sulfides, metal nitrides are highly conductive and can be used as an ideal anchoring material. A cobalt-doped SnS 2 QDs anchored on N-doped CNT (NCNT@Co-SnS 2 ) substrate was designed as both a polysulfide shield and an electrocatalyst to enhance the conversion kinetics between LiPSs and Li 2 S, demonstrating an initial capacity of 1337.1 mAh g −1 and remaining at 1004.3 mAh g −1 after 100 cycles at 1.3 mA cm −2 .…”

Highly Stable Lithium−Sulfur Batteries Promised by Siloxene: An Effective Cathode Material to Regulate the Adsorption and Conversion of Polysulfides

“…All peaks of Si/G cathode are sharper and possess stronger peak current density in contrast to those of pure‐G cathode, suggesting better redox reactivity and higher utilization of active S species 52. Meanwhile, comparing the peak potentials (Figure 5b), the Si/G cathode shows significantly higher cathodic reaction potentials and lower anodic reaction potential, which reveals that the introduced siloxene nanosheets can efficiently suppress the electrochemical polarization via accelerated redox kinetics of polysulfides transformation 10,53. Moreover, the cathodic peaks of Si/G cathode show higher onset potentials (Figure 5c) comparing with those of pure‐G cathode, further verifying the better kinetics of polysulfides.…”

“…However, the practical implementation of LSBs, close to commercial application, is plagued with several dilemmas, including insulating nature of sulfur and its final discharge products, highly soluble polysulfides and large volume fluctuation upon lithiation/delithiation process 6–8. Among these intractable issues, dissolved polysulfides in organic electrolytes and their subsequent inter‐electrode migration, namely, shuttling effect, are particularly detrimental to the performances of LSBs, which could lead to rapid capacity attenuation, inefficient sulfur utilization, low coulombic efficiency, and worse still, lithium dendrite issues 9,10. Besides, the sluggish electrochemical conversion kinetics of soluble polysulfides can cause grievous polarization effect, resulting in inferior rate performance 10…”

“…Among these intractable issues, dissolved polysulfides in organic electrolytes and their subsequent inter‐electrode migration, namely, shuttling effect, are particularly detrimental to the performances of LSBs, which could lead to rapid capacity attenuation, inefficient sulfur utilization, low coulombic efficiency, and worse still, lithium dendrite issues 9,10. Besides, the sluggish electrochemical conversion kinetics of soluble polysulfides can cause grievous polarization effect, resulting in inferior rate performance 10…”

Hierarchical Hollow‐Nanocube Ni−Co Skeleton@MoO3/MoS2 Hybrids for Improved‐Performance Lithium‐Ion Batteries

“…[1][2][3][4] Notably,M oS 2 ,w ith al arge surfacea rea and multiple active sites for the deposition of Li ions, is one of the most attractive 2D layered materials.I np articular, MoS 2 has an exceedingly typical SÀMoÀSs andwich structure, in whicht wo sulfur layers sandwichamolybdenum metal layer;t he atoms in the layers are connectedb ys trong covalentb onds, but the layers are bonded by relatively weak van der Waalsf orces. Therefore, it is vital to exploit anodem aterials with excellent electrochemical performancef or the development of LIBs.…”