Expediting Stepwise Sulfur Conversion via Spontaneous Built‐In Electric Field and Binary Sulfiphilic Effect of Conductive NbB₂‐MXene Heterostructure in Lithium–Sulfur Batteries

Abstract

Fabricating metal boride heterostructures and deciphering their interface interaction mechanism on accelerating polysulfide conversion at atomic levels are meaningful yet challenging in lithium–sulfur batteries (LSBs). Herein, novel highly‐conductive and binary sulfiphilic NbB2‐MXene heterostructures are elaborately designed with spontaneous built‐in electric field (BIEF) via a simple one‐step borothermal reduction strategy. Experimental and theoretical results reveal that Nb and B atoms can chemically bond with polysulfides, thereby enriching chemical anchor and catalytic active sites. Meanwhile, the spontaneous BIEF induces interfacial charge redistribution to make more electrons transferred to surface NbB2 sites, thereby weakening its strong adsorption property yet accelerating polysulfide transfer and electron diffusion on hetero‐interface, so providing moderate polysulfide adsorb‐ability yet decreasing sulfur‐species conversion energy barriers, further boosting the intrinsically catalytic activity of NbB2‐MXene for accelerated bidirectional sulfur conversion. Thus, S/NbB2‐MXene cathode presents high initial capacity of 1310.1 mAh g−1 at 0.1 C, stable long‐term lifespan with 500 cycles (0.076% capacity decay per cycle) at 1 C, and large areal capacity of 6.5 mAh cm−2 (sulfur loading: 7.0 mg cm−2 in lean electrolyte of 5 µL mgs−1) at 0.1 C. This work clearly unveils the mechanism of interfacial BIEF and binary sulfiphilic effect on accelerating stepwise sulfur conversion at atomic levels.

A Facilely Synthesized NiCo2S4 with Two Mutually Reinforcing Active Sites for High-Performance Lithium–Sulfur Batteries

“…These active sites provide more sites for the adsorption and catalysis of polysulfides, allowing for more efficient redox reactions. − The disordered structures are expected to provide trapping sites for charge carriers and interfere with their rapid recombination to reduce the resistance to charge transfer and improve the electron transfer efficiency. This enhanced charge transfer contributes to the improved redox reaction kinetics of polysulfides. − The element mappings (Figure g) suggest that the distributions of Ni, Co, and S are homogeneously dispersed throughout the structures, which demonstrate that the as-prepared D-NiCo 2 S 4 is beneficial to the absorption and uniform distribution of sulfur.…”

Insight into Accelerating Polysulfides Redox Kinetics by BN@MXene Heterostructure for Li–S Batteries

“…The result shows that BN@MXene works as catalytic during the charge and discharge process. [60] The kinetics of the batteries were greatly improved.…”

Hierarchical carbon hollow nanospheres coupled with ultra-small molybdenum carbide as sulfiphilic sulfur hosts for lithium–sulfur batteries

“…This result indicates that MoC@N-HCS has stronger chemical adsorption ability towards LiPSs, and more Li 2 S 6 is chemically anchored to the surface of the MoC@N-HCS. 37,38 To more deeply study the interaction between the embedded MoC nanoparticles and LiPSs, the samples before and aer the adsorption of Li 2 S 6 were tested by XPS. Fig.…”