MoS$_2$ 2D-polymorphs as a Li-/Na-ion batteries: 1T' vs 2H phases

TL;DR

This study compares the electrochemical performance of 1T' and 2H phases of MoS₂ monolayers for Li/Na-ion batteries, revealing phase stability changes, ion diffusion differences, and the superior potential of 1T' for battery applications.

Contribution

It introduces a detailed comparison of 1T' and 2H MoS₂ phases using DFT and molecular dynamics, highlighting the stability and diffusion advantages of the 1T' phase for battery use.

Findings

1T'-MoS₂ becomes more stable than 2H at high ion concentrations.

Ion diffusion is more efficient in 1T'-MoS₂.

1T'-MoS₂ shows higher potential for Li/Na-ion batteries.

Abstract

In this study, we compare the performance of two phases of MoS$_2$ monolayers: 1T' and 2H, about their ability to adsorb lithium and sodium ions. Employing the density functional theory and molecular dynamics, we include the ion concentration to analyze the electronic structure, ion kinetics, and battery performance. The pristine 2H-MoS$_2$ monolayer is the ground state. However, the charge transfer effects above a critical ion concentration yields a stability change, where the 1T'-MoS$_2$ monolayer with adsorbed ions becomes more stable than the 2H counterpart. The diffusion of ions onto the 1T' monolayer is anisotropic, being more efficient at ion adsorption than the 2H phase. Finally, we calculate the open circuit voltage and specific capacity, confirming that the 1T'-MoS$_2$ phase has great potential for developing lithium/sodium ion batteries.