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  • 1
    In: ACS Nano, American Chemical Society (ACS), Vol. 12, No. 3 ( 2018-03-27), p. 2909-2921
    Type of Medium: Online Resource
    ISSN: 1936-0851 , 1936-086X
    Language: English
    Publisher: American Chemical Society (ACS)
    Publication Date: 2018
    detail.hit.zdb_id: 2383064-5
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  • 2
    In: Journal of Power Sources, Elsevier BV, Vol. 413 ( 2019-02), p. 241-249
    Type of Medium: Online Resource
    ISSN: 0378-7753
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2019
    detail.hit.zdb_id: 1491915-1
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  • 3
    In: Chemistry of Materials, American Chemical Society (ACS), Vol. 26, No. 22 ( 2014-11-25), p. 6361-6370
    Type of Medium: Online Resource
    ISSN: 0897-4756 , 1520-5002
    Language: English
    Publisher: American Chemical Society (ACS)
    Publication Date: 2014
    detail.hit.zdb_id: 1500399-1
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  • 4
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2016-03, No. 2 ( 2016-06-10), p. 917-917
    Abstract: Graphitic carbon is extensively used as anode material in most of the commercial lithium-ion batteries due to its low cost and high coulombic efficiency. However, capacity of carbon anode (372mAh/g and 830mAh/mL) is limited by the reversible electrochemical intercalation of lithium ions in its structure. So, alternative research directions and different anode materials are currently being investigated with an aim to achieve high capacity and cycling stability. Recently, nano-material research has shed light on many high performing materials. Among these, metal oxide based materials such as SnO 2, MoO 2 , Co(OH) 2 have been recognized as one of the potential candidates for anode material of lithium–ion batteries because of its higher specific lithium storage capacity [1, 2, 3]. But, their poor capacity retention over long-term charge-discharge cycling due to low electrical conductivity has prevented its use as commercial anode material in lithium-ion batteries. Furthermore, during the electrochemical cycling, metal oxides typically break into small metal clusters, resulting in a large volume expansion and a loss of capacity [4] . For improving the performance of metal oxide based materials, nanostructured materials have received much attention as battery electrodes due to the short transport lengths for both electrons and Li ions, higher electrode-electrode contact area, and better accommodation of the strain of Li insertion/extraction [5]. Although there have been reports in the electrochemical behavior and performance improvement on metal oxide based anode materials for lithium ion batteries, it is still difficult to prove the reaction mechanism and abnormal capacity clearly. For accurate explanation of reaction mechanism and abnormal capacity, it is important to analyze each region systematically. Herein, we successfully synthesized nano-structured metal oxide materials through simple synthetic strategy. This research also included its novel reaction mechanism during electrochemical cycling with lithium. Structure and electrochemical properties of synthesized material were studied by diverse electrochemical tests, combination of the synchrotron radiation XRD and XAS techniques. Especially, the changes in the local structures during cycling were investigated systematically on the basis of XAS analysis. Based on these results, novel reaction mechanism about the nano-structured metal oxide based anode material during electrochemical cycling was suggested specifically. This finding will not only be helpful in a more complete understanding of the reaction mechanism of  metal oxide based anode materials but also will offer valuable guidance for developing new anode materials with abnormal high capacity for next generation rechargeable batteries. More detailed discussion will be presented at the time of meeting. [1]. Dong, Q et al., Materials Research Bulletin , 2011. 46(8): p. 1156-1162. [2]. I. A. Courtney and J. R. Dahn, J. Electrochem. Soc ., 1997, 144 , 2045 [3]. Wang, Z. Y et al., Chem. Commun. 2010, 46, 6906−6908 [4]. Poizot, P et al., Nature 2000, 407, 496−499 [5]. Maier, J et al., Nat. Mater. 2005, 4, 805−815.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2016
