Understanding the Effect of Solid Electrocatalysts on Achieving Highly Energy‐Efficient Lithium–Oxygen Batteries

Abstract

Nonaqueous lithium–oxygen (Li–O2) batteries are regarded as a promising electrochemical energy storage technology because of largely defeating commercial Li‐ion batteries on theoretical energy density. However, due to the electrically insulating property of Li2O2, a typical discharge product in Li–O2 batteries, high overpotential is inevitable upon charge. Nonetheless, catalysts could regulate the electrochemical formation pathways of Li2O2, and its morphology is closely bound with the energy required to dissociate. Meanwhile, in addition to Li2O2, alternative discharge products with inherently low dissociation energy can be produced by specific catalysts. Here, fundamental oxygen reduction routes in Li–O2 batteries are focused on, catalyst‐dependent geometry formation of Li2O2 is presented, and geometry‐related charge kinetics are disscussed. Products formed under specific catalysts are further explored with an emphasis on LiO2. Future directions to in situ study the electrocatalytic mechanism are subsequently proposed, and an energy system design based on oxygen redox reactions is conceived to provide new perspectives for future electrochemical energy technologies.

Lithium‐Oxygen Chemistry at Well‐Designed Model Interface Probed by In Situ Spectroscopy Coupled with Theoretical Calculations

“…To tackle the sluggish ORR kinetics, many researchers have focused on the design of solid electrocatalysts. [ 27 ] However, the hunting for electrocatalysts for Li‐O 2 batteries primarily rely on the trial‐and‐error approaches because of an incomplete understanding of the ORR mechanisms in Li‐O 2 batteries so far. Galloway et al.…”

“…To tackle the sluggish ORR kinetics, many researchers have focused on the design of solid electrocatalysts. [27] However, the hunting for electrocatalysts for Li-O 2 batteries primarily rely on the trial-and-error approaches because of an incomplete understanding of the ORR mechanisms in Li-O 2 batteries so far. Galloway et al [28] reported a study of catalysts screening for Li-O 2 batteries, in which the ORR on distinct electrode materials including Au, Pt, Pd, and GC was examined using the shell-isolated nanoparticles for enhanced Raman spectroscopy (SHINERS).…”

Recent Progress of Halide Redox Mediators in Lithium–Oxygen Batteries: Functions, Challenges, and Perspectives

“…Growing concerns over the depletion of fossil fuels and damage to the environment call for clean energy storage technologies like rechargeable batteries. , Li-ion batteries (LIBs) have been the dominant power option in the past 30 years but are restricted by their low energy density (<300 Wh/kg) related to their intercalation chemistry. − Moving from intercalation chemistry to conversion chemistry, lithium–air batteries (LABs), also called lithium–oxygen batteries (LOBs) in the lab stage with pure O 2 as the reactant, have gained much attention owing to their high theoretical energy density (∼3500 Wh/kg), making them promising alternatives to conventional LIBs. − However, currently, several critical issues associated with the Li anode, the electrolyte, and especially the air cathode of LOBs have been puzzling. − As a result of the multi-electron-transfer reactions and the undesirable contact of insulating discharge products deposited on the cathode surface, the kinetics of the electro-oxidation of discharge products are sluggish, leading to large charge overpotentials. − The high potential as well as reactive oxygen intermediates (ROIs) formed during the charge process would incur severe side reactions and further cause poor cyclability and low energy efficiency of the system. ,− …”