Origin of fast ion diffusion in super-ionic conductors

He, Xingfeng; Zhu, Yizhou; Mo, Yifei

doi:10.1038/ncomms15893

Cited by 684 publications

(764 citation statements)

References 43 publications

(58 reference statements)

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“…[47] Our work proves this from the experimental view for the first, to the best of our knowledge. From our Rietveld refinement results (Tables S6-S11, Supporting Information), the introduced Na + -ions mostly occupy Na1 and Na5 sites (higher energy sites compared to the other three Na sites).…”

Section: Activating More Correlated Migration By Increasing the Na + supporting

confidence: 72%

“…Our previous work [43,44] and that of some others [45][46][47] verified that correlated jumps lead to lower energy barriers and higher ion conductivity in some fast ion conductors, for example, Li 3 OX (X = Cl, Br), [45] doped Li 3 PO 4 , [46] and Li 7 La 3 Zr 2 O 12 (LLZO). Our previous work [43,44] and that of some others [45][46][47] verified that correlated jumps lead to lower energy barriers and higher ion conductivity in some fast ion conductors, for example, Li 3 OX (X = Cl, Br), [45] doped Li 3 PO 4 , [46] and Li 7 La 3 Zr 2 O 12 (LLZO).…”

Section: Na + -Ion Dynamics In Nasicon Materialsmentioning

confidence: 55%

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Correlated Migration Invokes Higher Na⁺‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

Zhang

Zou

Kaup

et al. 2019

Advanced Energy Materials

190

223

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Na super ion conductor (NaSICON), Na 1+n Zr 2 Si n P 3-n O 12 is considered one of the most promising solid electrolytes; however, the underlying mechanism governing ion transport is still not fully understood. Here, the existence of a previously unreported Na5 site in monoclinic Na 3 Zr 2 Si 2 PO 12 is unveiled. It is revealed that Na + -ions tend to migrate in a correlated mechanism, as suggested by a much lower energy barrier compared to the single-ion migration barrier. Furthermore, computational work uncovers the origin of the improved conductivity in the NaSICON structure, that is, the enhanced correlated migration induced by increasing the Na + -ion concentration. Systematic impedance studies on doped NaSICON materials bolster this finding. Significant improvements in both the bulk and total ion conductivity (e.g., σ bulk = 4.0 mS cm −1 , σ total = 2.4 mS cm −1 at 25 °C) are achieved by increasing the Na content from 3.0 to 3.30-3.55 mol formula unit −1 . These improvements stem from the enhanced correlated migration invoked by the increased Coulombic repulsions when more Na + -ions populate the structure rather than solely from the increased mobile ion carrier concentration. The studies also verify a strategy to enhance ion conductivity, namely, pushing the cations into high energy sites to therefore lower the energy barrier for cation migration.

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Section: Activating More Correlated Migration By Increasing the Na + supporting

confidence: 72%

Section: Na + -Ion Dynamics In Nasicon Materialsmentioning

confidence: 55%

Correlated Migration Invokes Higher Na⁺‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

Zhang

Zou

Kaup

et al. 2019

Advanced Energy Materials

190

223

View full text Add to dashboard Cite

show abstract

“…The ever increasing requirements for better capacity, safety, cycle performance, and durability led to solid-state lithium batteries with the research focusing mainly on the electrolyte and cathode materials 1–12 . In that respect, considerable effort has been devoted to identify alternative cathode materials for rechargeable lithium ion batteries in order to provide high energy density for large scale applications particularly in electric vehicles and to replace conventional positive electrode material LiCoO 2 due to its issues associated with cost and safety 13 .…”

Section: Introductionmentioning

confidence: 99%

Lithium diffusion in Li5FeO4

Kuganathan

Iyngaran

Chroneos

2018

Sci Rep

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The anti-fluorite type Li5FeO4 has attracted significant interest as a potential cathode material for Li ion batteries due to its high Li content and electrochemical performance. Atomic scale simulation techniques have been employed to study the defects and Li ion migration in Li5FeO4. The calculations suggest that the most favorable intrinsic defect type is calculated to be the cation anti-site defect, in which Li+ and Fe3+ ions exchange positions. Li Frenkel is also found to be lower in this material (0.85 eV/defect). Long range lithium diffusion paths were constructed in Li5FeO4 and it is confirmed that the lower migration paths are three dimensional with the lowest activation energy of migration at 0.45 eV. Here we show that doping by Si on the Fe site is energetically favourable and an efficient way to introduce a high concentration of lithium vacancies. The introduction of Si increases the migration energy barrier of Li in the vicinity of the dopant to 0.59 eV. Nevertheless, the introduction of Si is positive for the diffusivity as the migration energy barrier increase is lower less than that of the lithium Frenkel process, therefore the activation energy of Li diffusion.

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“…Understanding their roots, preferably with the help of theory 31,32 , is also crucial and would enable us to safely control their dynamic properties. Yet, for many materials, however, there is still no complete picture available consistently describing the interrelation of the elementary steps of hopping with long-range ion transport.…”

Section: Introductionmentioning

confidence: 99%

Fast Na ion transport triggered by rapid ion exchange on local length scales

Lunghammer

Prutsch

Breuer

et al. 2018

Sci Rep

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The realization of green and economically friendly energy storage systems needs materials with outstanding properties. Future batteries based on Na as an abundant element take advantage of non-flammable ceramic electrolytes with very high conductivities. Na3Zr2(SiO4)2PO4-type superionic conductors are expected to pave the way for inherently safe and sustainable all-solid-state batteries. So far, only little information has been extracted from spectroscopic measurements to clarify the origins of fast ionic hopping on the atomic length scale. Here we combined broadband conductivity spectroscopy and nuclear magnetic resonance (NMR) relaxation to study Na ion dynamics from the µm to the angstrom length scale. Spin-lattice relaxation NMR revealed a very fast Na ion exchange process in Na3.4Sc0.4Zr1.6(SiO4)2PO4 that is characterized by an unprecedentedly high self-diffusion coefficient of 9 × 10−12 m2s−1 at −10 °C. Thus, well below ambient temperature the Na ions have access to elementary diffusion processes with a mean residence time τNMR of only 2 ns. The underlying asymmetric diffusion-induced NMR rate peak and the corresponding conductivity isotherms measured in the MHz range reveal correlated ionic motion. Obviously, local but extremely rapid Na+ jumps, involving especially the transition sites in Sc-NZSP, trigger long-range ion transport and push ionic conductivity up to 2 mS/cm at room temperature.

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Origin of fast ion diffusion in super-ionic conductors

Cited by 684 publications

References 43 publications

Correlated Migration Invokes Higher Na⁺‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

Correlated Migration Invokes Higher Na⁺‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

Lithium diffusion in Li5FeO4

Fast Na ion transport triggered by rapid ion exchange on local length scales

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Origin of fast ion diffusion in super-ionic conductors

Cited by 684 publications

References 43 publications

Correlated Migration Invokes Higher Na+‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

Correlated Migration Invokes Higher Na+‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

Lithium diffusion in Li5FeO4

Fast Na ion transport triggered by rapid ion exchange on local length scales

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Correlated Migration Invokes Higher Na⁺‐Ion Conductivity in NaSICON‐Type Solid Electrolytes

Correlated Migration Invokes Higher Na⁺‐Ion Conductivity in NaSICON‐Type Solid Electrolytes