Improved Na-ion kinetics of 1T MoS2 nanopatterned porous hard carbon as an ultra-long life anode

Abstract

Porous hard carbons (PHC) are promising anode materials in sodium-ion batteries; however, the availability of large surface area creates numerous irreversible active sites that cause rapid initial cycle capacity fading and electrode degradation, resulting in lower specific capacity and poor cycle stability. PHC surface modification via 2D transition metal dichalcogenides is a synergistic approach to combine excellent electrochemical properties of both materials and resolve these issues. Therefore, we designed 1T MoS2 nanopatterned PHC skeleton using carbonization and hydrothermal treatment of biomass (chickpea husk). As a result, HC@MoS2-II electrode with extended d002 spacing of MoS2 nanolayers (0.650 nm) exhibited an excellent specific capacity of 470 mAh/g at 50 mA/g with high initial coulombic efficiency (63%) and ultra-long cycle stability (190 mAh/g) at 1000 mA/g over 3500 cycles. The extraordinary electrochemical performance can be attributed to the synergistic assembly, where the high surface area PHC skeleton effectively buffered large volume expansion during charging/discharging, and 1T MoS2 nanoflowers added fast ionic diffusion kinetics and PHC surface protection.