A nanoindentation study of the viscoplastic behavior of pure lithium

Wang, Yikai; Cheng, Yang‐Tse

doi:10.1016/j.scriptamat.2016.12.006

Cited by 68 publications

(44 citation statements)

References 39 publications

(55 reference statements)

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“…It has recently been demonstrated [65,75,76] that creep plays a critical role in understanding the mechanics of Li metal. Unfortunately for the purposes of our analysis, most creep work has examined more-or-less pure Li metal [65,70,75,76].…”

Section: Creep Of LImentioning

confidence: 99%

Rethinking How External Pressure Can Suppress Dendrites in Lithium Metal Batteries

Zhang

Wang

Harrison

et al. 2019

J. Electrochem. Soc.

129

115

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Lithium metal anodes are critical enablers for high energy density next generation batteries, but they suffer from poor morphology control and parasitic reactions. Recent experiments have shown that an external packing force on Li metal batteries with liquid electrolytes extends their lifetimes by inhibiting the growth of dendritic structures during Li deposition. However, the mechanisms by which pressure affects dendrite formation and growth have not been fully elucidated. For

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Section: Creep Of LImentioning

confidence: 99%

Rethinking How External Pressure Can Suppress Dendrites in Lithium Metal Batteries

Zhang

Wang

Harrison

et al. 2019

J. Electrochem. Soc.

129

115

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“…To reduce computational cost, both the sample and indenter tip were assumed to be axially symmetric. Therefore, twodimensional axially symmetric models were used [42]. Quadrilateral axisymmetric elements (CAX4R) were used to construct the finite element model, with fine enough meshes located around the indentation affected region to ensure the convergence of the simulation.…”

Section: Finite Element Modelingmentioning

confidence: 99%

Formation mechanism of abnormally large grains in a polycrystalline nickel-based superalloy during heat treatment processing

et al. 2019

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Controlling the final grain size in a uniform and controlled manner in powder metallurgy nickel-based superalloys is important since many mechanical properties are closely related to it. However, it has been widely documented that powder metallurgy superalloys are prone to suffer from growth of abnormally large grains (ALGs) during supersolvus heat treatment, which is harmful to in-service mechanical performance. The underlying mechanisms behind the formation of ALGs are not yet fully understood. In this research, ALGs were intentionally created using spherical indentation applied to a polycrystalline nickel-based superalloy at room temperature, establishing a deformation gradient underneath the indentation impression, which was quantitatively determined using finite element modelling, electron backscatter diffraction (EBSD) and synchrotron diffraction. Subsequent supersolvus heat treatment leads to the formation of ALGs in a narrow strain range, which also coincides with the contour of residual plastic strain in a range of about 2% to 10%. The formation mechanisms can be attributed to: (1) nucleation sites available for recrystallization are limited, (2) gradient distribution of stored energy across grain boundary. The proposed mechanisms were validated by the phase-field simulation. This research provides a deeper insight in understanding the formation of ALGs in polycrystalline nickel-based superalloy components during heat treatment, when subsurface plastic deformation caused by (mis)handling before super-solvus heat treatment occurs. The practical relevance of looking at small strains at room temperature this research is to understand what happens when turbine disks undergo small dents and scratches during (mis) handling before heat treatment.

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“…As the first step, contact area was introduced into a 1-dimensional (1-D) Newman model to simulate the discharge process of an all-solid-state Li-ion battery, which is composed of a metallic Li anode, LiCoO 2 positive electrode, and a LiPON-like solid electrolyte. Since Li metal has low hardness and exhibits creep behavior at room temperature, [36][37][38] it is more likely to maintain a good contact with the solid-electrolyte due to plastic deformation. This is consistent with the reported much higher exchange current density for the metallic Li electrode 39 than that for LiCoO 2 in all-solid-state Li-ion batteries.…”

mentioning

confidence: 99%

Simulation of the Effect of Contact Area Loss in All-Solid-State Li-Ion Batteries

Tian

2017

J. Electrochem. Soc.

122

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Maintaining the physical contact between the solid electrolyte and the electrode is important to improve the performance of all-solidstate batteries. Imperfect contact can be formed during cell fabrication and will be worsened due to cycling, resulting in degradation of the battery performance. In this paper, the effect of imperfect contact area was incorporated into a 1-D Newman battery model by assuming the current and Li concentration will be localized at the contacted area. Constant current discharging processes at different rates and contact areas were simulated for a film-type Li|LiPON|LiCoO 2 all-solid-state Li-ion battery. The capacity drop was correlated with the contact area loss. It was found at lower cutoff voltage, the correlation is almost linear with a slope of 1; while at a higher cutoff voltage, the dropping rate is slower. To establish the relationship between the applied pressure and the contact area, Persson's contact mechanics theory was applied, as it uses self-affined surfaces to simplify the multi-length scale contacts in all-solid-state batteries. The contact area and pressure were computed for both film-type and bulk-type all-solid-state Li-ion batteries. The model is then used to suggest how much pressures should be applied to recover the capacity drop due to contact area loss. Conventional Li-ion batteries usually include a liquid electrolyte, which facilitates Li-ions transport between cathode and anode. However, the applications of Li-ion batteries are still limited by the flammability and narrow electrochemical window of the liquid electrolytes. 1-3During the past decades, several solid electrolytes 4-9 with the ionic conductivity close to the liquid electrolyte have been developed, thus enabled the development of all-solid-state batteries. The benefits of all-solid-state batteries are high energy density, non-flammability, and the large electrochemical window (if the solid electrolyte form stable interphase layers on electrode surface). 10,11However, a major bottleneck for all-solid-state Li-ion batteries lies at the high interfacial resistance due to two main factors, chemical effect and physical contact. 3 The chemical effect refers to the chemical changes at the solid-electrolyte/electrode interface that cause slower transport. The chemical changes include the interphase layer formation due to solid electrolyte decomposition, 11 and/or Li-ion depletion zone at the interface 12 (for example, LiPON/Li 2 CO 3 ). Physical contact induced impedance comes from the imperfect contact at the solid-electrolyte/electrode interface, which plays a more important role for batteries using solid-electrolytes than the conventional batteries employing liquid electrolytes. Liquid electrolytes can easily diffuse through the porous electrode and wet the electrode surface, so, any fracture and disconnection between solid particles will only cause electrical disconnection. However, for solid electrolytes, the fracture and disconnection will impede Li-ion transport, as well as electron transport. Thus...

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A nanoindentation study of the viscoplastic behavior of pure lithium

Cited by 68 publications

References 39 publications

Rethinking How External Pressure Can Suppress Dendrites in Lithium Metal Batteries

Rethinking How External Pressure Can Suppress Dendrites in Lithium Metal Batteries

Formation mechanism of abnormally large grains in a polycrystalline nickel-based superalloy during heat treatment processing

Simulation of the Effect of Contact Area Loss in All-Solid-State Li-Ion Batteries

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