Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate

Operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) studies of Ge anodes are carried out to understand the effect of cycling rate on Ge phase transformation during charge/discharge process and to relate that effect to capacity. It is discovered that the formation of crystalline...

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Main Authors: Lim, Linda Y., Fan, Shufen, Hng, Huey Hoon, Toney, Michael F.
Other Authors: School of Materials Science & Engineering
Format: Article
Language:English
Published: 2015
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Online Access:https://hdl.handle.net/10356/106069
http://hdl.handle.net/10220/26245
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1060692020-06-01T10:26:31Z Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate Lim, Linda Y. Fan, Shufen Hng, Huey Hoon Toney, Michael F. School of Materials Science & Engineering DRNTU::Engineering::Materials::Energy materials Operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) studies of Ge anodes are carried out to understand the effect of cycling rate on Ge phase transformation during charge/discharge process and to relate that effect to capacity. It is discovered that the formation of crystalline Li15Ge4 (c-Li15Ge4) during lithiation is suppressed beyond a certain cycling rate. A very stable and reversible high capacity of ≈1800 mAh g−1 can be attained up to 100 cycles at a slow C-rate of C/21 when there is complete conversion of Ge anode into c-Li15Ge4. When the C-rate is increased to ≈C/10, the lithiation reaction is more heterogeneous and a relatively high capacity of ≈1000 mAh g−1 is achieved with poorer electrochemical reversibility. An increase in C-rate to C/5 and higher reduces the capacity (≈500 mAh g−1) due to an impeded transformation from amorphous LixGe to c-Li15Ge4, and yet improves the electrochemical reversibility. A proposed mechanism is presented to explain the C-rate dependent phase transformations and the relationship of these to capacity fading. The operando XRD and XAS results provide new insights into the relationship between structural changes in Ge and battery capacity, which are important for guiding better design of high-capacity anodes. 2015-07-03T03:44:29Z 2019-12-06T22:04:04Z 2015-07-03T03:44:29Z 2019-12-06T22:04:04Z 2015 2015 Journal Article Lim, L. Y., Fan, S., Hng, H. H., & Toney, M. F. (2015). Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate. Advanced energy materials, 5(15), 1500599. 1614-6832 https://hdl.handle.net/10356/106069 http://hdl.handle.net/10220/26245 10.1002/aenm.201500599 en Advanced energy materials © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
institution Nanyang Technological University
building NTU Library
country Singapore
collection DR-NTU
language English
topic DRNTU::Engineering::Materials::Energy materials
spellingShingle DRNTU::Engineering::Materials::Energy materials
Lim, Linda Y.
Fan, Shufen
Hng, Huey Hoon
Toney, Michael F.
Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate
description Operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) studies of Ge anodes are carried out to understand the effect of cycling rate on Ge phase transformation during charge/discharge process and to relate that effect to capacity. It is discovered that the formation of crystalline Li15Ge4 (c-Li15Ge4) during lithiation is suppressed beyond a certain cycling rate. A very stable and reversible high capacity of ≈1800 mAh g−1 can be attained up to 100 cycles at a slow C-rate of C/21 when there is complete conversion of Ge anode into c-Li15Ge4. When the C-rate is increased to ≈C/10, the lithiation reaction is more heterogeneous and a relatively high capacity of ≈1000 mAh g−1 is achieved with poorer electrochemical reversibility. An increase in C-rate to C/5 and higher reduces the capacity (≈500 mAh g−1) due to an impeded transformation from amorphous LixGe to c-Li15Ge4, and yet improves the electrochemical reversibility. A proposed mechanism is presented to explain the C-rate dependent phase transformations and the relationship of these to capacity fading. The operando XRD and XAS results provide new insights into the relationship between structural changes in Ge and battery capacity, which are important for guiding better design of high-capacity anodes.
author2 School of Materials Science & Engineering
author_facet School of Materials Science & Engineering
Lim, Linda Y.
Fan, Shufen
Hng, Huey Hoon
Toney, Michael F.
format Article
author Lim, Linda Y.
Fan, Shufen
Hng, Huey Hoon
Toney, Michael F.
author_sort Lim, Linda Y.
title Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate
title_short Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate
title_full Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate
title_fullStr Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate
title_full_unstemmed Storage capacity and cycling stability in Ge anodes : relationship of anode structure and cycling rate
title_sort storage capacity and cycling stability in ge anodes : relationship of anode structure and cycling rate
publishDate 2015
url https://hdl.handle.net/10356/106069
http://hdl.handle.net/10220/26245
_version_ 1681058117806194688