The Experts below are selected from a list of 167004 Experts worldwide ranked by ideXlab platform
J Y Wang - One of the best experts on this subject based on the ideXlab platform.
-
three dimensional atomic Scale Observation of structural evolution of cathode material in a working all solid state battery
Nature Communications, 2018Co-Authors: Yue Gong, Jie Nan Zhang, Qinghua Zhang, Y S Chen, Fanqi Meng, Jinan Shi, Xinyu Liu, Xiaozhi Liu, Hao Wang, J Y WangAbstract:Most technologically important electrode materials for lithium-ion batteries are essentially lithium ions plus a transition-metal oxide framework. However, their atomic and electronic structure evolution during electrochemical cycling remains poorly understood. Here we report the in situ Observation of the three-dimensional structural evolution of the transition-metal oxide framework in an all-solid-state battery. The in situ studies LiNi0.5Mn1.5O4 from various zone axes reveal the evolution of both atomic and electronic structures during delithiation, which is found due to the migration of oxygen and transition-metal ions. Ordered to disordered structural transition proceeds along the , , directions and inhomogeneous structural evolution along the direction. Uneven extraction of lithium ions leads to localized migration of transition-metal ions and formation of antiphase boundaries. Dislocations facilitate transition-metal ions migration as well. Theoretical calculations suggest that doping of lower valence-state cations effectively stabilize the structure during delithiation and inhibit the formation of boundaries.
-
in situ atomic Scale Observation of electrochemical delithiation induced structure evolution of licoo2 cathode in a working all solid state battery
Journal of the American Chemical Society, 2017Co-Authors: Yue Gong, Jie Nan Zhang, Xiqian Yu, Ruijuan Xiao, Liwei Jiang, Yongsheng Hu, Zhenzhong Yang, J Y Wang, Qinghua Zhang, Lin GuAbstract:We report a method for in situ atomic-Scale Observation of electrochemical delithiation in a working all-solid-state battery using a state-of-the-art chip based in situ transmission electron microscopy (TEM) holder and focused ion beam milling to prepare an all-solid-state lithium-ion battery sample. A battery consisting of LiCoO2 cathode, LLZO solid state electrolyte and gold anode was constructed, delithiated and observed in an aberration corrected scanning transmission electron microscope at atomic Scale. We found that the pristine single crystal LiCoO2 became nanosized polycrystal connected by coherent twin boundaries and antiphase domain boundaries after high voltage delithiation. This is different from liquid electrolyte batteries, where a series of phase transitions take place at LiCoO2 cathode during delithiation. Both grain boundaries become more energy favorable along with extraction of lithium ions through theoretical calculation. We also proposed a lithium migration pathway before and after po...
Yue Gong - One of the best experts on this subject based on the ideXlab platform.
-
three dimensional atomic Scale Observation of structural evolution of cathode material in a working all solid state battery
Nature Communications, 2018Co-Authors: Yue Gong, Jie Nan Zhang, Qinghua Zhang, Y S Chen, Fanqi Meng, Jinan Shi, Xinyu Liu, Xiaozhi Liu, Hao Wang, J Y WangAbstract:Most technologically important electrode materials for lithium-ion batteries are essentially lithium ions plus a transition-metal oxide framework. However, their atomic and electronic structure evolution during electrochemical cycling remains poorly understood. Here we report the in situ Observation of the three-dimensional structural evolution of the transition-metal oxide framework in an all-solid-state battery. The in situ studies LiNi0.5Mn1.5O4 from various zone axes reveal the evolution of both atomic and electronic structures during delithiation, which is found due to the migration of oxygen and transition-metal ions. Ordered to disordered structural transition proceeds along the , , directions and inhomogeneous structural evolution along the direction. Uneven extraction of lithium ions leads to localized migration of transition-metal ions and formation of antiphase boundaries. Dislocations facilitate transition-metal ions migration as well. Theoretical calculations suggest that doping of lower valence-state cations effectively stabilize the structure during delithiation and inhibit the formation of boundaries.
-
in situ atomic Scale Observation of electrochemical delithiation induced structure evolution of licoo2 cathode in a working all solid state battery
Journal of the American Chemical Society, 2017Co-Authors: Yue Gong, Jie Nan Zhang, Xiqian Yu, Ruijuan Xiao, Liwei Jiang, Yongsheng Hu, Zhenzhong Yang, J Y Wang, Qinghua Zhang, Lin GuAbstract:We report a method for in situ atomic-Scale Observation of electrochemical delithiation in a working all-solid-state battery using a state-of-the-art chip based in situ transmission electron microscopy (TEM) holder and focused ion beam milling to prepare an all-solid-state lithium-ion battery sample. A battery consisting of LiCoO2 cathode, LLZO solid state electrolyte and gold anode was constructed, delithiated and observed in an aberration corrected scanning transmission electron microscope at atomic Scale. We found that the pristine single crystal LiCoO2 became nanosized polycrystal connected by coherent twin boundaries and antiphase domain boundaries after high voltage delithiation. This is different from liquid electrolyte batteries, where a series of phase transitions take place at LiCoO2 cathode during delithiation. Both grain boundaries become more energy favorable along with extraction of lithium ions through theoretical calculation. We also proposed a lithium migration pathway before and after po...
