Electrocatalytic and stoichiometric reactivity of 2D layered siloxene for high‐energy‐dense lithium–sulfur batteries

Abstract

Lithium-sulfur batteries (LSBs) have emerged as promising power sources for high-performance devices such as electric vehicles. However, the poor energy density of LSBs owing to polysulfide shuttling and passivation has limited their further market penetration. To mitigate this challenge, two-dimensional (2D) siloxene (2DSi), a Si-based analog of graphene, is utilized as an additive for sulfur cathodes. The 2DSi is fabricated on a large scale by simple solvent extraction of calcium disilicide to form a thin-layered structure of Si planes functionalized with vertically aligned hydroxyl groups in the 2DSi. The stoichiometric reaction of 2DSi with polysulfides generates a thiosulfate redox mediator, secures the intercalation pathway, and reveals Lewis acidic sites within the siloxene galleries. The 2DSi utilizes the corresponding in-situ-formed electrocatalyst, the 2D confinement effect of the layered structure, and the surface affinity based on Lewis acid-base interaction to improve the energy density of 2DSi-based LSB cells. Combined with the commercial carbon-based current collector, 2DSi-based LSB cells achieve a volumetric energy density of 612 Wh L cell −1 at 1 mA cm −2 with minor degradation of 0.17% per cycle, which rivals those of state-of-the-art LSBs.This study presents a method for the industrial production of high-energydense LSBs.

Electrocatalyst Modulation toward Bidirectional Sulfur Redox in Li–S Batteries: From Strategic Probing to Mechanistic Understanding

“…The morphologic optimization is regarded as a promising remedy to expose abundant edge sites and thus ameliorate electrocatalytic activity of heterogeneous nanocatalyst. [ 47–51 ] However, their electrocatalytic activity is in essence restricted by the intrinsic electronic structure. In further context, the pristine nanocatalyst can scarcely execute bidirectional redox reactions due to their single active site.…”

Li intercalation in an MoSe2 electrocatalyst: In situ observation and modulation of its precisely controllable phase engineering for a high‐performance flexible Li‐S battery

“…[4][5][6] Since the concept of catalyst was introduced into the lithium-sulfur system, it has been expected to solve the above problems. [7][8][9][10] Recently, lots of efforts have been made to explore excellent cathode materials, such as metal oxides, [11][12][13] sulfides, [14][15][16] nitrides, [17][18][19] and carbides. [20][21][22] Nonetheless, the poor conductivities of the aforementioned polar materials make them need to be combined with abundant carbon materials to speed up the reaction kinetics, 23,24 which in turn brings other problems such as low sulfur content and low volume capacity.…”

Single‐atom electrocatalysts for lithium–sulfur chemistry: Design principle, mechanism, and outlook

“…To date, considerable efforts have been made toward optimization of sulfur and lithium evolution behaviors from various perspectives 8,9 . Accordingly, some favorable progress has been achieved by utilizing various hosts with tailored morphologies, controllable structures, and rich surface chemistries to alleviate the LiPS shuttle effect and propel sulfur redox kinetics 10,11 . Previous studies have demonstrated that the study of sulfur reaction kinetics is the key to breaking through the gap between academic investigations and actual implementation of LSBs.…”