(Digital Presentation) Stable Passivation Layer of Oxygen Deficient α-MoO3-X Nanobelts Suppress Li Dendrites to Achieve High-Capacity Li-S Battery

Abstract

The high energy density lithium metal batteries (LMBs) are considered promising energy storage devices for future development. The Li metal reacts with electrolyte and forms an unstable solid electrolyte interphase (SEI), such SEI break down upon cycles and exposes fresh Li metal to the electrolyte which further initiate the growth of Li dendrites. The Li dendrites eventually penetrate the separator and can cause catastrophic battery failure. To suppress the growth of Li dendrites, we have formed a passivation layer on Li metal anode by using oxygen-deficient α-MoO3 nanobelts (MNBs) via a simple spray coating method. The MNBs were synthesized by simple ball milling method. The porous net-like interconnected structure formed by MNBs accommodates the excess Li, provides shorter diffusion pathways to Li+ ions and avoids the dendritic growth and pulverization of SEI. The Li-Li symmetrical cells with MNBs coated Li electrodes (MNB-Li) operated at current density of 1 mA cm–2 with a deposition capacity of 1 mAh cm–2 shows lower overpotential (~30 mV) than the cells with pristine Li (~45mV) after 100 hours of cycling. Oxygen vacancies present on the surface of MNBs act as shallow donors and boost carrier concentration, resulting in increased surface conductivity. The MNB-Li paired up with sulfur expanded graphite (SEG) cathode and activated expanded graphite (AEG) coated separator offers ~1077 mAh g-1 initial capacity at 0.5C (1C=1600 mAh g-1) and ~99 % coulombic efficiency for 100 cycles. Figure 1