Evidence for a Solid-Electrolyte Inductive Effect in Superionic Conductors

Identifying and optimizing highly-conducting lithium-ion solid electrolytes is a critical step towards the realization of commercial all–solid-state lithium-ion batteries. Strategies to enhance ionic conductivities in solid electrolytes typically focus on the effects of modifying their crystal structures or of tuning mobile-ion stoichiometries. A less-explored approach is to modulate the chemical-bonding interactions within a material to promote fast lithium-ion diffusion. Recently, the idea of a solid-electrolyte inductive effect was proposed, whereby changes in bonding within the solid-electrolyte host-framework modify the potential-energy landscape for the mobile ions, resulting in an enhanced ionic conductivity. This concept has since been invoked to explain anomalous conductivity trends in a number of solid electrolytes. Direct evidence for a solid-electrolyte inductive effect, however, is lacking—in part because of the challenge of quantifying changes in local bonding interactions within a solid-electrolyte host-framework. <a></a><a>Here, we consider the evidence for a solid-electrolyte inductive effect in the archetypal superionic lithium-ion conductor Li10Ge1−xSnxP2S12, using Rietveld refinements against high-resolution temperature-dependent neutron-diffraction data, Raman spectroscopy, and density functional theory calculations.</a> Substituting Ge for Sn weakens the {Ge,Sn}–S bonding interactions and increases the charge-density associated with the S2- ions. This charge redistribution modifies the Li+ substructure causing Li+ ions to bind more strongly to the host-framework S anions; which in turn modulates the Li-ion potential-energy surface, increasing local barriers for Li-ion diffusion. Each of these effects is consistent with the predictions of the solid-electrolyte inductive effect model. Density functional theory calculations further predict that this inductive effect occurs even in the absence of changes to the host-framework geometry due to Ge → Sn substitution. These results provide direct evidence in support of a measurable solid-electrolyte inductive effect and demonstrate its application as a practical strategy for tuning ionic conductivities in superionic lithium-ion conductors.

Download Full-text

Lithium-ion conductivity in Li6Y(BO3)3: a thermally and electrochemically robust solid electrolyte

Journal of Materials Chemistry A ◽

10.1039/c5ta09436d ◽

2016 ◽

Vol 4 (18) ◽

pp. 6972-6979 ◽

Cited By ~ 7

Author(s):

Beatriz Lopez-Bermudez ◽

Wolfgang G. Zeier ◽

Shiliang Zhou ◽

Anna J. Lehner ◽

Jerry Hu ◽

...

Keyword(s):

Energy Storage ◽

Solid Electrolyte ◽

Solid Electrolytes ◽

Lithium Ion ◽

Ion Conductivity ◽

Ion Diffusion ◽

New Energy ◽

Li Ion ◽

Lithium Ion Conductivity ◽

Storage Technologies

The development of new frameworks for solid electrolytes exhibiting fast Li-ion diffusion is critical for enabling new energy storage technologies.

Download Full-text

MX (M = Ge, Sn; X = S, Se) sheets: theoretical prediction of new promising electrode materials for Li ion batteries

Journal of Materials Chemistry A ◽

10.1039/c6ta03076a ◽

2016 ◽

Vol 4 (28) ◽

pp. 10906-10913 ◽

Cited By ~ 54

Author(s):

Yungang Zhou

Keyword(s):

Density Functional Theory ◽

High Performance ◽

Density Functional ◽

Electrode Materials ◽

Lithium Ion ◽

Density Functional Theory Calculations ◽

Two Dimensional ◽

Li Ion Batteries ◽

Functional Theory ◽

Li Ion

In this work, via density functional theory calculations, we explored the interaction of Li with recently synthesized two-dimensional structures, MX (M = Ge, Sn; X = S, Se) sheets, for application in high-performance lithium ion batteries.

