Hexagonal boron nitride with vacancy engineering as an efficient polysulfide anchor and electrocatalyst for Na-S...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Sodium-sulfur (Na-S) batteries offer high energy density and low cost.
• Key challenges include capacity loss due to sodium polysulfide (NaPs) dissolution and slow reaction kinetics.
• Current host materials struggle to effectively anchor NaPs and facilitate electrochemical conversion.

Purpose of the Study:

• To investigate the impact of vacancy-induced modifications in hexagonal boron nitride (h-BN) on Na-S battery performance.
• To enhance the catalytic activity and sulfur species anchoring capabilities of h-BN.
• To understand the electronic and structural changes in h-BN upon vacancy creation.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to analyze interactions between h-BN and NaPs.
• The study systematically introduced single and double vacancies (nitrogen and boron) in the h-BN lattice.
• Density of State (DOS) calculations were performed to assess changes in electrical properties.

Main Results:

• Pristine h-BN shows weak interaction with NaPs; vacancy introduction significantly strengthens this interaction.
• Double nitrogen or boron vacancies provide the strongest binding, effectively suppressing the polysulfide shuttle.
• Vacancy-engineered h-BN exhibits enhanced electronic properties, transitioning from insulating to semiconducting/semimetallic behavior.
• Polysulfides bind more strongly to vacancy-engineered h-BN than electrolyte molecules.

Conclusions:

• Vacancy-engineered h-BN serves as an effective host material for Na-S batteries.
• The enhanced affinity for NaPs and improved electronic properties mitigate the shuttle effect and capacity fade.
• This approach offers a promising strategy for developing advanced Na-S battery technologies.