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Title: Changes in Electronic Structure upon Li Deintercalation from LiCoPO4 Derivatives

Journal Article · · Chemistry of Materials
 [1];  [2];  [2];  [2];  [3];  [4];  [1];  [2];  [2]; ORCiD logo [1]
  1. Univ. of Illinois at Chicago, Chicago, IL (United States)
  2. U.S. Army Research Lab., Adelphi, MD (United States)
  3. Argonne National Lab. (ANL), Lemont, IL (United States)
  4. Naval Research Lab., Washington, D.C. (United States)
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On the path toward the design of Li-ion batteries with increased energy densities, efforts are focused on the development of positive electrodes that can maximize the voltage of the full cell. However, the development of novel materials that operate at high voltage, while also showing high efficiency and meeting strict safety standards, is an ongoing challenge. LiCoPO4 is being explored as a possible candidate, as the Co2+/3+ redox couple operates at 4.8 V versus Li+/Li0. The presence of phosphate groups is typically expected to stabilize the compound against oxygen loss, yet the changes in Co-O bonding upon Li extraction have not been ascertained. In addition, LiCoPO4 is riddled with problems relating to poor transport and strain in the crystal structure of the delithiated phase, which handicap its use as a high-voltage electrode. In this work, substituting ions to generate Li1.025Co0.84Fe0.10Cr0.05Si0.01(PO4)1.025 is found to stabilize both the electronic structure and crystal structure and, therefore, substantially improve the ability to fully utilize the redox capacity of the material. A thorough study by spectroscopic tools, combined with computations of the electronic structure, was used to probe changes in chemical bonding. The measurements revealed the existence of redox gradients between surface and bulk that are common in other materials that react at high potential. Lastly, the study offers a comprehensive understanding of the fundamental reactions in LiCoPO4-type frameworks, while further demonstrating that ion substitution is an effective tool for improving their performance.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
U.S. Army Research Laboratory; US Department of the Navy, Office of Naval Research (ONR); USDOE
Grant/Contract Number:
AC02-06CH11357
OSTI ID:
1464630
Journal Information:
Chemistry of Materials, Vol. 30, Issue 6; ISSN 0897-4756
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 25 works
Citation information provided by
Web of Science

References (29)

Challenges for Rechargeable Li Batteries journal February 2010
Ultimate Limits to Intercalation Reactions for Lithium Batteries journal October 2014
Building better batteries journal February 2008
Olivine LiCoPO[sub 4] as 4.8 V Electrode Material for Lithium Batteries journal January 1999
Improved cycle life of Fe-substituted LiCoPO4 journal October 2011
Reasons for capacity fading of LiCoPO4 cathodes in LiPF6 containing electrolyte solutions journal February 2012
Revealing Electrochemically Induced Antisite Defects in LiCoPO 4 : Evolution upon Cycling journal January 2015
Vanadium Substitution of LiFePO 4 Cathode Materials To Enhance the Capacity of LiFePO 4 -Based Lithium-Ion Batteries journal November 2012
Why Substitution Enhances the Reactivity of LiFePO 4 journal December 2012
Aliovalent Substitutions in Olivine Lithium Iron Phosphate and Impact on Structure and Properties journal April 2009
Cr and Si Substituted-LiCo0.9Fe0.1PO4: Structure, full and half Li-ion cell performance journal September 2016
Unit-cell refinement from powder diffraction scans journal December 1981
From ultrasoft pseudopotentials to the projector augmented-wave method journal January 1999
Projector augmented-wave method journal December 1994
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set journal October 1996
Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set journal July 1996
Band theory and Mott insulators: Hubbard U instead of Stoner I journal July 1991
Formation of Small Hole Polarons in Olivine Phosphate Cathode Materials journal May 2012
Transport properties of LiCoPO4 and Fe-substituted LiCoPO4 journal May 2014
Phase Transitions Occurring upon Lithium Insertion−Extraction of LiCoPO 4 journal February 2007
Identifying the Structure of the Intermediate, Li 2/3 CoPO 4 , Formed during Electrochemical Cycling of LiCoPO 4 journal October 2014
Chemistry and electrochemistry of composite LiFePO4 materials for secondary lithium batteries journal May 2006
Probing depth of soft x-ray absorption spectroscopy measured in total-electron-yield mode journal January 1992
Influence of crystal structure, ligand environment and morphology on Co L -edge XAS spectral characteristics in cobalt compounds journal October 2015
Determination of absorption coefficients for concentrated samples by fluorescence detection journal June 1993
Electronic structure and spin-state transition of LaCoO 3 journal June 1993
Phase Transformation and Lithiation Effect on Electronic Structure of Li x FePO 4 : An In-Depth Study by Soft X-ray and Simulations journal August 2012
Electronic structure of phospho-olivines LixFePO4 (x=0,1) from soft-x-ray-absorption and -emission spectroscopies journal November 2005
Ozonized single-walled carbon nanotubes investigated using NEXAFS spectroscopyElectronic supplementary information (ESI) available: experimental details of NEXAFS measurements and data processing. See http://www.rsc.org/suppdata/cc/b3/b315390h/ journal January 2004

Cited By (2)

Improving the Rate Capability of LiFePO 4 Electrode by Controlling Particle Size Distribution journal January 2019
Understanding and development of olivine LiCoPO 4 cathode materials for lithium-ion batteries journal January 2018

Figures / Tables (10)

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Table 1(p. 11)table Table 1
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Figure 9(p. 24)figure Figure 9

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