Download Full-text

Na-ion diffusion in a NASICON-type solid electrolyte: a density functional study

Physical Chemistry Chemical Physics ◽

10.1039/c6cp05164b ◽

2016 ◽

Vol 18 (39) ◽

pp. 27226-27231 ◽

Cited By ~ 13

Author(s):

Kieu My Bui ◽

Van An Dinh ◽

Susumu Okada ◽

Takahisa Ohno

Keyword(s):

Density Functional Theory ◽

Solid Electrolyte ◽

Electronic Structures ◽

Density Functional ◽

Diffusion Mechanism ◽

Functional Study ◽

Ion Diffusion ◽

Functional Theory ◽

Density Functional Study ◽

Nasicon Type

Based on density functional theory, we have systematically studied the crystal and electronic structures, and the diffusion mechanism of the NASICON-type solid electrolyte Na3Zr2Si2PO12.

Download Full-text

Native Defects and their Doping Response in the Lithium Solid Electrolyte Li7La3Zr2O12

10.26434/chemrxiv.9031346.v2 ◽

2019 ◽

Author(s):

Alex Squires ◽

David Scanlon ◽

Benjamin Morgan

Keyword(s):

Density Functional ◽

Ionic Conductivities ◽

Density Functional Theory Calculations ◽

Defect Chemistry ◽

Functional Theory ◽

Native Defects ◽

Synthesis Conditions ◽

Reducing Conditions ◽

Solid State Batteries ◽

Hybrid Density Functional

The Li-stuffed garnets LixM2M3′O12 are promising Li-ion solid electrolytes with potential use in solid-state batteries. One strategy for optimising ionic conductivities in these materials is to tune lithium stoichiometries through aliovalent doping, which is often assumed to produce proportionate numbers of charge compensating Li vacancies. The native defect chemistry of the Li-stuffed garnets, and their response to doping, however, are not well understood, and it is unknown to what degree a simple vacancy-compensation model is valid. Here, we report hybrid density-functional–theory calculations of a broad range of native defects in the prototypical Li-garnet Li7La3Zr2O12. We calculate equilibrium defect concentrations as a function of synthesis conditions, and model the response of these defect populations to extrinsic doping. We predict a rich defect chemistry that includes Li and O vacancies and interstitials, and significant numbers of cation-antisite defects. Under reducing conditions, O vacancies act as colour-centres by trapping electrons. We find that supervalent (donor) doping does not produce charge compensating Li vacancies under all synthesis conditions; under Li-rich / Zr-poor conditions the dominant compensating defects are LiZr antisites, and Li stoichiometries strongly deviate from those predicted by simple “vacancy compensation” models.

Download Full-text

Defects, Diffusion, and Dopants in Li2Ti6O13: Atomistic Simulation Study

Materials ◽

10.3390/ma12182851 ◽

2019 ◽

Vol 12 (18) ◽

pp. 2851 ◽

Cited By ~ 5

Author(s):

Navaratnarajah Kuganathan ◽

Sashikesh Ganeshalingam ◽

Alexander Chroneos

Keyword(s):

Electronic Structures ◽

Atomistic Simulation ◽

Density Functional ◽

High Capacity ◽

Ion Diffusion ◽

Functional Theory ◽

Energy Process ◽

Defect Energy ◽

Li Ion ◽

Isovalent Dopant

In this study, force field-based simulations are employed to examine the defects in Li-ion diffusion pathways together with activation energies and a solution of dopants in Li2Ti6O13. The lowest defect energy process is found to be the Li Frenkel (0.66 eV/defect), inferring that this defect process is most likely to occur. This study further identifies that cation exchange (Li–Ti) disorder is the second lowest defect energy process. Long-range diffusion of Li-ion is observed in the bc-plane with activation energy of 0.25 eV, inferring that Li ions move fast in this material. The most promising trivalent dopant at the Ti site is Co3+, which would create more Li interstitials in the lattice required for high capacity. The favorable isovalent dopant is the Ge4+ at the Ti site, which may alter the mechanical property of this material. The electronic structures of the favorable dopants are analyzed using density functional theory (DFT) calculations.

Download Full-text

Metallic FeSe monolayer as an anode material for Li and non-Li ion batteries: a DFT study

Physical Chemistry Chemical Physics ◽

10.1039/d0cp00967a ◽

2020 ◽

Vol 22 (16) ◽

pp. 8902-8912 ◽

Cited By ~ 2

Author(s):

Xiaodong Lv ◽

Fengyu Li ◽

Jian Gong ◽

Jinxing Gu ◽

Shiru Lin ◽

...

