Won Jin Kwak

The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO2 emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal–air batteries have th

Improved efficiency and cyclability of cells containing LiBr demonstrate that the appropriate choice of electrolyte solution is the key to a successful Li–O₂ battery.

Although lithium-oxygen batteries are attracting considerable attention because of the potential for an extremely high energy density, their practical use has been restricted owing to a low energy efficiency and poor cycle life compared to lithium-ion batteries. Here we present a nanostructured cathode based on molybdenum carbide nanoparticles (Mo2C) dispersed on carbon nanotubes, which dramatically increase the electrical efficiency up to 88% with a cycle life of more than 100 cycles. We found

This work deals with core issues of Li–oxygen battery systems; intrinsic stability of polyether electrolyte solutions and the role of important redox mediators such as LiI/I₂.

Non-aqueous lithium-oxygen batteries cycle by forming lithium peroxide during discharge and oxidizing it during recharge. The significant problem of oxidizing the solid insulating lithium peroxide can greatly be facilitated by incorporating redox mediators that shuttle electron-holes between the porous substrate and lithium peroxide. Redox mediator stability is thus key for energy efficiency, reversibility, and cycle life. However, the gradual deactivation of redox mediators during repeated cycl

For resolving the low-energy efficiency issue of Li-O-2 batteries, many kinds of redox mediators (RMs) have been adapted. However, studies looking into the problems of RMs in these systems are insufficient. We compare herein effects and problems of RMs in Li-O-2 batteries by applying unique methodology, based on two types of cells, comparison between argon and oxygen atmospheres and combining electrochemistry in conjunction with spectroscopy. Using systematic electrochemical measurements, repres

NCL is rationally designed as the stable protective layer on Li metal for dendrite- and oxygen-proof in Li–O₂ batteries.

Abstract Lithium–oxygen batteries are in fact the only rechargeable batteries that can rival internal combustion engines, in terms of high energy density. However, they are still under development due to low‐efficiency and short lifetime issues. There are problems of side reactions on the cathode side, high reactivity of the Li anode with solution species, and consumption of redox mediators via reactions with metallic lithium. Therefore, efforts are made to protect/block the lithium metal anode

Lithium–oxygen (Li–O2) batteries with high reversibility require a stable electrolyte against the side reactions with Li-metal anode and reactive oxygen species. Moreover, an electrolyte that can effectively utilize the low partial pressure of oxygen in the atmosphere has significant effect on the practical application of Li–air batteries. In this study, a localized high-concentration electrolyte (LHCE) was developed using 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether (OTE) as a dilue

Abstract A stable electrolyte is critical for practical application of lithium–oxygen batteries (LOBs). Although the ionic conductivity and electrochemical stability of the electrolytes have been extensively investigated before, their oxygen solubility, viscosity, volatility, and the stability against singlet oxygen ( 1 O 2 ) still need to be comprehensively investigated to provide a full picture of the electrolytes, especially for an open system such as LOBs. Herein, a systematic investigation

ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTControversial Topics on Lithium Superoxide in Li–O2 BatteriesWon-Jin Kwak†, Jin-Bum Park†, Hun-Gi Jung‡, and Yang-Kook Sun*†View Author Information† Department of Energy Engineering, Hanyang University, Seoul 133-791, Republic of Korea‡ Center for Energy Convergence Research, Green City Technology Institute, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea*E-mail: [email protected]. Tel: +82-2-2220-0524. Fax: +81-2-2292-732

FeCo bimetal decorated CNTs were synthesized as highly efficient and cost-effective non-noble metal catalysts for Li-O₂batteries.

Li–O2 batteries are plagued by side reactions that cause poor rechargeability and efficiency. These reactions were recently revealed to be predominantly caused by singlet oxygen, which can be neutralized by chemical traps or physical quenchers. However, traps are irreversibly consumed and thus only active for a limited time, and so far identified quenchers lack oxidative stability to be suitable for typically required recharge potentials. Thus, reducing the charge potential within the stability

Employing organic redox mediators (ORMs) for lithium–oxygen (Li–O2) batteries has emerged as an important strategy to suppress charging overpotentials. Judicious molecular designs of ORMs can also tailor their redox potential and electron-transfer rate to optimize the catalytic efficiency. However, the stability of ORMs in Li–O2 cells was scarcely studied. Here, the catalytic efficiency and stability of several important ORMs are assessed through in situ gas analysis and reactivity tests with si