A transmission electron microscopy study of crack formation and propagation in electrochemically cycled graphite electrode in lithium-ion cells

Bhattacharya, Sandeep; Riahi, A.R.; Alpas, A.T.

doi:10.1016/j.jpowsour.2011.05.079

Cited by 80 publications

(65 citation statements)

References 36 publications

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“…[1][2][3][4][5][6][7][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.…”

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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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mentioning

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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“…This damage feature is consistent with those reported in the literature for carbon electrodes. [11,12,[51][52][53] It is likely that most damage to the uncoated CFs occurred prior to the establishment of the solid electrolyte layer. [7,8] …”

Section: Microstructural and Compositional Characterization Of Sn-mentioning

confidence: 99%

“…At high scan rates (>3.00 mV s À1 ), delamination of graphite layers by the formation and propagation of interlayer cracks adjacent to SEI/graphite interfaces occurred due to the diffusion of co-intercalation products (Li 2 CO 3 , LiC 6 ) at the crack tips during the subsequent cycles. [12] Electrode surface modification is a common focus of the attempts made in order to improve the electrochemical performance. [13][14][15][16][17][18][19] For example, heating Li-ion cells containing graphite electrodes at 333 K (60°C) in an EC-based electrolyte was found to generate a Li 2 CO 3 -enriched SEI on graphite surface, which in turn ensued a 28 pct increase in the battery capacity when subsequently tested at 298 K (25°C).…”

Section: Introductionmentioning

confidence: 99%

Microstructural Characterization of Nanocrystalline Sn-Coated Carbon Fibre Electrodes Cycled in Li-Ion Cells

Bhattacharya

Shafiei

Alpas

2015

Metallurgical and Materials Transactions E

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The mechanisms of electrochemical capacity retention and eventual degradation in composite anodes prepared by electrodepositing nanocrystalline Sn coating on carbon fibres (CF), Sn-CF, were studied using in situ optical microscopy, high-resolution scanning and transmission electron microscopy. Specific capacity changes of Sn-CF anodes (vs Li/Li + ) were observed to take place in three stages: during the first two galvanostatic cycles, a rapid capacity decrease (from 1045 to 930 mAh g À1 ) occurred, which was followed by a steady-state stage where the capacity remained constant at 922 ± 22 mAh g À1 . The fast capacity drop of Sn-CF in the first cycle was attributed to the partial decohesion of Sn from CFs although the carbon substrate remained unaffected due to formation of a layer from the solid electrolyte reduction products. The pure Sn electrode with a higher initial specific capacity than the Sn-CF displayed a rapid decrease in the same range, whereas the specific capacity of the uncoated CF was already much lower as the fibres were severely damaged in the first cycle.

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“…Lithium intercalation in between the graphene layers leads to the formation of LiC 6 , which results in a low theoretical capacity of graphite that is 372 mA h g −1 . Although graphite anodes provide good life cycle performance and high coulombic efficiency [2,3], they suffer from severe damage in the first cycle due to lithiation and solvent co-intercalation that leads to a drastic drop in the specific capacity [4,5]. Once a solid electrolyte interphase (SEI) is formed on the electrode surfaces, solvent co-intercalation and, hence, damage is reduced [4,6] depending on the morphology and uniformity of the SEI [6].…”

Section: Introductionmentioning

confidence: 99%

A novel elevated temperature pre-treatment for electrochemical capacity enhancement of graphene nanoflake-based anodes

Bhattacharya

Alpas

2018

Mater Renew Sustain Energy

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Improvements in the specific capacity of graphene nanoflake-based anodes cycled vs. Li/Li + were investigated at two cycling temperatures of 25 and 50 °C. When cycled at 25 °C, the first cycle specific capacity of the graphene nanoflakes was 636 mA h g −1 , whereas cycling at 50 °C led to a 35% increase in the specific capacity to 856 mA h g −1 . High resolution SEM investigations revealed that the increased capacity of graphene cycled at 50 °C was accompanied by the formation of a uniform and continuous solid electrolyte interface (SEI). The strain generated in graphene anodes was reduced from 0.75% at 25 °C, to 0.12% at 50 °C, as determined by in situ Raman spectroscopy. This was attributed to the reduction in the extent of solvent co-intercalation at 50 °C. The results suggest that pre-cycling of Li-ion cell anodes containing graphene flakes at elevated temperatures would increase their specific capacity at the same charging/discharging current densities as that used for cycling at room temperature.

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A transmission electron microscopy study of crack formation and propagation in electrochemically cycled graphite electrode in lithium-ion cells

Cited by 80 publications

References 36 publications

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

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

Microstructural Characterization of Nanocrystalline Sn-Coated Carbon Fibre Electrodes Cycled in Li-Ion Cells

A novel elevated temperature pre-treatment for electrochemical capacity enhancement of graphene nanoflake-based anodes

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A transmission electron microscopy study of crack formation and propagation in electrochemically cycled graphite electrode in lithium-ion cells

Cited by 80 publications

References 36 publications

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

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

Microstructural Characterization of Nanocrystalline Sn-Coated Carbon Fibre Electrodes Cycled in Li-Ion Cells

A novel elevated temperature pre-treatment for electrochemical capacity enhancement of graphene nanoflake-based anodes

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

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