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  • 5
    Online Resource
    Online Resource
    The Electrochemical Society ; 2016
    In:  ECS Meeting Abstracts Vol. MA2016-02, No. 6 ( 2016-09-01), p. 894-894
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2016-02, No. 6 ( 2016-09-01), p. 894-894
    Abstract: Graphitic carbon is extensively used as anode material in most of the commercial lithium-ion batteries (LIBs) due to its low cost and high coulombic efficiency. However, capacity of carbon anode (372mAh/g and 830mAh/mL) is limited by the reversible electrochemical intercalation of lithium ions in its structure. So, alternative research directions and different anode materials are currently being investigated with an aim to achieve high capacity and cycling stability. Recently nano-material research has shed light on many high performing materials. Among these, cobalt hydroxide has been recognized as one of the potential candidates for anode materials because of its novel electric and electrochemical properties[1]. Co(OH) 2 with a sheet-like structure tends to form a layered assembly, thus it has the benefit of improved ion transport and better contact of electro-active materials with electrolyte. Several methods have been used to synthesize the hexagonal β-Co(OH) 2 nano sheets including facile hydrothermal and homogeneous precipitation with sodium hydroxide as the alkaline reagent. Co(OH) 2 -Graphene Nano Sheet (GNS) composite was reported in 2010[2] as anode material for LIBs with superior electrochemical performance and its reaction mechanism was suggested as: Co(OH) 2 + 2Li + +2e - → Co + 2LiOH (577mAh/g). GNS acted as synergistic effect to synthesized material for achieving higher capacity (1120mAh/g) because GNS could relieve the volume expansion during cycling and also, give excellent electronic conductivity. Co(OH) 2 -nanosheets/ Co 3 O 4 -nanoparticle hierarchical structure has also been reported[3] as anode material for LIB’s with enhanced capacity and performance. However, unlike the composite materials, bare Co(OH) 2 anode material still has trouble with showing good electrochemical performance for lithium ion batteries, which may be due to insufficient electrolyte soaking between layers and severe volume expansion during the cycling. Herein, we successfully synthesized colloidal silica assisted sheet-like nano-structured Co(OH) 2 using cobalt (Ⅱ) nitrate hexahydrate (Co(NO3)2∙6H2O, 97%, m.p. 55 ̊C, Aldrich) as precursor through simple synthetic strategy. Even though synthesized nano-structured Co(OH) 2 is not a composite material, shows excellent reversible capacity (~1000 mAh/g) during the electrochemical cycling beyond the theoretical capacity after the first irreversible discharge process, and exhibits excellent rate capability with a good cycle performance. This research also included its novel reaction mechanism during electrochemical cycling with lithium. Structural and electrochemical properties of synthesized material were studied by electrochemical tests and combination of the synchrotron radiation based X-ray diffraction (XRD)/ X-ray absorption spectroscopy (XAS) techniques. Changes in the bulk structure were studied by XRD whereas local structure changes around Co during cycling were systematically investigated by recorded XAS data. Based on these results, novel reaction mechanism about the nano-structured Co(OH) 2 anode material during electrochemical cycling was suggested specifically. This finding will not only be helpful in a more complete understanding of the reaction mechanism of metal oxide based anode materials but also will offer valuable guidance for developing new anode materials with abnormal high capacity for next generation rechargeable batteries. More detailed discussion will be presented at the time of meeting. [1]. Huang, X.-l et al., Journal of Materials Chemistry , 2012. 22(9): p. 3764. [2]. He, Y.-S et al., Electronbbn chemistry Communications , 2010. 12(4): p. 570-573. [3]. Dong, Q et al., Materials Research Bulletin , 2011. 46(8): p. 1156-1162.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2016
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  • 6
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2013-02, No. 14 ( 2013-10-27), p. 1014-1014
    Abstract: Abstract not Available.