Ze Zhang - One of the best experts on this subject based on the ideXlab platform.
-
in situ atomic Scale Observation of grain size and twin thickness effect limit in twin structural nanocrystalline platinum
Nature Communications, 2020Co-Authors: Lihua Wang, Kui Du, Chengpeng Yang, Jiao Teng, Libo Fu, Ze ZhangAbstract:Twin-thickness-controlled plastic deformation mechanisms are well understood for submicron-sized twin-structural polycrystalline metals. However, for twin-structural nanocrystalline metals where both the grain size and twin thickness reach the nanometre Scale, how these metals accommodate plastic deformation remains unclear. Here, we report an integrated grain size and twin thickness effect on the deformation mode of twin-structural nanocrystalline platinum. Above a ∼10 nm grain size, there is a critical value of twin thickness at which the full dislocation intersecting with the twin plane switches to a deformation mode that results in a partial dislocation parallel to the twin planes. This critical twin thickness value varies from ∼6 to 10 nm and is grain size-dependent. For grain sizes between ∼10 to 6 nm, only partial dislocation parallel to twin planes is observed. When the grain size falls below 6 nm, the plasticity switches to grain boundary-mediated plasticity, in contrast with previous studies, suggesting that the plasticity in twin-structural nanocrystalline metals is governed by partial dislocation activities. The deformation mechanisms of micron-sized twinned metals are well-understood, but it is not so for twinned nanocrystalline metals. Here, the authors use high resolution microscopy to image the deformation of nanocrystalline twinned platinum and show that grain boundary behaviors dominate plasticity below 6 nm.
-
Atomic Scale Observation of a defect-mediated first-order phase transition in VO2(A)
Nanoscale, 2017Co-Authors: Chao Jiang, Zhengfei Zhang, Yong Wang, Lu Chen, Jun Liu, Ping Jin, Ze ZhangAbstract:The study of first-order structural transformations has attracted extensive attention due to their significant scientific and industrial importance. However, it remains challenging to exactly determine the nucleation sites at the very beginning of the transformation. Here, we report the atomic Scale real-time Observation of a unique defect-mediated reversible phase transition between the low temperature phase (LTP) and the high temperature phase (HTP) of VO2(A). In situ Cs-corrected scanning transmission electron microscopy (STEM) images clearly indicate that both phase transitions (from the HTP to the LTP and from the LTP to the HTP) start at the defect sites in parent phases. Intriguingly, the structure of the defects within the LTP is demonstrated to be the HTP of VO2 (A), and the defect in the HTP of VO2(A) is determined to be the LTP structure of VO2(A). These findings are expected to broaden our current understanding of the first-order phase transition and shed light on controlling materials’ structure–property phase transition by “engineering” defects in applications.
-
Atomic-Scale Observation of pressure-dependent reduction dynamics of W18O49 nanowires using environmental TEM.
Physical chemistry chemical physics : PCCP, 2017Co-Authors: Zhengfei Zhang, Ze Zhang, Liping Sheng, Lu Chen, Yong WangAbstract:The real-time Observation of structural evolution of materials can provide critical information for understanding their reduction mechanisms under different environments. Herein, we report the atomic-Scale Observation of the reduction dynamics of W18O49 nanowires (NWs) using environmental transmission electron microscopy. Intriguingly, the reduction pathway is found to be affected by oxygen pressure. Under high oxygen pressure (∼0.095 Pa), a W18O49 NW epitaxially transforms into a WO2 NW via mass transport across the interface between (010)W18O49 and (101)WO2. While under low oxygen pressure (∼0.0004 Pa), the transformation follows the sequence of W18O49(NW) → WO2(NW) → β-W(nanoparticles), which is identified as a new reduction pathway. These findings reveal the pressure-dependent reduction and a new transformation pathway, and extend our current understanding of the reduction dynamics of metal oxides.
-
atomic Scale Observation of vapor solid nanowire growth via oscillatory mass transport
ACS Nano, 2016Co-Authors: Zhengfei Zhang, Yong Wang, Wentao Yuan, Xiao Feng Zhang, Chenghua Sun, Ze ZhangAbstract:In situ atomic-Scale transmission electron microscopy (TEM) can provide critical information regarding growth dynamics and kinetics of nanowires. A catalyst-aided nanowire growth mechanism has been well-demonstrated by this method. By contrast, the growth mechanism of nanowires without catalyst remains elusive because of a lack of crucial information on related growth dynamics at the atomic level. Herein, we present a real-time atomic-Scale Observation of the growth of tungsten oxide nanowires through an environmental TEM. Our results unambiguously demonstrate that the vapor–solid mechanism dominates the nanowire growth, and the oscillatory mass transport on the nanowire tip maintains the noncatalytic growth. Autocorrelation analysis indicates that adjacent nucleation events in the nanowire growth are independent of each other. These findings may improve the understanding of the vapor–solid growth mechanism of nanowires.
