Lithiation of silica through partial reduction

Ban, Chunmei; Kappes, Branden B.; Xu, Qiang; Engtrakul, Chaiwat; Ciobanu, Cristian V.; Dillon, Anne C.; Zhao, Yufeng

doi:10.1063/1.4729743

Cited by 64 publications

(56 citation statements)

References 31 publications

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“…This relation holds for the one dimensional bulk conduction along the c axis. In an effective or average way, we will adopt this Arhennius relation for the slow paths as well, since both in the grain boundary and perpendicular to the c axis the Li ion diffusion is more likely to occur by hoping rather than by partial attack of Li ions on the Si–O bonds . The assumption that Equation is valid for 1‐D conduction in bulk and for the slow pathways reflects the details of ionic conduction.…”

Section: Resultsmentioning

confidence: 99%

“…In an effective or average way, we will adopt this Arhennius relation for the slow paths as well, since both in the grain boundary and perpendicular to the c axis the Li ion diffusion is more likely to occur by hoping rather than by partial attack of Li ions on the Si-O bonds. 58 The assumption that Equation 1 is valid for 1-D conduction in bulk and for the slow pathways reflects the details of ionic conduction. Certain conduction mechanisms in other systems can rely on activation of an electrochemical reaction followed by hopping; 49 as such, the relevant energy barrier is the sum of the activation energy barrier of the reaction plus the barrier for hopping.…”

Section: Resultsmentioning

confidence: 99%

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Thermal regimes of Li‐ion conductivity in β‐eucryptite

et al. 2017

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While it is well-established that ionic conduction in lithium aluminosilicates proceeds via hopping of Li ions, the nature of the various hoping-based mechanisms in different temperature regimes has not been fully elucidated. The difficulties associated with investigating the conduction have to do with the presence of grains and grain boundaries of different orientations in these usually polycrystalline materials. Herein, we use electrochemical impedance spectroscopy (EIS) to investigate the ion conduction mechanisms in b-eucryptite, which is a prototypical lithium aluminosilicate. In the absence of significant structural transitions in grain boundaries, we find that there are three conduction regimes for the one-dimensional ionic motion along the c axis channels in the grains, and determine the activation energies for each of these temperature regimes. Activation energies computed from molecular statics calculations of the potential energy landscape encountered by Li ions suggest that at temperatures below 440°C conduction proceeds via cooperative or correlated motion, in agreement with established literature. Between 440°C and 500°C, the activation barriers extracted from EIS measurements are large and consistent with those from atomistic calculations for uncorrelated Li ion hopping. Above 500°C the activation barriers decrease significantly, which indicates that after the transition to the Li-disordered phase of b-eucryptite, the Li ion motion largely regains the correlated character. K E Y W O R D Saluminosilicates, impedance spectroscopy, ionic conduction, lithium 1 | INTRODUCTION As a prototype of lithium aluminum silicates (LAS), b-eucryptite (LiAlSiO 4 ) has attracted both fundamental and technological interest for decades due to its phase transformations, 1-5 unusual thermo-mechanical properties, 6-10 and the one-dimensional nature of its ionic conduction. [11][12][13][14][15] The superior Li ion conduction makes b-eucryptite a promising candidate for electrolyte applications, including thermal batteries and high-temperature solid electrodes. [16][17][18] Furthermore, applications such as electrothermal devices as well as thermal shock resistant structures can benefit from the overall negative coefficient of thermal expansion (CTE) of b-eucryptite. 8,9,16,17,[19][20][21][22][23][24] The crystal structure of b-eucryptite (space group P6 4 22 or P6 2 22

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Thermal regimes of Li‐ion conductivity in β‐eucryptite

et al. 2017

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“…However, the absence of such peaks may be related, in some cases, to the small size of SiO 2 [40] and slow kinetics related to their confinement in the carbon matrix. The observed gradual increase of the specific capacity during cycling was explained in the literature by the reduction of SiO 2 with the formation of Si which is able to insert more and more Li [4,19,20,41]. However, the mechanism behind is not well demonstrated.…”

Section: Methodsmentioning

confidence: 93%

Eco-friendly synthesis of SiO2 nanoparticles confined in hard carbon: A promising material with unexpected mechanism for Li-ion batteries

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Fullenwarth

Monconduit

et al. 2019

Carbon

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A fast, simple and environmentally friendly one-pot route to obtain carbon/SiO 2 hybrid materials is reported in this work. This consists in simple mixture of carbon and silica precursors, followed by thermal annealing at different temperatures. An interpenetrating hybrid network composed of hard carbon and amorphous SiO 2 nanoparticles (2e5 nm) homogeneously distributed was achieved. Increasing the annealing temperature from 600 C up to 1200 C, the material porosity and oxygen functional groups are gradually removed, while the amorphous nature of SiO 2 is conserved. This allows to diminish the irreversible capacity during the first charge-discharge cycle and to increase the reversible capacity. An excellent cycling capability, with a reversible capacity up to 535 mA hg-1 at C/5 constant current rate was obtained for C/SiO 2 materials used as anodes for Li-ion batteries. An atypical increase of the capacity during the first 50 cycles followed by a stable plateau up to 250 cycles was observed and related to electrolyte wettability limitation through the materials, particularly for those annealed at high temperatures which are more hydrophobic, less porous and the SiO 2 nanoparticles less accessible. The SiO 2 lithiation mechanism was evaluated by XRD, TEM and XPS post-mortem analyses and revealed the formation of reversible lithium silicate phases.

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“…Recently Ban et al . pointed out that the partial reduction of a‐SiO 2 leads to ∼4 eV decrease in the band gap and the layer becomes more ion‐permeable . Therefore oxygen‐rich amorphous SiO 1.85 is chosen as both the mechanical supporting layer and the electron path way in our structure, without sacrificing significantly the reversible capacity.…”

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