title: Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium-Oxygen Batteries.
abstract: Lithium-oxygen (Li-O2) batteries have an extremely high theoretical specific energy density when compared with conventional energy-storage systems. However, practical application of the Li-O2 battery system still faces significant challenges. In this work, we report a new approach for synthesis of ultrafine metal oxide nanocatalysts through an electrochemical prelithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20-30 nm to a uniformly distributed domain of ∼2 nm and significantly improves their catalytic activity. Structurally, the prelithiated NCO nanowires feature ultrafine NiO/CoO nanoparticles that are highly stable during prolonged cycles in terms of morphology and particle size, thus maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. A Li-O2 battery using this catalyst demonstrated an initial capacity of 29 280 mAh g(-1) and retained a capacity of >1000 mAh g(-1) after 100 cycles based on the weight of the NCO active material. Direct in situ transmission electron microscopy observations conclusively revealed the lithiation/delithiation process of as-prepared NCO nanowires and provided in-depth understanding for both catalyst and battery chemistries of transition-metal oxides. This unique electrochemical approach could also be used to form ultrafine nanoparticles of a broad range of materials for catalyst and other applications.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Pengfei
authors.initials: P
authors.lastname: Yan
authors.forename: Wu
authors.initials: W
authors.lastname: Xu
authors.forename: Jianming
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Mechanical Engineering and Materials Science, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
authors.forename: Yang
authors.initials: Y
authors.lastname: He
authors.forename: Langli
authors.initials: L
authors.lastname: Luo
authors.forename: Mark E
authors.initials: ME
authors.lastname: Bowden
authors.forename: Chong-Min
authors.initials: CM
authors.lastname: Wang
authors.forename: Ji-Guang
authors.initials: JG
authors.lastname: Zhang
keywords: Lithium−oxygen battery; NiCo2O4; nanoparticle; prelithiation; ultrafine catalyst