Enhancement of Functionalized 1T-NbS2 Monolayer Properties for the Superior Anode of Na-Ion Batteries

Abstract

One of the most important factors influencing the performance of Na-ion batteries (NIBs) is the anode’s quality. Currently, NIB anodes have numerous disadvantages, including low capacity, rapid volume change, temperature variable conductivity and poor thermal/chemical stability. In this work, the electronic and transport properties of undoped, doped and defective 1T-NbS<inf>2</inf> monolayers were investigated using density functional theory calculations. The maximum quantum capacitance of 1T-NbS<inf>2</inf> with S-vacancy (V<inf>S</inf>-NbS<inf>2</inf>) changes from 20.49 to 16.92 ?F/cm2 across temperature ranges of 200 K to 1000 K, indicating its suitability as anode with temperature-stable capacity. The 1T-NbS<inf>2</inf> monolayers exhibit high electrical conductivity with less than 6% fluctuation across a temperature range of 200 K to 1000 K, indicating thermally stable conductance. The 1T-NbS<inf>2</inf> layered structure has substantially larger interlayer spacing of 0.615 nm than the size of Na ion (0.095 nm), as well as a relatively tiny variation (0.05 eV for V<inf>S</inf>-NbS<inf>2</inf>) in cohesive energies between sodiated and de-sodiated phases, making it a good choice for anodes. For V<inf>S</inf>-NbS<inf>2</inf>, the seebeck coefficient ranges from -5 to -40 ?V/K, which is often obtained by the most commonly used Na-metal anode, demonstrating its appropriateness as anode. According to our findings, 1T-NbS<inf>2</inf> is a great option for thermally stable NIB electrode applications. © 2002-2012 IEEE.