Young's modulus of polycrystalline Li22Si5

Ratchford, Joshua B.; Schuster, Brian E.; Crawford, B.; Lundgren, Cynthia A.; Allen, J. S.; Wolfenstine, J.

doi:10.1016/j.jpowsour.2011.04.042

Cited by 37 publications

(21 citation statements)

References 30 publications

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“…Young's modulus (a), hardness (b), and yield strength (c) of the 0.5 µm SiLi x thin films as a function of Li content in comparison to literature values of a‐S , c‐Si , Li , compacted c‐SiLi x powder , tension simulations by Zhao et al and MD simulations by Fan et al , respectively. Dotted lines were added as a guide for the eye.…”

Section: Resultsmentioning

confidence: 98%

Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

Zinn

Borhani-Haghighi

Ventosa

et al. 2014

Phys. Status Solidi A

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The mechanical properties of amorphous Si thin films, lithiated electrochemically to different Si-Li compositions are studied by ex situ nanoindentation. The compositions of the films are adjusted using an electrochemical routine that corrects for the Li consumed by SEI layer growth during initial lithiation. The mechanical properties such as Young's modulus and hardness are derived from nanoindentation. For compositions between Si and SiLi 2.5 the Young's modulus decreases with increasing Li content from $160 GPa to $8 GPa and the hardness decreases from $14 GPa to $0.1 GPa. The yield strength values, as deduced from hardness measurements, decrease from $5 GPa to 0.05 GPa. AFM imaging is used on the electrochemically cycled films to assess the SEIs impact on the nanomechanical measurements. XPS depth-profiling of the electrochemically cycled sample indicated a Li concentration gradient across the film thickness.

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Section: Resultsmentioning

confidence: 98%

Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

Zinn

Borhani-Haghighi

Ventosa

et al. 2014

Phys. Status Solidi A

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“…16 The quantitative utility of such models is dependent on measured elastoplastic properties, particularly the fracture toughness of these materials. To date, few experimental measurements of fracture toughness K Ic of battery materials have been reported; [17][18][19][20] similarly, few measurements of composition-dependent mechanical properties have been reported, with the exception of lithiated silicon for which both fracture toughness 19,21 and elastic constants [21][22][23][24][25][26][27] have been reported as functions of composition. Thus, the extent to which K Ic and other elastoplastic properties of ion-storage materials vary with lithium concentration, is understood poorly.…”

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confidence: 99%

“…28 Similarly, reduction of elastic moduli by a factor of 2-3 has been predicted computationally for lithiated silicon alloys 32 and verified experimentally. 19,[21][22][23][24][25][26][27] Mechanical property variations of this magnitude affect the stress distributions developed in electrochemically active materials. 29,33 Thus, the design and selection of mechanically robust battery electrode materials requires knowledge of how mechanical properties change during electrochemical cycling.…”

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confidence: 99%

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

Swallow

Woodford

McGrogan

et al. 2014

J. Electrochem. Soc.

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Mechanical degradation of lithium-ion battery (LIB) electrodes has been correlated with capacity fade and impedance growth over repeated charging and discharging. Knowledge of how the mechanical properties of materials used in LIBs are affected by electrochemical lithiation and delithiation could provide insight into design choices that mitigate mechanical damage and extend device lifetime. Here, we measured Young's modulus E, hardness H, and fracture toughness K Ic via instrumented nanoindentation of the prototypical intercalation cathode, Li X CoO 2 , after varying durations of electrochemical charging. After a single charge cycle, E and H decreased by up to 60%, while K Ic decreased by up to 70%. Microstructural characterization using optical microscopy, Raman spectroscopy, X-ray diffraction, and further nanoindentation showed that this degradation in K Ic was attributable to Li depletion at the material surface and was also correlated with extensive microfracture at grain boundaries. These results indicate that K Ic reduction and irreversible microstructural damage occur during the first cycle of lithium deintercalation from polycrystalline aggregates of Li X CoO 2 , potentially facilitating further crack growth over repeated cycling. Such marked reduction in K Ic over a single charge cycle also yields important implications for the design of electrochemical shock-resistant cathode materials. Energy storage is an enabling technology for electrified transportation and for large-scale deployment of renewable energy resources such as solar and wind. For many applications, non-aqueous ionintercalation chemistries such as Li-ion are attractive for their high energy density and electrochemical reversibility. However, the electrode materials used in ion-intercalation batteries undergo significant composition changes-which correlate to high storage capacity-that can induce structural changes and mechanical stresses; these changes can degrade battery performance metrics such as power, achievable storage capacity, and lifetime.1-8 Microstructural damage has been observed directly in numerous electrode materials subjected to electrochemical cycling, both within single crystals (or grains) and among polycrystalline aggregates. 4,5,[7][8][9][10][11][12][13][14][15] While the relationships among electrode microstructure, electrochemical cycling conditions, crystallographic changes in the active materials, and resulting mechanical stresses have been elucidated, relatively little is known about the composition-dependency of the key physical properties. Numerous models have been developed to predict mechanical deformation in ion-storage materials during electrochemical cycling, as recently reviewed by Mukhopadhyay and Sheldon. 16 The quantitative utility of such models is dependent on measured elastoplastic properties, particularly the fracture toughness of these materials. To date, few experimental measurements of fracture toughness K Ic of battery materials have been reported; [17][18][19][20] similarly, few measureme...

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“…In the estimation of the stress, the considered yield strength of Li x Si (s Y ) is 1.0 GPa, and E Si and E Li x Si are 180 and 35 GPa, respectively 15,16 . The ratio of the gap and initial thickness of crystalline Si (g/t 0 ) are 0.3, 0.6, 1.2, and 2.4.…”

Section: Resultsmentioning

confidence: 99%

Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

Lee¹

2015

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Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Here, we demonstrate physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. This study will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries.

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Young's modulus of polycrystalline Li22Si5

Cited by 37 publications

References 30 publications

Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

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Young's modulus of polycrystalline Li22Si5

Cited by 37 publications

References 30 publications

Mechanical properties of SiLixthin films at different stages of electrochemical Li insertion

Mechanical properties of SiLixthin films at different stages of electrochemical Li insertion

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of LiXCoO2

Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

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Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