Film strains enhance the reversible cycling of intercalation electrodes

Zhang, Delin; Sheth, Jay; Sheldon, Brian W.; Balakrishna, Ananya Renuka

doi:10.1016/j.jmps.2021.104551

Cited by 10 publications

(7 citation statements)

References 64 publications

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“…This structural transformation is accompanied by an unfolding of the V 2 O 5 layers. On deep discharge of Li x V 2 O 5 (i.e., inserting x > 2 Li ions), the cathode becomes increasingly disordered (or amorphous) and contributes to the structural degradation of the material [48,32].…”

Section: Types Of Structural Transformationmentioning

confidence: 99%

“…In one strategy, called 'staging', researchers diffuse the guest species into select crystallographic channels of the intercalation material (e.g., in graphite systems [50,51]), occupying only a fraction of the intercalation sites and thereby reducing internal stresses in the materials. In other strategies, researchers suppress structural transformations by engineering host materials as nanoparticles, by designing mechanical constraints as epitaxial strains [32] or coherency stressses [52], and by operating intercalation materials within specific voltage windows. While these strategies delay chemo-mechanical degradation of intercalation materials and have improved their lifespans, they do so at the cost of the material's energy storage capacity 3 Further intercalation of lithium leads to the formation of a metastable phase that has been examined as a potential cathode candidate for multivalent ion intercalation [47].…”

Section: Designing Structural Transformationsmentioning

confidence: 99%

“…(d) The polyhedral chains (nanoribbons) in Li x V 2 O 5 unfold and pucker during intercalation resulting in a disordered (or amorphous) phase. Reprinted from [32] with permission from Elsevier.…”

Section: Introductionmentioning

confidence: 99%

“…In another line of research, mechanical constraints such as substrate strains have been used to delay the onset of large structural transformations in thin film electrodes[32].…”

mentioning

confidence: 99%

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Crystallographic design of intercalation materials

Balakrishna¹

2022

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Intercalation materials are promising candidates for reversible energy storage and are, for example, used as lithium-battery electrodes, hydrogen-storage compounds, and electrochromic materials. An important issue preventing the more widespread use of these materials is that they undergo structural transformations (of up to ∼ 10% lattice strains) during intercalation, which expand the material, nucleate microcracks, and, ultimately, lead to material failure. Besides the structural transformation of lattices, the crystallographic texture of the intercalation material plays a key role in governing ion-transport properties, generating phase separation microstructures, and elastically interacting with crystal defects.In this review, I provide an overview of how the structural transformation of lattices, phase transformation microstructures, and crystallographic defects affect the chemo-mechanical properties of intercalation materials. In each section, I identify the key challenges and opportunities to crystallographically design intercalation compounds to improve their properties and lifespans. I predominantly cite examples from the literature of intercalation cathodes used in rechargeable batteries, however, the identified challenges and opportunities are transferable to a broader range of intercalation compounds.

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Section: Types Of Structural Transformationmentioning

confidence: 99%

Section: Designing Structural Transformationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In another line of research, mechanical constraints such as substrate strains have been used to delay the onset of large structural transformations in thin film electrodes[32].…”

mentioning

confidence: 99%

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Crystallographic design of intercalation materials

Balakrishna¹

2022

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“…Transition metal oxides such as V 2 O 5 with multiple accessible redox states, a low proclivity for oxygen evolution, and a globally distributed supply chain are of practical interest as intercalation cathodes. − In this and many other intercalation hosts, such as LiFePO 4 , lithiation brings about a series of distortive structural transformations that have substantial implications for stress accumulation and capacity loss. , Much effort has focused on mitigating the deleterious effects of phase transformations through modification of particle geometry, use of mechanical constraints, or altogether avoiding phase-transforming materials. − We demonstrate here an approach for accessing extended solid-solution lithiation regimes based on doping of a phase-transforming electrode to stabilize a structure that bears similarities to the initially lithiated phase. This embodies a “ pre-transformation through doping ” design principle, wherein the thermodynamic penalty associated with the phase transformation is paid during materials synthesis rather than during electrochemical discharge/charge.…”

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confidence: 91%

Doping-Induced Pre-Transformation to Extend Solid-Solution Regimes in Li-Ion Batteries

et al. 2022

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In many intercalation electrodes of Li-ion batteries, lithiation induces distortive structural transformations with substantial implications for stress accumulation, capacity loss, and degraded rate performance. Here, we dope a phase-transforming electrode to stabilize a structure bearing considerable similarities to the initially lithiated phase. In this "pre-transformation" approach, demonstrated based on Mo-doping of V 2 O 5 , the thermodynamic penalty associated with the phase transformation is paid in part during materials' synthesis rather than the charge/discharge of a battery. Mo-doping alters Li−V 2 O 5 thermodynamics to unlock extended solid-solution lithiation regimes with modulated interplanar separations. Specifically, Mo-doping reduces structural distortions during charge/discharge processes, diminishes coherency stresses, and yields a substantially modified intercalation phase diagram. Operando synchrotron X-ray diffraction and chemical lithiation results in conjunction with phase-field modeling demonstrate the promise of doping-induced structural distortions to entirely alter phase evolution and improve electrochemistry−mechanics coupling in phase-transforming cathodes.

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