scholarly journals Ionic Conductivity of Nanocrystalline and Amorphous Li10GeP2S12: The Detrimental Impact of Local Disorder on Ion Transport

2021 ◽  
Author(s):  
Katharina Hogrefe ◽  
Lukas Schweiger ◽  
Bernhard Gadermaier ◽  
Jennifer L. M. Rupp ◽  
H. Martin R. Wilkening
Keyword(s):  
Ionic Conductivity ◽  
Ion Transport ◽  
Ball Milling ◽  
High Energy ◽  
Magic Angle Spinning ◽  
Coarse Grained ◽  
Magic Angle ◽  
Ion Dynamics ◽  
Li Ion ◽  
Local Disorder

Solid electrolytes with extraordinarily high Li-ionic conductivities are key for high performance all-solid-state batteries. So far, the thiophosphate Li10GeP2S12 (LGPS) belongs to the best Li ion conductors with an ionic conductivity exceeding 10 mS cm–1 at ambient. Recent molecular dynamics simulations performed by Dawson and Islam predict that the ionic conductivity of LGPS can be further enhanced by a factor of three if the crystallite size is reduced to the nanometer regime. A change in local ion coordination, hence local disorder, has been assumed to facilitate Li diffusion in the ab-plane of LGPS. As yet, no experimental evidence exists supporting this fascinating prediction. Here, we synthesized nanocrystalline LGPS by high-energy ball milling, characterized the material structurally and probed the Li+ ion transport parameters. Whereas X-ray powder diffraction and high-resolution 31P and 6Li magic angle spinning nuclear magnetic resonance (NMR) spectroscopy helped us to determine morphological changes and local structures upon milling, broadband conductivity spectroscopy in combination with electric modulus measurements allowed us to precisely follow the changes in Li+ ion dynamics. Surprisingly and against the behavior of other electrolytes, ionic conductivity turned out to decrease with increasing milling time, finally leading to a reduction of σ20°C by almost a factor of 10. This decrease affects both, bulk ion dynamics and total conductivity, which also comprises Li+ transport across grain boundary regions in LGPS. As could be shown by NMR, ball-milling leads to a structurally heterogeneous sample with the nm-sized LGPS crystallites being embedded in an amorphous matrix. This amorphous phase is responsible for the reduced performance of the milled electrolyte. Importantly, careful separation of the amorphous and (nano)crystalline contributions to the overall ionic conductivity revealed that even in the nanocrystalline regions Li+ ion dynamics is slowed down compared to untreated, coarse-grained LGPS. We conclude that defects introduced into the LGPS bulk structure via ball milling have a negative impact on ionic transport. We postulate that such kind of structural disorder is detrimental to fast ion transport in materials whose transport properties rely on crystallographically well-defined diffusion pathways.

Probing the Effect of High Energy Ball Milling on the Structure and Properties of LiNi1/3Mn1/3Co1/3O2 Cathodes for Li-Ion Batteries

2016 ◽  
Vol 13 (3) ◽  
Author(s):  
Malcolm Stein ◽  
Chien-Fan Chen ◽  
Matthew Mullings ◽  
David Jaime ◽  
Audrey Zaleski ◽  
...  
Keyword(s):  
Particle Size ◽  
Electrochemical Performance ◽  
Crystallite Size ◽  
Ball Milling ◽  
Lithium Ion ◽  
High Energy ◽  
Li Ion Batteries ◽  
Structure And Properties ◽  
Transfer Resistance ◽  
Li Ion

Particle size plays an important role in the electrochemical performance of cathodes for lithium-ion (Li-ion) batteries. High energy planetary ball milling of LiNi1/3Mn1/3Co1/3O2 (NMC) cathode materials was investigated as a route to reduce the particle size and improve the electrochemical performance. The effect of ball milling times, milling speeds, and composition on the structure and properties of NMC cathodes was determined. X-ray diffraction analysis showed that ball milling decreased primary particle (crystallite) size by up to 29%, and the crystallite size was correlated with the milling time and milling speed. Using relatively mild milling conditions that provided an intermediate crystallite size, cathodes with higher capacities, improved rate capabilities, and improved capacity retention were obtained within 14 μm-thick electrode configurations. High milling speeds and long milling times not only resulted in smaller crystallite sizes but also lowered electrochemical performance. Beyond reduction in crystallite size, ball milling was found to increase the interfacial charge transfer resistance, lower the electrical conductivity, and produce aggregates that influenced performance. Computations support that electrolyte diffusivity within the cathode and film thickness play a significant role in the electrode performance. This study shows that cathodes with improved performance are obtained through use of mild ball milling conditions and appropriately designed electrodes that optimize the multiple transport phenomena involved in electrochemical charge storage materials.

