Lotus Root-Like Nitrogen-Doped Carbon Nanofiber Structure Assembled with VN Catalysts as a Multifunctional Host for Superior Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries (LSBs) are regarded as one of the most promising energy-recycling storage systems due to their high energy density (up to 2600 Wh kg−1), high theoretical specific capacity (as much as 1672 mAh g−1), environmental friendliness, and low cost. Originating from the complicated redox of lithium polysulfide intermediates, Li–S batteries suffer from several problems, restricting their application and commercialization. Such problems include the shuttle effect of polysulfides (Li2Sx (2 < x ≤ 8)), low electronic conductivity of S/Li2S/Li2S2, and large volumetric expansion of S upon lithiation. In this study, a lotus root-like nitrogen-doped carbon nanofiber (NCNF) structure, assembled with vanadium nitride (VN) catalysts, was fabricated as a 3D freestanding current collector for high performance LSBs. The lotus root-like NCNF structure, which had a multichannel porous nanostructure, was able to provide excellent (ionically/electronically) conductive networks, which promoted ion transport and physical confinement of lithium polysulfides. Further, the structure provided good electrolyte penetration, thereby enhancing the interface contact with active S. VN, with its narrow resolved band gap, showed high electrical conductivity, high catalytic effect and polar chemical adsorption of lithium polysulfides, which is ideal for accelerating the reversible redox kinetics of intermediate polysulfides to improve the utilization of S. Tests showed that the VN-decorated multichannel porous carbon nanofiber structure retained a high specific capacity of 1325 mAh g−1 after 100 cycles at 0.1 C, with a low capacity decay of 0.05% per cycle, and demonstrated excellent rate capability.

Cinnamon-Derived Hierarchically Porous Carbon as an Effective Lithium Polysulfide Reservoir in Lithium–Sulfur Batteries

“…To address these issues, the sulfur cathode design has been reconfigured by embedding sulfur into highly conductive porous carbons [ 8 , 9 , 10 ], encapsulating sulfur using conductive polymer coatings [ 11 , 12 , 13 ], utilizing Li 2 S as an initial active material [ 14 ] and utilizing lithium polysulfide adsorbents to trap the lithium polysulfides within the cathode to enhance the cycling performance of Li–S cells [ 15 , 16 , 17 ]. In addition, strategies such as protecting the lithium metal surface [ 18 , 19 , 20 ], utilizing non-lithium metal anodes [ 21 ], modifying the electrolyte composition through a rational selection of solvents and electrolyte additives [ 22 , 23 ] and modifying the separator to block the migration of lithium polysulfides to the anode side have been adopted to mitigate the capacity-fading observed upon cycling [ 24 , 25 , 26 ].…”

Advanced Nanostructured Materials for Electrocatalysis in Lithium–Sulfur Batteries

“…For efficient Li-S battery electrocatalysts (especially heterogeneous catalysts), in addition to the material properties and catalytic mechanism, reasonable nanostructure and molecular structure are also important parameters that determine the catalytic performance [ 68 ]. However, so far, few reviews have explored the effect of nanostructure and molecular structure on the catalytic performance of electrocatalysts for Li-S batteries.…”

Recent Progress in Quasi/All-Solid-State Electrolytes for Lithium–Sulfur Batteries

“…However, several issues still inhibit the development of Li-S batteries, such as the shuttle effect that dissolution and unwanted crossover between the anode and cathode of long-chain polysulfide, undesirably causing a capacity loss and a reduced roundtrip efficiency (Bonnick et al, 2019). The continued growth of lithium dendrites can easily lead to internal short-circuit and even thermal runaway failure (Wei et al, 2019;. To alleviate the aforementioned issues, numerous strategies have been applied, such as using host matrices (Wang M. et al, 2017) and electrolyte additives (Ding et al, 2020).…”