Reactive Flow in Silicon Electrodes Assisted by the Insertion of Lithium

Zhao, Kejie; Tritsaris, Georgios A.; Pharr, Matt; Wang, Wei L.; Okeke, Onyekwelu U.; Suo, Zhiyong; Vlassak, Joost J.; Kaxiras, Efthimios

doi:10.1021/nl302261w

Cited by 160 publications

(152 citation statements)

References 51 publications

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“…These data fit well to a power law relationship between the plastic strain rate and the stress. Additionally, our results indicate no evidence of the "reactive-flow" effect in a-Li x Si, as has been suggested in literature [27,30]. They do, however, provide insight into the unusual ability of a-Li x Si to flow plastically, while fracturing in a brittle manner.…”

Section: Introductionsupporting

confidence: 56%

“…The working area of each silicon electrode is 8 mm by 30 mm. We have previously performed x-ray diffraction experiments to confirm that the silicon films are amorphous under these sputtering conditions [27].…”

Section: Methodsmentioning

confidence: 99%

“…A number of studies have examined plastic deformation in Li x Si [5,12,18,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Sethuraman et al measured stresses during cycling of Li x Si electrodes, finding plastic flow, which results in dissipation of energy comparable to that of polarization losses [18].…”

Section: Introductionmentioning

confidence: 99%

“…The applicability of this "reactive flow" theory to a-Li x Si remains an open question. A study from first-principles calculations found the lithiation reaction to markedly reduce the flow stress of a-Li x Si [27], while a molecular dynamics study found no such effects [25]. There are no experimental studies aimed at investigating these effects.…”

Section: Introductionmentioning

confidence: 99%

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Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Pharr

Suo

Vlassak

2014

Journal of Power Sources

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Silicon is a promising anode material for lithium-ion batteries due to its enormous theoretical energy density. Fracture during electrochemical cycling has limited the practical viability of silicon electrodes, but recent studies indicate that fracture can be prevented by taking advantage of lithiation-induced plasticity. In this paper, we provide experimental insight into the nature of plasticity in amorphous Li x Si thin films. To do so, we vary the rate of lithiation of amorphous silicon thin films and simultaneously measure stresses. An increase in the rate of lithiation results in a corresponding increase in the flow stress. These observations indicate that rate-sensitive plasticity occurs in a-Li x Si electrodes at room temperature and at charging rates typically used in lithium-ion batteries. Using a simple mechanical model, we extract material parameters from our experiments, finding a good fit to a power law relationship between the plastic strain rate and the stress. These observations provide insight into the unusual ability of a-Li x Si to flow plastically, but fracture in a brittle manner. Moreover, the results have direct ramifications concerning the rate-capabilities of silicon electrodes: faster charging rates (i.e., strain rates) result in larger stresses and hence larger driving forces for fracture.

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Section: Introductionsupporting

confidence: 56%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Pharr

Suo

Vlassak

2014

Journal of Power Sources

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“…4,5 This, in turn, affects the degree to which mechanical stresses can be accommodated through plastic deformation rather than fracture. 6 Hence, a detailed understanding of the nature and kinetics of structural transitions that occur during lithiation and delithiation of silicon should provide insight into means of mediating the effects of mechanical stress on the cyclability of Si anodes.Electrochemically driven reactions between Li and Si have been studied under a variety of conditions, including at elevated and room temperature. Equilibrium titration experiments at 415…”

mentioning

confidence: 99%

Kinetic Study of the Initial Lithiation of Amorphous Silicon Thin Film Anodes

Miao

Thompson

2018

J. Electrochem. Soc.

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The mechanisms and kinetics of lithiation and delithiation of amorphous silicon were investigated using potentiostatic techniques and thin films of different thickness, with a focus on the initial lithiation process that occurs in the first cycle. In potentiostatic tests, distinct kinks were observed in the current vs. time curves, and the time at which the kink occurred increased for thicker films. This behavior can be explained using a model in which a sharp interface between an amorphous Li x Si phase and Li-saturated amorphous Si propagates through the film. Using this model, the rate-limiting process was determined to be diffusion of Li in the Li x Si phase rather than reaction at the lithiation front. The Li diffusivity in the lithiated phase was determined to be in the 10 −13 cm 2 /s range, independent of film thickness above 135 nm. The thin-film potentiostatic technique used in this study should prove useful in investigation of the mechanisms and rate parameters for other phase transitions that occur during lithiation of silicon and for kinetic studies of other electrode materials. Li-ion rechargeable batteries have been the focus of much research and development over recent decades. They power products ranging from electric vehicles to miniaturized electronic and medical devices. Due to its largest known capacity (8375 Ah/cm 3 , 3579 Ah/kg), Si is viewed as a promising anode material for batteries with high energy and power densities. Its abundance and relatively low cost also make it a practically feasible anode material.1 However, Si anodes suffer from capacity fade due to the very large volume expansion (up to 400%) 2 that occurs during lithiation and the consequent mechanical degradation it causes.3 In storing lithium, silicon goes through a sequence of structural transitions that affect the rate at which mechanical stress develops. 4,5 This, in turn, affects the degree to which mechanical stresses can be accommodated through plastic deformation rather than fracture. 6 Hence, a detailed understanding of the nature and kinetics of structural transitions that occur during lithiation and delithiation of silicon should provide insight into means of mediating the effects of mechanical stress on the cyclability of Si anodes.Electrochemically driven reactions between Li and Si have been studied under a variety of conditions, including at elevated and room temperature. Equilibrium titration experiments at 415• C show that four crystalline lithium silicide (Li x Si) phases form (Li 12 Si 7 , Li 7 Si 3 , Li 13 Si 4 and Li 22 Si 5 ).7-9 At room temperature, however, it is found using X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) that the equilibrium crystalline Li-Si phases are absent and the crystalline Li 15 Si 4 phase is observed only at the highest levels of lithiation.10 At lower levels of lithiation, metastable amorphous phases are formed instead.11 This phenomenon is similar to chemically driven solid-state amorphization reactions, 12 which are thought to be assoc...

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Nanostructured Silicon Anodes for High‐Performance Lithium‐Ion Batteries

Rahman

Song

Bhatt

et al. 2015

Adv Funct Materials

274

167

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Despite the high theoretical capacity of Si anodes, the electrochemical performance of Si anodes is hampered by severe volume changes during lithiation and delithiation, leading to poor cyclability and eventual electrode failure. Nanostructured silicon and its nanocomposite electrodes could overcome this problem holding back the deployment of Si anodes in lithium‐ion batteries (LIBs) by providing facile strain relaxation, short lithium diffusion distances, enhanced mass transport, and effective electrical contact. Here, the recent progress in nanostructured Si‐based anode materials such as nanoparticles, nanotubes, nanowires, porous Si, and their respective composite materials and fabrication processes in the application of LIBs have been reviewed. The ability of nanostructured Si materials in addressing the above mentioned challenges have been highlighted. Future research directions in the field of nanostructured Si anode materials for LIBs are summarized.

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Reactive Flow in Silicon Electrodes Assisted by the Insertion of Lithium

Cited by 160 publications

References 51 publications

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Kinetic Study of the Initial Lithiation of Amorphous Silicon Thin Film Anodes

Nanostructured Silicon Anodes for High‐Performance Lithium‐Ion Batteries

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