1,720,972 research outputs found
Surface chemistry on LiCoPO4 electrodes in lithium cells: SEI formation and self-discharge
No full textIn this manuscript we investigate the surface chemistry of positive electrodes for Li-ion cell applications constituted by LiCoPO4 (LCP). This high potential material reversibly de-intercalates/intercalates lithium ions at 4-7-4.8 V vs. Li. However it suffers the occurrence of large irreversible capacity loss in the first galvanostatic cycle, capacity fading upon repeated cycling and self-discharge once fully charged up to 5 V vs. Li. These detrimental phenomena roots in the parasitic chemistry that occurs on the surface of the LCP electrodes upon cycling or in open circuit conditions after charge. Here we illustrate our recent findings about the evolution of LCP electrodes upon charge and self-discharge. The self-discharge in LCP electrodes is a self-feeding process that occurs with the spontaneous transfer of electrons from the electrolyte to the Co3+ ions in the de-lithiated electrode, mediated by a porous and partially reactive SEI film that is unable to fully passivate the electrode surface
A carbon-coated mixed olivine Li(Co1/3Fe1/3Mn1/3)PO4 material as positive electrode in lithium cells
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Insights of the complex side reactivity upon cycling of a full Li-ion LTO-LFP formulation
No full textGas release mitigation in LiFePO4-Li4Ti5O12 Li-ion pouch cells by an H2-selective getter
No full textIn this work we discuss the mitigation of H-2 accumulation upon cycling within a Li-ion battery (LIB) by the use of an hydrogen selective getter (i.e. Suisorb (TM)). This getter has been tested in electrochemical cells constituted by a Li4Ti5O12 (LTO) negative electrode material, a LiFePO4 (LFP) positive electrode material and a common liquid electrolyte (1 M solution of LiPF6 ethylene carbonate/dimethyl-carbonate) absorbed on a Celgard separator. LTO and LFP electrode performance has been analysed in lithium half cells and in full Li-ion configurations by galvanostatic cycling. The gas release within the LIB, assembled without and with the insertion of the getter, has been studied by electrochemical pressure tests to monitor the internal pressure within the cell and by gas chromatography to study the speciation of the gas. The modification of the electrode surface composition has been analysed by photoemission spectroscopy and the alteration in the morphology of the aluminium counter-collectors by electron microscopy. The incorporation of the Suisorb (TM) getter within LTO/LFP LIBs mitigates the accumulation of molecular hydrogen upon cycling, limits the LiPF6 hydrolysis and LiF formation and decreases the aluminium counter-collector pitting corrosion upon cycling. Furthermore also the battery performance are enhanced by the use of Suisorb (TM). (C) 2018 Elsevier Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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