title: Atomic resolution study of reversible conversion reaction in metal oxide electrodes for lithium-ion battery.
abstract: Electrode materials based on conversion reactions with lithium ions have shown much higher energy density than those based on intercalation reactions. Here, nanocubes of a typical metal oxide (Co3O4) were grown on few-layer graphene, and their electrochemical lithiation and delithiation were investigated at atomic resolution by in situ transmission electron microscopy to reveal the mechanism of the reversible conversion reaction. During lithiation, a lithium-inserted Co3O4 phase and a phase consisting of nanosized Co-Li-O clusters are identified as the intermediate products prior to the subsequent formation of Li2O crystals. In delithiation, the reduced metal nanoparticles form a network and breakdown into even smaller clusters that act as catalysts to prompt reduction of Li2O, and CoO nanoparticles are identified as the product of the deconversion reaction. Such direct real-space, real-time atomic-scale observations shed light on the phenomena and mechanisms in reaction-based electrochemical energy conversion and provide impetus for further development in electrochemical charge storage devices.
authors.affiliation: Department of Materials Science and Engineering, NUANCE Center, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Langli
authors.initials: L
authors.lastname: Luo
authors.forename: Jinsong
authors.initials: J
authors.lastname: Wu
authors.forename: Junming
authors.initials: J
authors.lastname: Xu
authors.forename: Vinayak P
authors.initials: VP
authors.lastname: Dravid
keywords: conversion/deconversion reaction; electron diffraction; in situ high-resolution electron microscopy; lithium-ion battery; metal oxide electrode