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Title: Improving the cycle stability of LiCoPO{sub 4} nanocomposites as 4.8 V cathode: Stepwise or synchronous surface coating and Mn substitution

Abstract

Nanostructured LiCo{sub 1−x}Mn{sub x}PO{sub 4}/C (x = 0 and 0.05) materials were successfully produced as superior quality cathodes by combined sol-gel and carbothermal reduction methods. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP), cyclic voltammetry (CV) and galvanostatic measurements were applied to determine the phase purity, morphology and electrochemical qualifications. HR-TEM analysis reveals that the thickness of the surface carbon layer of 5 to 10 nm range with the uniform distribution. LiCo{sub 0·95}Mn{sub 0·05}PO{sub 4}/C particles were between 40 and 80 nm and the same material exhibits a higher and stable reversible capacity (140 mA h g{sup −1}) with the long voltage plateau (4.76 V). Substitution of Co{sup 2+} with Mn{sup 2+} in LiCoPO{sub 4}/C has an influence on the initial discharge capacity and excellent cycling behaviour. The obtained results have attributed that production dynamics in nano-synthesis, the coating process with proper carbon source and an effective doping represent three parameters to prepare favorable cathode materials. - Highlights: • Structural, morphological and electrochemical effects of Mn doped LiCo{sub 1−x}Mn{sub x}PO{sub 4}–C electrodes are investigated. • Cheap, effective andmore » simple sol-gel assisted carbothermal reduction approach is used. • After 60th cycle, capacity retention is almost 92% for LiCo{sub 0·95}Mn{sub 0.05}PO{sub 4}–C electrode. • Mn-doped sample exhibits distinctive oxidation (4.76 V and 4.12 V) peaks.« less