    Type of Medium: Online Resource
    ISSN: 2151-2043
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2013
    detail.hit.zdb_id: 2438749-6
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  • 7
    In: ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2014-04, No. 2 ( 2014-06-10), p. 269-269
    Abstract: Graphitic carbon is widely used as anode material due to its low cost, good cycle life, and very stable capacity in most commercial lithium-ion batteries (LIBs). However, capacity of carbon anode (372mAh/g and 830mAh/mL) is limited by the reversible electrochemical intercalation of lithium ions in its structure. So, the search of new anode material has been ongoing to achieve the higher capacity. SnO 2 has been widely studied in the last decade as one of the potential candidates for anode materials due to its higher specific lithium storage capacity (783mAh/g). [1, 2] But, its poor capacity retention over long-term charge-discharge cycling has prevented its use as commercial anode material in LIBs. This problem has been associated with its alloying reaction which results in large volume changes of electrode material during electrochemical cycling. Also, an irreversible conversion reaction occurs prior to the alloying reaction, which results in the reduction of SnO 2 to Sn and formation of a non-decomposable Li 2 O matrix. Although there have been reports in the electrochemical behavior and performance improvement on SnO 2 as anode materials for Li-ion batteries, it is still difficult to prove the reaction mechanism and abnormal capacity clearly. For accurate explanation of reaction mechanism and abnormal capacity, it is important to analyze each region systematically. We studied mesoporous SnO 2 electrode material because of its higher abnormal capacity. Mesoporous SnO 2 was synthesized by sol-gel method by using the KIT-6 template. SEM & EDS were used to confirm the successful synthesis of this electrode material. Additionally, we performed diverse electrochemical tests such as EIS, GITT and cyclic voltammetry. The first discharge capacity of mesoporous SnO 2 was 2009.60mAh·g -1 and the charge capacity was 1048.43 mAh·g -1 . Compared with the theoretical specific capacity, the extra discharge capacity was associated with the formation of a solid electrolyte interphase (SEI) layer generated by an irreversible insertion/extraction of Li-ions into host structures or Li alloying reactions and by possible interfacial Li storage. In this work, we have tried to explain the electrochemical reaction mechanism of meso-porous SnO 2 by using ex situ X-ray Diffraction (XRD) and X-ray Absorption Spectroscopy (XAS) during cycles. Before the experiment, we were subdividing points in discharge/charge curves. Fig. 1 (a) shows ex-situ XRD patterns during first discharge of mesoporous SnO 2 which clearly show that SnO 2 structure changed into amorphous phase after point 4. Upon discharging below 0.2V amorphous SnO 2 phase converts into metallic phases which are indicated by broad peaks around 22 and 38 degree. To further study the mechanism we carried out ex-situ XAS measurements on mesoporous SnO 2 anode samples (Fig. 1 (b)). The peaks at 1.59Å and 2.60Å in the Fourier transform spectrum of extended X-ray absorption fine structure (EXAFS) represent Sn-O bond and Li-Sn bonds, respectively. [3] Irreversible capacity during first cycle of SnO 2 is related to conversion reaction and Li 4.4 Sn is formed as a product of alloying reaction. Sn-O peak intensity was decreased gradually by progressing discharge and Li- Sn peak was revealed by alloying reaction after point 3. Moreover, through the EXAFS data of the first charge, we can verify the existence of Sn-O bond of conversion reaction at the last region and conversion reaction is associated with capacity of mesoporous SnO 2 after initial discharge. These results were related to high abnormal capacity of mesoporous SnO 2 and more detailed discussion will be presented at the time of meeting. 1. I. A. Courtney and J. R. Dahn, J. Electrochem. Soc ., 144 , 2045 (1997) 2. I. A. Courtney and J.R. Dahn, J. Electrochem. Soc ., 144 , 2943 (1997) 3. A. N. Mansour, S. Mukerjee, X. Q. Yang and J. McBreen, J. Electrochem. Soc ., 147 , 869 (2000)
    Type of Medium: Online Resource
    ISSN: 2151-2043
    Language: Unknown
    Publisher: The Electrochemical Society
    Publication Date: 2014
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