Supercritical Fluid Synthesis of LiCoPO4 Nanoparticles and Their Application to Lithium Ion Battery

Devaraju, Murukanahally Kempaiah; Truong, Quang Duc; Hyodo, Hiroshi; Tomai, Takaaki; Honma, Itaru

doi:10.3390/inorganics2020233

Cited by 11 publications

(13 citation statements)

References 55 publications

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“…No crystalline impurity phases which are generally reported for products from solution-based routes (e.g. the poorly soluble Li3PO4) 65 are observed within the detection limit of the method. In contrast to conventional hydro-or solvothermal products, which are prone to antisite defects and disordered structures 37 and therefore often have to undergo thermal treatments at very high temperatures (~800-900 °C) to improve electrochemical activity, 39,42 the microwave technique delivers a highly crystalline LiCoPO4 material within a short reaction time of only 30 min and without any post heat treatment.…”

Section: Electrochemical Measurementsmentioning

confidence: 80%

Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO₄ as a high-voltage cathode material for lithium-ion batteries

et al. 2016

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† Electronic Supplementary Information (ESI) available: State of the art of HT, ST, SCF, MWHT, and MWST synthesis of LCP; PXRD measurement of an empty capillary; PXRD of Li2SO4 • H2O obtained from the reaction solution; Rietveld fit of LCP-MW-w; cell parameters, atomic coordinates, thermal displacement parameters, and selected interatomic distances obtained from all Rietveld refinements; TGA/DSC and temperature-dependent in situ PXRD data of LCP-MW; FTIR and Raman spectra; additional SEM images; additional electrochemical measurements of LCP-MW materials with varying amounts of Li2SO4 and of electrodes with high loading. See Olivine-type LiCoPO4 is considered a promising high-voltage cathode material for next-generation lithium-ion batteries. However, preparing high-performance LiCoPO4 by a simple approach has been challenging. Herein, we present a facile and rapid (30 min) one-step microwave-assisted solvothermal synthesis route using a 1:1 (v/v) water/ethylene glycol (EG) binary solvent mixture and a temperature of 250 °C. The technique delivers high-performance LiCoPO4 nanoparticles without additional post-annealing or carbon coating steps. The as-prepared powder consists of single crystalline LiCoPO4 and features a hexagonal platelet-like morphology with dimensions of 700-800 nm × 400-600 nm × 100-220 nm. Selected area electron diffraction (SAED) experiments reveal that the platelets show the smallest dimension along [010], which is the direction of the lithium diffusion pathways in the olivine crystal structure. Furthermore, the results indicate that the EG co-solvent plays an important role in tailoring the particle size, morphology, and crystal orientation of the material. Co L-edge soft X-ray absorption spectroscopy (XAS) of LiCoPO4 are presented for the first time and confirm that the material only consists of Co 2+ . Benefiting from the unique morphology, which facilitates Li-ion conduction, electrochemical measurements deliver an initial discharge capacity of 137 mAh/g at 0.1 C, a remarkably stable capacity retention of 68% after 100 cycles at 0.5 C, and a specific energy density of 658 Wh/kg based on its capacity and voltage, which is the best performance of LiCoPO4 obtained from microwave-assisted solvothermal synthesis to date.

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Section: Electrochemical Measurementsmentioning

confidence: 80%

Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO₄ as a high-voltage cathode material for lithium-ion batteries

et al. 2016

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“… 21 An atypical charging plateau occurred at 3.5 V versus Li/Li + on discharge, which has been previously reported. 22 The electrodes here had been calendared in order to improve their electrical conductivity, and the atypical plateau became significant after calendaring (see Supporting Information ). In this work, no impurities were detected by XRD, SIMS, or TEM imaging (see Supporting Information ).…”

Section: Results and Discussionmentioning

confidence: 99%

Visualization and Chemical Characterization of the Cathode Electrolyte Interphase Using He-Ion Microscopy and In Situ Time-of-Flight Secondary Ion Mass Spectrometry

Wheatcroft

Klingner

Heller

et al. 2020

ACS Appl. Energy Mater.

