Crystal Surface Engineering Induced Active Hexagonal Co₂ P-V₂ O₃ for Highly Stable Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Controlling crystal planes is key to enhancing nanocatalyst activity.
• Lithium-sulfur batteries (LSBs) show promise for high energy density storage but suffer from polysulfide shuttle effects.

Purpose of the Study:

• To design and synthesize novel nanocrystals with controlled crystal facets for improved LSB performance.
• To investigate the effect of exposing specific crystal planes of cobalt phosphide (Co2P) on the catalytic activity towards lithium polysulfides (LiPSs).

Main Methods:

• Morphological control was used to synthesize hexagonal V2O3 nanosheets loaded with Co2P nanocrystals, exposing the (211) lattice plane (H-Co2P-V2O3).
• The H-Co2P-V2O3 composite was used as a separator modification layer in LSBs.
• Electrochemical performance was evaluated through cycling tests, rate capability measurements, and long-term stability studies.

Main Results:

• The H-Co2P-V2O3 composite significantly boosted LiPSs redox kinetics by increasing Co-active sites and enhancing adsorption/catalysis.
• LSBs with the modified separator exhibited excellent reversibility (876.9 mAh g-1 at 1 C over 500 cycles) and rate capability (611.5 mAh g-1 at 8 C).
• Exceptional long-term cycling stability (0.04% attenuation per cycle over 1000 cycles at 4 C) and high areal capacity (12.38 mAh cm-2 at 14.5 mg cm-2 sulfur loading) were achieved.

Conclusions:

• Crystal surface engineering by exposing the (211) lattice plane of Co2P on V2O3 nanosheets is an effective strategy to improve LSB performance.
• The enhanced catalytic activity towards LiPSs conversion is attributed to the specific crystal facet and composite structure.
• This work provides valuable guidance for developing advanced materials for high-performance lithium-sulfur batteries.