Dengyun Zhai

Mesoporous Cr2O3 nanotubes as an efficient catalyst for Li–O2 batteries with low charge potential and enhanced cyclic performance

Hexagonal close packed Cr2O3, fabricated by an electrospinning technique combined with a heating method, is adopted for the first time as a catalyst for non-aqueous lithium–oxygen (Li–O2) batteries. The synthesized highly mesoporous Cr2O3 nanotubes (Cr2O3-MNT) with a large surface area of 53.4 m2 g−1 are confirmed by field emission scanning electron microscopy (FESEM), field emission high-resolution transmission electron microscopy (TEM) and nitrogen adsorption/desorption isotherms (BET). By using the prepared Super P (SP) (60 wt%)/Cr2O3 (30 wt%)/polyvinylidenefluoride (PVDF) (10 wt%) composite as an oxygen electrode, the Li–O2 battery shows an astonishingly enhanced capacity of 8280 mA h g−1 at a current density of 50 mA g−1. More encouragingly, when the current densities are fixed at 25, 50, 100 and 200 mA g−1 with a limited capacity of 500 mA h g−1, the charging potentials are 3.47, 3.51, 3.78 and 4.01 V, respectively, which are among the lowest charge potentials reported to date. By using a capacity-controlled method (1000 mA h g−1) at a current density of 100 mA g−1, the cell shows excellent cyclic stability up to 50 cycles. The reversible formation and dissociation of Li2O2 are verified by X-ray diffusion (XRD) and SEM, indicating that the as-prepared Cr2O3 nanotubes are a promising catalyst for Li–O2 batteries.

Room-temperature liquid metal-based anodes for high-energy potassium-based electrochemical devices

A liquid Na-K alloy is adsorbed onto a super-aligned carbon nanotube membrane (denoted CM) at room temperature, which is driven by capillary force, fabricating a flexible CM@NaK membrane. The anode directly using the CM@NaK membrane exhibits a smooth electrode-electrolyte (liquid-liquid) interface, contributing to fast ion transport and a dendrite-free stripping/plating process.