Effect of lithium-trapping on nitrogen-doped graphene as an anchoring material for lithium–sulfur batteries: a density functional theory study

Abstract

N-Doped graphene (NG) has been widely used as a cathode material for lithium-sulfur (Li-S) batteries due to its strong interaction with lithium polysulfide (LiPS) species. However, strong interaction between the NG substrate and the LiPS molecules induces undesirable molecular structure decomposition of LiPS. Due to the strong interaction between Li and NG, Li-trapping occurs during battery operation. Therefore, in this study, Li-trapped NG (LiNG) is introduced as a possible structure of NG, and the structural stability of LiNG under applied electric potential is examined. The effect of Li-trapping on the properties of NG as an anchoring material for Li-S batteries is investigated using density functional theory calculations. Li-trapping relieves the strong interaction between NG and LiPS, thereby avoiding decomposition of the LiPS molecule. Although the interaction between the LiPS molecule and the substrate is weakened, additionally formed interaction after Li-trapping, which is between Li in the substrate and S in the molecule, enables LiNG to suppress the shuttle effect. LiNG shows advanced anchoring behavior that suppresses the shuttle effect without any molecular decomposition of LiPS. This finding provides a further understanding of the effect of Li-trapping on the anchoring properties of NG for Li-S batteries.

Trapping polysulfide on two-dimensional molybdenum disulfide for Li–S batteries through phase selection with optimized binding

“…Both 2H-MoS 2 and 1T'-MoS 2 monolayers show less trapping of S 8 with a binding energy of 0.04 eV. The binding energies of Li 2 S x on borophene are in the range from −1.00 to −3.00 eV [15] and on Ni-doped graphene are in the range from 1.13 to 1.40 eV [11]. The 1T'-MoS 2 monolayer can be used as a conductive anchoring material to design advanced Li–S batteries.…”

“…However, the adsorption of polarized LPSs on non-polarized graphene is weak; heteroatom doping is necessary for improving the anchoring effect. Nitrogen doping has been used to modify the anchoring behavior of graphene, and the N-doped graphene showed improved anchoring of Li 2 S x [11]. Polar materials were explored to trap LPSs, such as metal oxide [12–13] and metal-carbide nanoparticles [14].…”

Improved Performance and Immobilizing Mechanism of N‐doping Carbon Aerogel with Net Channel via Long‐Chain Directing for Lithium–Sulfur Battery

“…The adsorption energy of HR, formed by the reaction of R and F under the condition of weak acid, to the amide group in PI can be calculated as follows where E PI , E HR , and E PI+HR are the DFT energies of PI unit, single HR molecule, and the whole adsorption system, respectively.…”

“…[40] The adsorption energy of HR, formed by the reaction of R and F under the condition of weak acid, to the amide group in PI can be calculated as follows. [41]…”

The role of functional materials to produce high areal capacity lithium sulfur battery

“…4 (b)). Co-doping graphene such as N, S doped graphene and Si, S doped graphene provides other promising routes to bind PS [71][72][73] . N doped mesoporous carbon (NMPC) was studied by Song et al [74] .…”