Metal-N4@Graphene as Multifunctional Anchoring Materials for Na-S Batteries: First-Principles Study

Abstract

Developing highly efficient anchoring materials to suppress sodium polysulfides (NaPSs) shuttling is vital for the practical applications of sodium sulfur (Na-S) batteries. Herein, we systematically investigated pristine graphene and metal-N4@graphene (metal = Fe, Co, and Mn) as host materials for sulfur cathode to adsorb NaPSs via first-principles theory calculations. The computing results reveal that Fe-N4@graphene is a fairly promising anchoring material, in which the formed chemical bonds of Fe-S and N-Na ensure the stable adsorption of NaPSs. Furthermore, the doped transition metal iron could not only dramatically enhance the electronic conductivity and the adsorption strength of soluble NaPSs, but also significantly lower the decomposition energies of Na2S and Na2S2 on the surface of Fe-N4@graphene, which could effectively promote the full discharge of Na-S batteries. Our research provides a deep insight into the mechanism of anchoring and electrocatalytic effect of Fe-N4@graphene in sulfur cathode, which would be beneficial for the development of high-performance Na-S batteries.

Two-dimensional titanium carbide (Ti3C2Tx) MXenes to inhibit the shuttle effect in sodium sulfur batteries

“…Thus, this material is suitable for both suppressing the shuttle effect and catalyzing the electrochemistry process. Note that the obtained barriers are comparable to the values of the 2D materials such as chromium nitrogen-doped graphene (Cr@NG) 1.54 eV, 22 pristine graphene 1.94 eV, Fe–N4@graphene 1.05 eV, 23 and single-layer vanadium disulfide (VS 2 ) 0.53 eV. 44…”

“…18–20 In particular, polar surfaces of some 2D materials play a facilitating role in maximizing binding energies with Na 2 S n . The polar surfaces of nitrogenated holey graphene (C 2 N), 21 single-atom catalysts (SACs) on nitrogen-doped graphene, 22 metal-N4@graphene, 23 and nickel sulfide nanocrystals on nitrogen-doped carbon nanotubes 24 exemplify the enhancements in binding energies of these 2D materials with Na 2 S n . Furthermore, recent studies demonstrate that sulfur-doped Ti 3 C 2 T x MXenes can improve the electrochemical performance of sulfur electrode due to the high surface polarity that strengthens the binding energies with sodium polysulfides.…”

A Review on the Construction of Carbon-Based Metal Compound Composite Cathode Materials for Room Temperature Sodium-Sulfur Batteries

“…Overall, the reason why it is difficult to achieve high utilization of S cathode is not only related to the dissolution of intermediate products due to contact with the electrolyte, but also related to its own structural characteristics and reaction mechanism. Therefore, according to the current relatively novel research reports, to improve the cycle stability of cathode materials, the cathode composite materials for RT Na-S batteries can be constructed based on both adsorption and electrocatalysis ( Yang, et al, 2021b ; Yang, et al, 2021c ). This paper summarizes the main factors that lead to the instability of cathode materials for RT Na-S batteries, and introduces long-term effective optimization strategies for cathode materials.…”

Software for Evaluating Long-Range Electrostatic Interactions Based on the Ewald Summation and Its Application to Electrochemical Energy Storage Materials

“…Ordered mobile ion/vacancy arrangements on the atomic scale have great impact on the open circuit voltage, ionic conductivity, and other characteristics of electrochemical energy storage materials. However, it is often challenging to accurately locate light elements such as Li or Na in a crystal structure with commonly used X-ray diffraction and the secondary battery is also easily affected by kinetics during the working process. − As a result, it may be fruitful to apply theoretical methods to predict ordered phases of the ground state. Theoretical prediction of ordered phases is usually based on the lattice-gas model.…”