The Design of the Ni3N/Nb4N5 Heterostructure as Bifunctional Adsorption/Electrocatalytic Materials for Lithium–Sulfur Batteries

TL;DR

This paper introduces a new material that improves the performance of lithium-sulfur batteries by better handling sulfur compounds and boosting cycle life.

Contribution

The novel Ni3N/Nb4N5 heterostructure is proposed as a bifunctional material for adsorption and electrocatalysis in Li-S batteries.

Findings

The Ni3N/Nb4N5 heterostructure effectively mitigates lithium polysulfide shuttling through strong adsorption.

The material accelerates Li2S nucleation and deposition kinetics, enhancing battery performance.

Li-S cells with the heterostructure separator showed a low capacity decay rate of 0.25% per cycle after 150 cycles.

Abstract

Lithium–sulfur (Li-S) batteries are hindered by the sluggish electrochemical kinetics and poor reversibility of lithium polysulfides (LiPSs), which limits their practical energy density and cycle life. In order to address this issue, a novel Ni3N/Nb4N5 heterostructure was synthesized via electrospinning and nitridation as a functional coating for polypropylene (PP) separators. Adsorption experiments were conducted in order to ascertain the heterostructure’s superior affinity for LiPSs, thereby effectively mitigating their shuttling. Studies of Li2S nucleation demonstrated the catalytic role of the substance in accelerating the deposition kinetics of Li2S. Consequently, Li-S cells that employed the Ni3N/Nb4N5-modified separator were found to achieve significantly enhanced electrochemical performance, with the cells delivering an initial discharge capacity of 1294.4 mAh g−1 at 0.2 C. The results demonstrate that, after 150 cycles, the cells retained a discharge capacity of 796.2 mAh g−1, corresponding to a low capacity decay rate of only 0.25% per cycle. In addition, the rate capability of the cells was found to be improved in comparison to control cells with NiNb2O6-modified or pristine separators.

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