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Title: Morphology-controlled LiFePO{sub 4} cathodes by a simple polyol reaction for Li-ion batteries

LiFePO{sub 4} cathodes with secondary nanorod structures and nano-plate morphologies were synthesized by varying the reaction time in a polyol refluxing process without the use of any characteristic structure directing agents. The X-ray diffraction studies indicate the highly crystalline nature of the prepared samples. Electron microscopy investigations revealed the morphology of the samples after 1 to 16 h polyol reaction to be secondary nanorod bundles whereas the olivine sample recovered after 32 h polyol reaction displayed nano-plate morphology. The dimensions of the obtained samples varied from a few tens to a few hundred nanometers. When employed in a lithium test cell, the LiFePO{sub 4} cathodes reacted for 1, 4, 8, 16 and 32 h delivered discharge capacities of 161, 162, 171, 143 and 155 mAhg{sup −1}, respectively, with a well-defined plateau at 3.4 V and impressive capacity retentions until 50 cycles. Interestingly, among the prepared electrodes, the LiFePO{sub 4} nanorod bundle cathode prepared under 1 h reaction time maintained the highest average reversible capacities of 123 and 103 mAhg{sup −1} at C-rates as high as 3.2 and 6.4 C. The crystal growth mechanism during the polyol refluxing method can be explained by the stages of precursor dissolution and nucleation, orientedmore » crystal growth and alignment by self-assembly, aggregation and partial dissolution and complete re-crystallization. - Highlights: • Study of LiFePO{sub 4} crystal formation by tuning reaction times in a simple polyol process • Nano-structured LiFePO{sub 4} is formed by varying reaction times in a simple polyol process. • Self-assembled secondary LiFePO{sub 4} nanorod bundles are obtained under 1 h reaction time. • Secondary structures are formed via a template-free self-assembly process. • The olivine nanorod bundle cathode demonstrated enhanced electrochemical properties.« less
Authors:
; ; ; ;  [1] ;  [2] ;  [1]
  1. Department of Materials Science and Engineering, Chonnam National University, 300 Yongbongdong, Bukgu, Gwangju 500-757 (Korea, Republic of)
  2. Beamline Research Division, Pohang Accelerator Laboratory, Pohang 790-784 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22340337
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 89; Other Information: Copyright (c) 2014 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; AGGLOMERATION; CATHODES; CRYSTAL GROWTH; CRYSTALS; DISSOLUTION; ELECTRON MICROSCOPY; LITHIUM; LITHIUM ION BATTERIES; LITHIUM IONS; NANOSTRUCTURES; RECRYSTALLIZATION; X-RAY DIFFRACTION