A powerful Li O2 battery based on an efficient hollow Cu2O cathode catalyst with tailored crystal plane

Reacquainting the Sudden-Death and Reaction Routes of Li-O2 Batteries by Ex Situ Observation of Li2O2 Distribution Inside a Highly Ordered Air Electrode

The unclear Li₂O₂ distribution inside an air electrode stems from the difficulty of conducting observation techniques inside a porous electrode. In this work, an integrated air electrode is prepared with highly ordered channels. The morphological composition and distribution of Li₂O₂ inside the real air electrode are clearly observed for the first time. The results show that the toroidal Li₂O₂ is constrained by the channel size and exhibits a larger diameter on the separator side at high currents. In contrast to the reported single-factor experiments, the coupling effects of charge transfer impedance and concentration polarization on sudden death are analyzed in-depth at low and high currents. The growth model suggests that toroidal Li₂O₂ exhibits a high dependence on the electrode surface structure. A new route is proposed in which the Li₂O₂/electrode interface of a toroid is controlled partially by the second single-electron reduction.

Curtailing the Overpotential of Li-CO2 Batteries with Shape-Controlled Cu2 O as Cathode: Effect of Illuminating the Cathode

Li-air batteries are limited to lab-scale research owing to the uninterrupted formation of discharge products. In the case of Li-CO₂ batteries, the increase in overpotential caused by Li₂ CO₃ formation results in cell death. In this study, Cu₂ O crystals having three different types of shapes (i.e., cubic, octahedral, and rhombic) were synthesized to compare their catalytic activity toward CO₂ reactions. The full-cycle and long-term stability test revealed that rhombohedral Cu₂ O facilitates Li₂ CO₃ decomposition more efficiently than that of cubic and octahedral Cu₂ O. The cycle was extended to investigate the photocatalytic activity of the rhombic Cu₂ O by illuminating the cell. The repeated cycles to 1 h showed a maximum overpotential of 1.5 V, which is 0.5 V lower than that of the cell without illumination. A postmortem analysis of the cell after dividing the cycles into segments demonstrated interesting results concerning the role of light and Cu₂ O during the cell cycle.

The design of hollow PdO–Co3O4 nano-dodecahedrons with moderate catalytic activity for Li–O2 batteries

Hollow PdO–Co₃O₄ nano-dodecahedrons can stably cycle for more than 90 cycles with a low overpotential as an electrocatalyst for Li–O₂ batteries.

A Template-Free Microwave Synthesis of One-Dimensional Cu₂O Nanowires with Desired Photocatalytic Property

One-dimensional Cu₂O nanowires were successfully prepared with a template-free microwave synthesis. Neither a surfactant was needed (to induce the growth), nor a long reaction time was required for this method. The structural investigation confirmed the successful preparation of Cu₂O. The morphology images showed that the radial size of the Cu₂O nanowires was 10 nm. The possible growth mechanism was hypothesized according to morphology evolution and references. A series of time-dependent experiments indicated that as time increased, Cu₂O primary particles grew radially into nanowires under microwave energy irradiation. The condition-variable tests revealed that the suitable quantity of NaOH played a vital role in Cu₂O nanowire formation. The photocatalytic property of the sample was investigated by degradation of methyl orange under the irradiation of visible light at room temperature. Benefiting from its unique large surface area, 4 mg of the prepared catalyst degraded 73% of methyl orange (10 mg L⁻¹) in 120 min.