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Unstable cathode electrolyte interphase (CEI) formation increases degradation in high voltage Li-ion battery materials. Few techniques couple characterization of nano-scale CEI layers on the macroscale with in situ chemical characterization, and thus, information on how the underlying microstructure affects CEI formation is lost. Here, the process of CEI formation in a high voltage cathode material, LiCoPO 4 , has been investigated for the first time using helium ion microscopy (HIM) and in situ time-of-flight (ToF) secondary ion mass spectrometry (SIMS). The combination of HIM and Ne-ion ToF-SIMS has been used to correlate the cycle-dependent morphology of the CEI layer on LiCoPO 4 with a local cathode microstructure, including position, thickness, and chemistry. HIM imaging identified partial dissolution of the CEI layer on discharge resulting in in-homogenous CEI coverage on larger LiCoPO 4 agglomerates. Ne-ion ToF-SIMS characterization identified oxyfluorophosphates from HF attack by the electrolyte and a Li-rich surface region. Variable thickness of the CEI layer coupled with inactive Li on the surface of LiCoPO 4 electrodes contributes to severe degradation over the course of 10 cycles. The HIM–SIMS technique has potential to further investigate the effect of microstructures on CEI formation in cathode materials or solid electrolyte interphase formation in anodes, thus aiding future electrode development.

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“…Using supercritical fluid process we achieved direct synthesis of phase pure LiNiPO 4 due to the overwhelming advantages of this process as we reported in many of our previously published papers151617181920. The synthesis procedure for LiNiPO 4 cathode materials is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…To control the shape and morphology of cathode materials solution based synthesis is more suitable1. Recently, we have reported size and morphology controlled synthesis of variety of cathode materials such as phosphate, silicates and flurophosphates via a supercritical fluid process151617181920212223 and observe the improvement of electrochemical performances with related to size and shape.…”

mentioning

confidence: 99%

Synthesis, characterization and observation of antisite defects in LiNiPO4 nanomaterials

Devaraju

Truong

Hyodo

et al. 2015

Sci Rep

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Structural studies of high voltage cathode materials are necessary to understand their chemistry to improve the electrochemical performance for applications in lithium ion batteries. LiNiPO4 nanorods and nanoplates are synthesized via a one pot synthesis using supercritical fluid process at 450 oC for 10 min. The X-ray diffraction (XRD) analysis confirmed that LiNiPO4 phase is well crystallized, phase purity supported by energy dispersive spectroscopy (EDS) and elemental mapping by scanning electron transmission electron microscopy (STEM). For the first time, we have carried out direct visualization of atom-by-atom structural observation of LiNiPO4 nanomaterials using high-angle annular dark-field (HAADF) and annular bright-field (ABF) scanning transmission electron microscopy (STEM) analysis. The Rietveld refinement analysis was performed to find out the percentage of antisite defects presents in LiNiPO4 nanoplates and about 11% of antisite defects were found. Here, we provide the direct evidence for the presence of Ni atoms in Li sites and Li in Ni sites as an antisite defects are provided for understanding of electrochemical behavior of high voltage Li ion battery cathode materials.

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Supercritical Fluid Synthesis of LiCoPO4 Nanoparticles and Their Application to Lithium Ion Battery

Cited by 11 publications

References 55 publications

Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO₄ as a high-voltage cathode material for lithium-ion batteries

Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO₄ as a high-voltage cathode material for lithium-ion batteries

Visualization and Chemical Characterization of the Cathode Electrolyte Interphase Using He-Ion Microscopy and In Situ Time-of-Flight Secondary Ion Mass Spectrometry

Synthesis, characterization and observation of antisite defects in LiNiPO4 nanomaterials

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Supercritical Fluid Synthesis of LiCoPO4 Nanoparticles and Their Application to Lithium Ion Battery

Cited by 11 publications

References 55 publications

Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO4 as a high-voltage cathode material for lithium-ion batteries

Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO4 as a high-voltage cathode material for lithium-ion batteries

Visualization and Chemical Characterization of the Cathode Electrolyte Interphase Using He-Ion Microscopy and In Situ Time-of-Flight Secondary Ion Mass Spectrometry

Synthesis, characterization and observation of antisite defects in LiNiPO4 nanomaterials

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Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO₄ as a high-voltage cathode material for lithium-ion batteries

Facile, ethylene glycol-promoted microwave-assisted solvothermal synthesis of high-performance LiCoPO₄ as a high-voltage cathode material for lithium-ion batteries