Effects of fluorine and chromium doping on the performance of lithium-rich Li1+xMO2 (M = Ni, Mn, Co) positive electrodes

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dc.contributor.authorPang, WKen_AU
dc.contributor.authorLin, HFen_AU
dc.contributor.authorLu, CZen_AU
dc.contributor.authorLiu, CEen_AU
dc.contributor.authorLiao, SCen_AU
dc.contributor.authorChen, JMen_AU
dc.contributor.authorPeterson, VKen_AU
dc.date.accessioned2018-09-11T04:29:39Zen_AU
dc.date.available2018-09-11T04:29:39Zen_AU
dc.date.issued2017-12-26en_AU
dc.date.statistics2017-07-25en_AU
dc.description.abstractLithium-rich metal oxides Li1+zMO2 (M = Ni, Co Mn, etc.) are promising positive electrode materials for high-energy lithium-ion batteries, with capacities of 250-300 mAh·g-1 that closely approach theoretical intercalation limits. Unfortunately, these materials suffer severe capacity fade on cycling, among other performance issues. While ion substitution can improve the performance of many of these materials, the underlying mechanisms of property modification are not completely understood. In this work we show enhanced performance of the Li1+zMO2 electrode, consisting of Li2MnO3 (with C2/m space group) and LiMO2 (with R3m space group) phases, and establish the effects of cationic and anionic substitution on the phase and structure evolution underpinning performance changes. While the undoped material has a high capacity of ∼270 mAh·g-1, only 79% of this remains after 200 cycles. Including ∼2% Cr in the material, likely at the R3m metal (3a) site, improved cycle performance by ∼13%, and including ∼5% F in the material, likely at the R3m oxygen (6c) site, enhanced capacity by ∼4-5% at the expense of a ∼12% decline in cycle performance. Moreover, Cr doping enhances energy density retention by ∼13%, and F doping suppresses this by 17%. We find that these changes arise by different mechanisms. Both anionic and cationic substitution promote faster Li diffusion, by 48% and 20%, respectively, as determined using cyclic voltammetry and leading to better rate performance. Unlike anionic substitution, cationic substitution enhances structural stability at the expense of some capacity, by suppressing lattice distortion during Li insertion and extraction. This work implicates strategic cationic-anionic codoping for enhanced electrochemical performance in lithium-rich layered metal-oxide phases. © 2017 American Chemical Society.en_AU
dc.identifier.citationPang, W. K., Lin, H. F., Peterson, V. K., Lu, C. Z., Liu, C. E., Liao, S. C., & Chen, J. M. (2017). Effects of Fluorine and Chromium Doping on the Performance of Lithium-Rich Li1+xMO2 (M = Ni, Mn, Co) Positive Electrodes. Chemistry of Materials, 29(24), 10299-10311. doi:10.1021/acs.chemmater.7b02930en_AU
dc.identifier.govdoc9104en_AU
dc.identifier.issn0897-4756en_AU
dc.identifier.issue24en_AU
dc.identifier.journaltitleChemistry of Materialsen_AU
dc.identifier.pagination10299-10311en_AU
dc.identifier.urihttps://pubs.acs.org/doi/abs/10.1021/acs.chemmater.7b02930en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/8957en_AU
dc.identifier.volume29en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectLithiumen_AU
dc.subjectMetalsen_AU
dc.subjectDiffusionen_AU
dc.subjectCharged particlesen_AU
dc.subjectElectric chargesen_AU
dc.subjectIonsen_AU
dc.subjectDiffusionen_AU
dc.titleEffects of fluorine and chromium doping on the performance of lithium-rich Li1+xMO2 (M = Ni, Mn, Co) positive electrodesen_AU
dc.typeJournal Articleen_AU
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