Design rules for liquid crystalline electrolytes for enabling dendrite-free lithium metal batteries

Ahmad, Zeeshan; Hong, Zijian; Viswanathan, Venkatasubramanian

doi:10.1073/pnas.2008841117

Cited by 40 publications

(38 citation statements)

References 102 publications

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“…70,71 A similar analysis could be performed for amorphous interfaces including organic components and provide insights into their effect on additional driving forces involved in the kinetics. 72 Amorphous regions generated in the multiphase SEI might disrupt Li-ion diffusion pathways and result in a lower ionic conductivity than the single-phase SEI. 68 A highly heterogeneous SEI might also result in varying current densities in different regions of the electrode−electrolyte interface, potentially leading to dendrite growth in Li metal batteries.…”

Section: ■ Summary and Conclusionmentioning

confidence: 99%

Interfaces in Solid Electrolyte Interphase: Implications for Lithium-Ion Batteries

et al. 2021

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The existence of passivating layers at the interfaces is a major factor enabling modern lithium-ion (Li-ion) batteries. The properties of the passivation layers determine the cycle life, performance, and safety of batteries. One critical passivation layer is the solid electrolyte interphase (SEI), a heterogeneous multicomponent film formed due to the decomposition of the electrolyte at the surface of the anode. The multicomponent nature is critical for its functioning as the interfaces between these components play a critical role in determining performance and safety. In this work, we use first-principles simulations to investigate the thermodynamic, kinetic, and electronic properties of the interface between lithium fluoride (LiF) and lithium carbonate (Li2CO3), two common SEI components present in Li-ion batteries with organic liquid electrolytes. We construct a coherent interface between these components that restricts the strain in each of them to below 3%. We find that the interfacial structure has a formation energy of the Frenkel defect higher than bulk calculations and similar to pristine Li2CO3, generating Li vacancies in LiF and Li interstitials in Li2CO3 responsible for transport. On the other hand, the Li interstitial hopping barrier is reduced from 0.3 eV in bulk Li2CO3 to 0.10 or 0.22 eV in the interfacial structure considered, demonstrating the favorable role of the interface. Controlling these two effects in a heterogeneous SEI is crucial for maintaining fast ion transport in the SEI. We further perform Car–Parrinello molecular dynamics simulations to explore Li-ion conduction in our interfacial structure, which reveal an enhanced Li-ion diffusion in the vicinity of the interface. Understanding the interfacial properties of the multiphase SEI represents an important frontier to enable next-generation batteries.

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Section: ■ Summary and Conclusionmentioning

confidence: 99%

Interfaces in Solid Electrolyte Interphase: Implications for Lithium-Ion Batteries

et al. 2021

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“…For example, a stress of 10 MPa, which is on the higher end of values for the yield stress of Li, contributes an overpotential of ∼ V Li σ/F = 1.3 meV. Therefore, other phenomena to manipulate local current density like piezoelectric response [149] and orientational ordering [40] at the microscale may provide additional driving forces to dynamically stabilize Li plating and stripping.…”

Section: Discussionmentioning

confidence: 99%

“…Various values of δ mech can be found in literature which correspond to different ways the mechanical part of free energy can affect the barrier. A common approach in literature is to assume δ mech M = 0 and δ mech M + = 1 [36,37,38,39,40], which implies that the barrier is only affected by the mechanical part of the free energy of the electrolyte. Setting both δ mech M and δ mech M + to zero implies the barrier is unaffected my mechanics.…”

Section: Kineticsmentioning

confidence: 99%

Chemomechanics: friend or foe of the "AND problem" of solid-state batteries?

Ahmad,

Venturi,

Sripad

et al. 2021

Preprint

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Solid state electrolytes are widely considered as the enabler of lithium metal anodes for safe, durable and high energy density rechargeable lithium ion batteries. Despite the promise, failure mechanisms associated with solid state batteries are not well-established, largely due to limited understanding of the chemomechanical factors governing them. We focus on the recent developments in understanding the solid state aspects including the effects of mechanical stresses, constitutive relations, fracture, void formation and outline the gaps in literature. We also provide an overview of the manufacturing and processing of solid state batteries in relation to chemomechanics. The gaps identified provides concrete directions towards the rational design and development of failure resistant solid state batteries.

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“…Most of the organic-based and water-based electrolytes fail in one or more of these realms . Gel electrolytes could be a good alternative to solution-based electrolytes if their conductivity issues could be resolved. − Liquid crystalline electrolytes (LCEs) have also been widely investigated in the literature as gel electrolytes. − The liquid crystalline gel electrolytes are in general in two different forms, thermotropic and lyotropic liquid crystalline (LLC), − such as salt/surfactant LLC mesophases. − LCEs have been employed as gel electrolytes in many ways − such as optical modulation of graphene, effectively switching electrochromic devices, and dye-sensitized solar cells.…”

Section: Introductionmentioning

confidence: 99%

Role of Water in the Lyotropic Liquid Crystalline Mesophase of Lithium Salts and Non-ionic Surfactants

et al. 2021

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The lyotropic liquid crystalline (LLC) mesophase forms upon evaporation of water from aqueous solutions of LiX salts (X is Cl − , Br − , NO 3 − , or SCN − ) and a surfactant [C 12 H 25 (OCH 2 CH 2 ) 10 OH, abbreviated as C 12 E 10 ]. The LiX/ C 12 E 10 /H 2 O aqueous solutions have been monitored (during evaporation of their excess water to obtain stable LLC mesophases) by gravimetric, spectroscopic, and conductivity measurements to elucidate the role of water in these mesophases. The water/salt molar ratio in stable mesophases changes from 1.5 to 8.0, depending on the counteranion of the salt and the ambient humidity of the laboratory. The LiX/C 12 E 10 /H 2 O LLC mesophases lose water at lower humidity levels and absorb water at higher humidity levels. The LiCl-containing mesophase holds as few as four structural water molecules per LiCl, whereas the LiNO 3 mesophase holds 1.5 waters per salt (least among those assessed). This ratio strongly depends on the atmospheric humidity level; the water/LiX mole ratio increases by 0.08 ± 0.01 H 2 O in the LLC mesophases per percent humidity unit. Surprisingly, the LLC mesophases are stable (no salt leaching) in broad humidity (10−85%) and salt/surfactant mole ratio (2−10 LiX/C 12 E 10 ) ranges. Attenuated total reflectance Fourier transform infrared spectroscopic data show that the water molecules in the mesophase interact with salt species more strongly in the LiCl mesophase and more weakly in the case of the nitrate ion, which is evident by the shift of the O−H stretching band of water. The O−H stretching peak position in the mesophases decreases in the order ν LiCl > ν LiBr > ν LiSCN > ν LiNO 3 and accords well with the H 2 O/LiX mole ratio. The conductivity of the LLC mesophase also responds to the amount of water as well as the nature of the counteranion (X − ). The conductivity decreases in the order σ LiCl > σ LiBr > σ LiNO 3 > σ LiSCN at low salt mole ratios and in the order σ LiBr > σ LiCl > σ LiNO 3 > σ LiSCN at higher ratios due to structural changes in the mesophase.

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Design rules for liquid crystalline electrolytes for enabling dendrite-free lithium metal batteries

Cited by 40 publications

References 102 publications

Interfaces in Solid Electrolyte Interphase: Implications for Lithium-Ion Batteries

Interfaces in Solid Electrolyte Interphase: Implications for Lithium-Ion Batteries

Chemomechanics: friend or foe of the "AND problem" of solid-state batteries?

Role of Water in the Lyotropic Liquid Crystalline Mesophase of Lithium Salts and Non-ionic Surfactants

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