The Devil is in the Defects: Electronic Conductivity in Solid Electrolytes

Gorai, Prashun; Famprikis, Theodosios; Singh, Gill Baltej; Stevanović, Vladan; Canepa, Pieremanuele

doi:10.26434/chemrxiv.13167197

Cited by 10 publications

(10 citation statements)

References 83 publications

(171 reference statements)

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“…For this specific case the energy required for Na + migration should also include the formation energy of Na vacancy, which we computed using the method of Ref. 79. We found that the Na vacancy formation energy in NaZr 2 (PO 4 ) 3 is ~474 meV, which we added to our model.…”

Section: Sodium Migration Barriers From Density Functional Theorymentioning

confidence: 99%

Fundamental investigations on the sodium-ion transport properties of mixed polyanion solid-state battery electrolytes

et al. 2022

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Lithium and sodium (Na) mixed polyanion solid electrolytes for all-solid-state batteries display some of the highest ionic conductivities reported to date. However, the effect of polyanion mixing on the ion-transport properties is still not fully understood. Here, we focus on Na1+xZr2SixP3−xO12 (0 ≤ x ≤ 3) NASICON electrolyte to elucidate the role of polyanion mixing on the Na-ion transport properties. Although NASICON is a widely investigated system, transport properties derived from experiments or theory vary by orders of magnitude. We use more than 2000 distinct ab initio-based kinetic Monte Carlo simulations to map the compositional space of NASICON over various time ranges, spatial resolutions and temperatures. Via electrochemical impedance spectroscopy measurements on samples with different sodium content, we find that the highest ionic conductivity (i.e., about 0.165 S cm–1 at 473 K) is experimentally achieved in Na3.4Zr2Si2.4P0.6O12, in line with simulations (i.e., about 0.170 S cm–1 at 473 K). The theoretical studies indicate that doped NASICON compounds (especially those with a silicon content x ≥ 2.4) can improve the Na-ion mobility compared to undoped NASICON compositions.

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Section: Sodium Migration Barriers From Density Functional Theorymentioning

confidence: 99%

Fundamental investigations on the sodium-ion transport properties of mixed polyanion solid-state battery electrolytes

et al. 2022

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“…As the defect concentration decreases, Li + transport is hindered and the ionic conductivity of the sample decreases. These findings emphasize the importance of defects in promoting long-range Li + conduction in halide-type SEs 53 and suggest that the conduction properties in these structures are enhanced by high defect concentrations associated with metastable states.…”

Section: Introductionmentioning

confidence: 60%

Stacking Faults Assist Lithium-Ion Conduction in a Halide-Based Superionic Conductor

et al. 2022

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In the pursuit of urgently needed, energy dense solid-state batteries for electric vehicle and portable electronics applications, halide solid electrolytes offer a promising path forward with exceptional compatibility against high-voltage oxide electrodes, tunable ionic conductivities, and facile processing. For this family of compounds, synthesis protocols strongly affect cation site disorder and modulate Li + mobility. In this work, we reveal the presence of a high concentration of stacking faults in the superionic conductor Li 3 YCl 6 and demonstrate a method of controlling its Li + conductivity by tuning the defect concentration with synthesis and heat treatments at select temperatures. Leveraging complementary insights from variable temperature synchrotron X-ray diffraction, neutron diffraction, cryogenic transmission electron microscopy, solid-state nuclear magnetic resonance, density functional theory, and electrochemical impedance spectroscopy, we identify the nature of planar defects and the role of nonstoichiometry in lowering Li + migration barriers and increasing Li site connectivity in mechanochemically synthesized Li 3 YCl 6 . We harness paramagnetic relaxation enhancement to enable 89 Y solid-state NMR and directly contrast the Y cation site disorder resulting from different preparation methods, demonstrating a potent tool for other researchers studying Y-containing compositions. With heat treatments at temperatures as low as 333 K (60 °C), we decrease the concentration of planar defects, demonstrating a simple method for tuning the Li + conductivity. Findings from this work are expected to be generalizable to other halide solid electrolyte candidates and provide an improved understanding of defect-enabled Li + conduction in this class of Li-ion conductors.

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“…For this specific case the energy required for Na + migration should also include the formation energy of Na vacancy, which we computed using the method of Ref. 79 . We found that the Na vacancy formation energy in NaZr2(PO4)3 is ~ 474 meV, which we added in our model (see SI).…”

Section: Sodium Migration Barriers From Density Functional Theorymentioning

confidence: 99%

Theoretical and Experimental Studies of ion Transport in Mixed Polyanion Solid Electrolytes

Deng

Mishra

Mahayoni

et al. 2021

Preprint

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Lithium and sodium (Na) mixed polyanion solid electrolytes for all-solid-state batteries display some of the highest ionic conductivities reported to date. However, the effect of polyanion mixing on ion transport properties is still debated. Here, we focus on Na1+xZr2SixP3-xO12 (0 ≤ x ≤ 3) NASICON electrolyte to elucidate the role of polyanion mixing on Na-transport properties. Although there is a large body of data available on this NASICON system, transport properties extracted from experiments or theory vary by orders of magnitude, signifying the need to bridge the gap between different studies. Here, more than 2,000 distinct ab initio-based kinetic Monte Carlo simulations have been used to map the statistically vast compositional space of NASICON over an unprecedented time range and spatial resolution and across a range of temperatures. We performed impedance spectroscopy of samples with varying Na compositions revealing that the highest ionic conductivity (~ 0.1 S cm–1) is achieved in Na3.4Zr2Si2.4P0.6O12, in line with our predictions (~0.2 S cm–1). Our predictions indicate that suitably doped NASICON compositions, especially with high silicon content, can achieve high Na+ mobilities. Our findings are relevant for the optimization of mixed polyanion solid electrolytes and electrodes, including sulfide-based polyanion frameworks, which are known for their superior ionic conductivities.

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The Devil is in the Defects: Electronic Conductivity in Solid Electrolytes

Cited by 10 publications

References 83 publications

Fundamental investigations on the sodium-ion transport properties of mixed polyanion solid-state battery electrolytes

Fundamental investigations on the sodium-ion transport properties of mixed polyanion solid-state battery electrolytes

Stacking Faults Assist Lithium-Ion Conduction in a Halide-Based Superionic Conductor

Theoretical and Experimental Studies of ion Transport in Mixed Polyanion Solid Electrolytes

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