A mesoporous tungsten carbide nanostructure as a promising cathode catalyst decreases overpotential in Li–O2 batteries

An innovative approach towards the simultaneous enhancement of the oxygen reduction and evolution reactions using a redox mediator in polymer based Li-O2 batteries

For safety concerns, polymer-based Li-O₂ batteries have received more attention than traditional non-aqueous Li-O₂ batteries. However, poor cycling stability, low round trip efficiency, and over charge potential during cycling are the major shortcomings for their future applications. In this work, a soluble redox mediator integrated into a polymer electrolyte provides immediate access to the solid discharged product, lowering the energy barrier for reversible Li₂O₂ generation and disintegration. Moreover, introducing a redox mediator to the polymer electrolyte boosts the ORR during discharge and the OER during the recharge process. The synergistic redox mediator pBQ (1,4 benzoquinone) dramatically reduces the over-potential. A small proportion of pBQ in the polymer electrolyte allows Li₂O₂ to develop in a thin film-like morphology on the cathode surface, resulting in a high reversible capacity of ∼12 000 mA h g^-1 and an extended cycling stability of 100 cycles at 200 mA g^-1 with a cut-off capacity of 1000 mA h g^-1. The remarkable cell performance is attributed to the fast kinetics of para benzoquinone for the ORR and OER in Li-O₂ batteries. The use of a redox mediator in a polymer electrolyte opens a new avenue for practical Li-O₂ battery applications in achieving low charge potential and excellent energy efficiency.

Critical Advances in Ambient Air Operation of Nonaqueous Rechargeable Li-Air Batteries

Over the past few years, great attention has been given to nonaqueous lithium-air batteries owing to their ultrahigh theoretical energy density when compared with other energy storage systems. Most of the research interest, however, is dedicated to batteries operating in pure or dry oxygen atmospheres, while Li-air batteries that operate in ambient air still face big challenges. The biggest challenges are H₂ O and CO₂ that exist in ambient air, which can not only form byproducts with discharge products (Li₂ O₂ ), but also react with the electrolyte and the Li anode. To this end, recent progress in understanding the chemical and electrochemical reactions of Li-air batteries in ambient air is critical for the development and application of true Li-air batteries. Oxygen-selective membranes, multifunctional catalysts, and electrolyte alternatives for ambient air operational Li-air batteries are presented and discussed comprehensively. In addition, separator modification and Li anode protection are covered. Furthermore, the challenges and directions for the future development of Li-air batteries are presented.

Metal–organic framework derived hollow porous CuO–CuCo2O4 dodecahedrons as a cathode catalyst for Li–O2 batteries

Metal–organic framework derived porous CuO–CuCo₂O₄ dodecahedrons as a cathode catalyst for Li–O₂ batteries with significantly enhanced rate and cyclic performance.