Authors:
 [1];  [2];  [3]
  1. Kafkas University, Atatürk Vocational School of Health Science, Kars (Turkey)
  2. Sakarya University, Arifiye Vocational School, Sakarya (Turkey)
  3. Kafkas University, Faculty of Engineering and Architecture, Department of Bioengineering, Kars (Turkey)
Publication Date:
OSTI Identifier:
22587158
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 116; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; CATHODES; COBALT PHOSPHATES; DOPED MATERIALS; ELECTROCHEMISTRY; ELECTRON SCANNING; FIELD EMISSION; FOURIER TRANSFORM SPECTROMETERS; FOURIER TRANSFORMATION; INFRARED SPECTRA; NANOCOMPOSITES; NANOSTRUCTURES; SCANNING ELECTRON MICROSCOPY; SOL-GEL PROCESS; SURFACE COATING; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Örnek, Ahmet, E-mail: ahmetornek@kafkas.edu.tr, Can, Mustafa, and Yeşildağ, Ali. Improving the cycle stability of LiCoPO{sub 4} nanocomposites as 4.8 V cathode: Stepwise or synchronous surface coating and Mn substitution. United States: N. p., 2016. Web. doi:10.1016/J.MATCHAR.2016.04.009.
Örnek, Ahmet, E-mail: ahmetornek@kafkas.edu.tr, Can, Mustafa, & Yeşildağ, Ali. Improving the cycle stability of LiCoPO{sub 4} nanocomposites as 4.8 V cathode: Stepwise or synchronous surface coating and Mn substitution. United States. doi:10.1016/J.MATCHAR.2016.04.009.
Örnek, Ahmet, E-mail: ahmetornek@kafkas.edu.tr, Can, Mustafa, and Yeşildağ, Ali. 2016. "Improving the cycle stability of LiCoPO{sub 4} nanocomposites as 4.8 V cathode: Stepwise or synchronous surface coating and Mn substitution". United States. doi:10.1016/J.MATCHAR.2016.04.009.
@article{osti_22587158,
title = {Improving the cycle stability of LiCoPO{sub 4} nanocomposites as 4.8 V cathode: Stepwise or synchronous surface coating and Mn substitution},
author = {Örnek, Ahmet, E-mail: ahmetornek@kafkas.edu.tr and Can, Mustafa and Yeşildağ, Ali},
abstractNote = {Nanostructured LiCo{sub 1−x}Mn{sub x}PO{sub 4}/C (x = 0 and 0.05) materials were successfully produced as superior quality cathodes by combined sol-gel and carbothermal reduction methods. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP), cyclic voltammetry (CV) and galvanostatic measurements were applied to determine the phase purity, morphology and electrochemical qualifications. HR-TEM analysis reveals that the thickness of the surface carbon layer of 5 to 10 nm range with the uniform distribution. LiCo{sub 0·95}Mn{sub 0·05}PO{sub 4}/C particles were between 40 and 80 nm and the same material exhibits a higher and stable reversible capacity (140 mA h g{sup −1}) with the long voltage plateau (4.76 V). Substitution of Co{sup 2+} with Mn{sup 2+} in LiCoPO{sub 4}/C has an influence on the initial discharge capacity and excellent cycling behaviour. The obtained results have attributed that production dynamics in nano-synthesis, the coating process with proper carbon source and an effective doping represent three parameters to prepare favorable cathode materials. - Highlights: • Structural, morphological and electrochemical effects of Mn doped LiCo{sub 1−x}Mn{sub x}PO{sub 4}–C electrodes are investigated. • Cheap, effective and simple sol-gel assisted carbothermal reduction approach is used. • After 60th cycle, capacity retention is almost 92% for LiCo{sub 0·95}Mn{sub 0.05}PO{sub 4}–C electrode. • Mn-doped sample exhibits distinctive oxidation (4.76 V and 4.12 V) peaks.},
doi = {10.1016/J.MATCHAR.2016.04.009},
journal = {Materials Characterization},
number = ,
volume = 116,
place = {United States},
year = 2016,
month = 6
}
  • Here, large uncertainties in land surface models (LSMs) simulations still arise from inaccurate forcing, poor description of land surface heterogeneity (soil and vegetation properties), incorrect model parameter values and incomplete representation of biogeochemical processes. The recent increase in the number and type of carbon cycle-related observations, including both in situ and remote sensing measurements, has opened a new road to optimize model parameters via robust statistical model–data integration techniques, in order to reduce the uncertainties of simulated carbon fluxes and stocks. In this study we present a carbon cycle data assimilation system that assimilates three major data streams, namely themore » Moderate Resolution Imaging Spectroradiometer (MODIS)-Normalized Difference Vegetation Index (NDVI) observations of vegetation activity, net ecosystem exchange (NEE) and latent heat (LE) flux measurements at more than 70 sites (FLUXNET), as well as atmospheric CO 2 concentrations at 53 surface stations, in order to optimize the main parameters (around 180 parameters in total) of the Organizing Carbon and Hydrology in Dynamics Ecosystems (ORCHIDEE) LSM (version 1.9.5 used for the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations). The system relies on a stepwise approach that assimilates each data stream in turn, propagating the information gained on the parameters from one step to the next. Overall, the ORCHIDEE model is able to achieve a consistent fit to all three data streams, which suggests that current LSMs have reached the level of development to assimilate these observations. The assimilation of MODIS-NDVI (step 1) reduced the growing season length in ORCHIDEE for temperate and boreal ecosystems, thus decreasing the global mean annual gross primary production (GPP). Using FLUXNET data (step 2) led to large improvements in the seasonal cycle of the NEE and LE fluxes for all ecosystems (i.e., increased amplitude for temperate ecosystems). The assimilation of atmospheric CO 2, using the general circulation model (GCM) of the Laboratoire de Météorologie Dynamique (LMDz; step 3), provides an overall constraint (i.e., constraint on large-scale net CO 2 fluxes), resulting in an improvement of the fit to the observed atmospheric CO 2 growth rate. Thus, the optimized model predicts a land C (carbon) sink of around 2.2 PgC yr -1 (for the 2000–2009 period), which is more compatible with current estimates from the Global Carbon Project (GCP) than the prior value. The consistency of the stepwise approach is evaluated with back-compatibility checks. The final optimized model (after step 3) does not significantly degrade the fit to MODIS-NDVI and FLUXNET data that were assimilated in the first two steps, suggesting that a stepwise approach can be used instead of the more “challenging” implementation of a simultaneous optimization in which all data streams are assimilated together. Most parameters, including the scalar of the initial soil carbon pool size, changed during the optimization with a large error reduction. This work opens new perspectives for better predictions of the land carbon budgets.« less
  • LiCo{sub 1-x}M {sub x}PO{sub 4} (M = Mg{sup 2+}, Mn{sup 2+} and Ni{sup 2+}; 0 {<=} x {<=} 0.2) compounds have been synthesized by solid-state reaction method and studied as cathode materials for secondary lithium batteries. LiCoPO{sub 4} exhibits a discharge plateau at {approx}4.7 V with an initial discharge capacity of 125 mAh/g and on cycling capacity falls. Substitution of Co{sup 2+} with Mg{sup 2+}/Mn{sup 2+}/Ni{sup 2+} in LiCoPO{sub 4} has an influence on the initial discharge capacity and on cycling behaviour. The capacity retention of LiCoPO{sub 4} is improved by manganese substitution. Among the manganese substituted phases, LiCo{sub 0.95}Mn{submore » 0.05}PO{sub 4} shows good reversible capacity of {approx}50 mAh/g.« less
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