-
in situ atomic Scale Observation of twinning dominated deformation in nanoScale body centred cubic tungsten
Nature Materials, 2015Co-Authors: Jiangwei Wang, Ze Zhang, Zhi Zeng, Christopher R Weinberger, Ting Zhu, Scott X MaoAbstract:Little is known about the micromechanisms by which deformation twinning occurs in body-centred cubic crystals. An atomic-Scale microscopy study now provides new insight, by the in situ testing of tungsten nanowires.
Ronny Neumann - One of the best experts on this subject based on the ideXlab platform.
-
Real-time molecular Scale Observation of crystal formation
Nature Chemistry, 2017Co-Authors: Roy E. Schreiber, Zhong Ling Lang, Josep Mar\'ia Poblet, Sharon G. Wolf, Lothar Houben, Jorge J. Carbó, Gregory Leitus, Ronny NeumannAbstract:How molecules in solution form crystal nuclei, which then grow into large crystals, is a poorly understood phenomenon. The classical mechanism of homogeneous crystal nucleation proceeds via the spontaneous random aggregation of species from liquid or solution. However, a non-classical mechanism suggests the formation of an amorphous dense phase that reorders to form stable crystal nuclei. So far it has remained an experimental challenge to observe the formation of crystal nuclei from five to thirty molecules. Here, using polyoxometallates, we show that the formation of small crystal nuclei is observable by cryogenic transmission electron microscopy. We observe both classical and non-classical nucleation processes, depending on the identity of the cation present. The experiments verify theoretical studies that suggest non-classical nucleation is the lower of the two energy pathways. The arrangement in just a seven-molecule proto-crystal matches the order found by X-ray diffraction of a single bulk crystal, which demonstrates that the same structure was formed in each case. Homogeneous crystal nucleation has now been observed by transmission electron microscopy in real time on a molecular Scale. Countercation-dependent Observations of polyoxometalate proto-crystal formation confirm existence of a higher energy classical molecular attachment mechanism, as well as a lower energy two-step mechanism via an intermediate dense phase.
-
Real-time molecular Scale Observation of crystal formation
Nature Chemistry, 2016Co-Authors: Roy E. Schreiber, Zhong Ling Lang, Josep Mar\'ia Poblet, Sharon G. Wolf, Lothar Houben, Jorge J. Carbó, Gregory Leitus, Ronny NeumannAbstract:Homogeneous crystal nucleation has now been observed by transmission electron microscopy in real time on a molecular Scale. Countercation-dependent Observations of polyoxometalate proto-crystal formation confirm existence of a higher energy classical molecular attachment mechanism, as well as a lower energy two-step mechanism via an intermediate dense phase.
-
Real-time molecular Scale Observation of crystal formation
Nature chemistry, 2016Co-Authors: Roy E. Schreiber, Zhong Ling Lang, Josep Mar\'ia Poblet, Sharon G. Wolf, Lothar Houben, Jorge J. Carbó, Gregory Leitus, Ronny NeumannAbstract:How molecules in solution form crystal nuclei, which then grow into large crystals, is a poorly understood phenomenon. The classical mechanism of homogeneous crystal nucleation proceeds via the spontaneous random aggregation of species from liquid or solution. However, a non-classical mechanism suggests the formation of an amorphous dense phase that reorders to form stable crystal nuclei. So far it has remained an experimental challenge to observe the formation of crystal nuclei from five to thirty molecules. Here, using polyoxometallates, we show that the formation of small crystal nuclei is observable by cryogenic transmission electron microscopy. We observe both classical and non-classical nucleation processes, depending on the identity of the cation present. The experiments verify theoretical studies that suggest non-classical nucleation is the lower of the two energy pathways. The arrangement in just a seven-molecule proto-crystal matches the order found by X-ray diffraction of a single bulk crystal, which demonstrates that the same structure was formed in each case.
Lin Gu - One of the best experts on this subject based on the ideXlab platform.
-
in situ atomic Scale Observation of electrochemical delithiation induced structure evolution of licoo2 cathode in a working all solid state battery
Journal of the American Chemical Society, 2017Co-Authors: Yue Gong, Jie Nan Zhang, Xiqian Yu, Ruijuan Xiao, Liwei Jiang, Yongsheng Hu, Zhenzhong Yang, J Y Wang, Qinghua Zhang, Lin GuAbstract:We report a method for in situ atomic-Scale Observation of electrochemical delithiation in a working all-solid-state battery using a state-of-the-art chip based in situ transmission electron microscopy (TEM) holder and focused ion beam milling to prepare an all-solid-state lithium-ion battery sample. A battery consisting of LiCoO2 cathode, LLZO solid state electrolyte and gold anode was constructed, delithiated and observed in an aberration corrected scanning transmission electron microscope at atomic Scale. We found that the pristine single crystal LiCoO2 became nanosized polycrystal connected by coherent twin boundaries and antiphase domain boundaries after high voltage delithiation. This is different from liquid electrolyte batteries, where a series of phase transitions take place at LiCoO2 cathode during delithiation. Both grain boundaries become more energy favorable along with extraction of lithium ions through theoretical calculation. We also proposed a lithium migration pathway before and after po...