Keyword(s):

Density Functional Theory ◽

Electrochemical Performance ◽

Lithium Ion Batteries ◽

Anode Material ◽

Density Functional ◽

Lithium Ion ◽

Li Ion Batteries ◽

Functional Theory ◽

Li Ion ◽

Density Functional Theory Computations

By means of density functional theory computations, we explored the electrochemical performance of an FeSe monolayer as an anode material for lithium and non-lithium ion batteries (LIBs and NLIBs).

Download Full-text

Spin polarization in the phase diagram of a Li–Fe–S system

Scientific Reports ◽

10.1038/s41598-019-56244-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Tsuyoshi Takami ◽

Tomonari Takeuchi ◽

Toshiharu Fukunaga

Keyword(s):

Spin Polarization ◽

Density Functional ◽

Inorganic Compounds ◽

Density Functional Theory Calculations ◽

Phase Changes ◽

Electrochemical Technique ◽

Functional Theory ◽

Li Ion ◽

Fe Ions ◽

Li Content

AbstractDivalent and trivalent states of Fe ions are known to be stable in inorganic compounds. We focus a novel LixFeS5 cathode, in which the Li content (x) changes from 2 to 10 by an electrochemical technique. As x increases from 2, a Pauli paramagnetic conductive Li2FeS5 phase changes into a superparamagnetic insulating Li10FeS5 phase. Density functional theory calculations suggest that Fe+ ions in a high-x phase are responsible for ferromagnetic spin polarization. Reaching the monovalent Fe ion is significant for understanding microscopic chemistry behind operation as Li-ion batteries and the original physical properties resulting from the unique local structure.

Download Full-text

Electrical structures, magnetic polaron and lithium ion dynamics in three transition metal doped LiFe1−xMxPO4 (M = Mn, Co and La) cathode material for Li ion batteries from density functional theory study

Solid State Ionics ◽

10.1016/j.ssi.2016.06.009 ◽

2016 ◽

Vol 294 ◽

pp. 73-81 ◽

Cited By ~ 11

Author(s):

Yi Xiao ◽

Fu Chun Zhang ◽

Jeong In Han

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Lithium Ion ◽

Magnetic Polaron ◽

Ion Dynamics ◽

Li Ion Batteries ◽

Density Functional Theory Study ◽

Functional Theory ◽

Li Ion ◽

Metal Doped

Download Full-text

Native Defects and their Doping Response in the Lithium Solid Electrolyte Li7La3Zr2O12

10.26434/chemrxiv.9031346.v1 ◽

2019 ◽

Author(s):

Alex Squires ◽

David Scanlon ◽

Benjamin Morgan

Keyword(s):

Density Functional ◽

Ionic Conductivities ◽

Density Functional Theory Calculations ◽

Defect Chemistry ◽

Functional Theory ◽

Native Defects ◽

Synthesis Conditions ◽

Reducing Conditions ◽

Solid State Batteries ◽

Hybrid Density Functional

The Li-stuffed garnets LixM2M3′O12 are promising Li-ion solid electrolytes with potential use in solid-state batteries. One strategy for optimising ionic conductivities in these materials is to tune lithium stoichiometries through aliovalent doping, which is often assumed to produce proportionate numbers of charge compensating Li vacancies. The native defect chemistry of the Li-stuffed garnets, and their response to doping, however, are not well understood, and it is unknown to what degree a simple vacancy-compensation model is valid. Here, we report hybrid density-functional–theory calculations of a broad range of native defects in the prototypical Li-garnet Li7La3Zr2O12. We calculate equilibrium defect concentrations as a function of synthesis conditions, and model the response of these defect populations to extrinsic doping. We predict a rich defect chemistry that includes Li and O vacancies and interstitials, and significant numbers of cation-antisite defects. Under reducing conditions, O vacancies act as colour-centres by trapping electrons. We find that supervalent (donor) doping does not produce charge compensating Li vacancies under all synthesis conditions; under Li-rich / Zr-poor conditions the dominant compensating defects are LiZr antisites, and Li stoichiometries strongly deviate from those predicted by simple “vacancy compensation” models.

Download Full-text