scholarly journals CP MAS kinetics and impedance spectroscopy studies of local disorder in low-dimensional H-bonded proton-conducting materials

2019 ◽  
Vol 59 (3) ◽  
Author(s):  
Laurynas Dagys ◽  
Sergejus Balčiūnas ◽  
Jûras Banys ◽  
Feliksas Kuliešius ◽  
Vladimir Chizhik ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Spin Diffusion ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Coupling Constant ◽  
Spin Lattice ◽  
Local Disorder

The 1H–13C cross-polarization magic angle spinning (CP MAS) kinetics was studied in poly(vinyl phosphonic acid) (pVPA), i.e. material with high degrees of freedom of proton motion along H-bonded chains. It has been shown that the CP kinetic data for the adjacent 1H–13C spin pairs can be described in the frame of the isotropic spin-diffusion approach. The rates of spin diffusion and spin-lattice relaxation as well as the parameters accounting for spin coupling and the effective size of spin clusters have been determined. The local order parameter S ≈ 0.63±0.02, determined as the ratio of the measured dipolar 1H–13C coupling constant and the calculated static dipolar coupling constant, is significantly lower than the values deduced for related sites in other polymers and in series of amino acids. This means that the local disorder of the C–H bonds in pVPA is between those for rather rigid C–H bond configurations having S = 0.8–1.0 and highly disordered –CH3 groups (S ~ 0.4). This effect can be attributed to the presence of the proton transfer path where proton motion is easy to activate. The activation energy for the proton motion Ea = 59±7 kJ/mol was determined from the impedance spectroscopy data analysing the temperature and frequency dependences of the complex dielectric permittivity of pVPA. The rates of proton spin-lattice relaxation and spin diffusion are of the same order and both run in the time scale of milliseconds.

scholarly journals Order vs. disorder—a huge increase in ionic conductivity of nanocrystalline LiAlO2 embedded in an amorphous-like matrix of lithium aluminate

2014 ◽  
Vol 2 (47) ◽  
pp. 20295-20306 ◽  
Author(s):  
D. Wohlmuth ◽  
V. Epp ◽  
P. Bottke ◽  
I. Hanzu ◽  
B. Bitschnau ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Ion Conductivity ◽  
Lithium Aluminate ◽  
The Poor ◽  
Energy Ball

The poor ion conductivity of LiAlO2 can be drastically enhanced via the introduction of defects or amorphisation during high-energy ball milling.

Diffusion and Ionic Conduction in Nanocrystalline Ceramics

2001 ◽  
Vol 676 ◽  
Author(s):  
Paul Heitjans ◽  
Sylvio Indris
Keyword(s):  
Impedance Spectroscopy ◽  
Ball Milling ◽  
Ionic Conduction ◽  
Nmr Relaxation ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Nanocrystalline Ceramics ◽  
Energy Ball ◽  
Li Ion ◽  
Mobile Ions

ABSTRACTDiffusion and ionic conduction in nanocrystalline ceramics, both monophase and composite, was studied by NMR relaxation and NMR lineshape as well as impedance spectroscopy. Measurements were mainly done on Li ion conductors prepared by high-energy ball milling. It was possible to discriminate between mobile ions in the interfacial regions and immobile ions in the grains. In general the diffusivity and conductivity are enhanced in the nanocrystalline monophase system as compared to the microcrystalline one, e. g. by about four orders of magnitude in the case of CaF2. An exception is, e. g., Li2O where the nano- and microcrystalline forms have similar conductivities. However, when the nanocrystalline insulator B2O3 is added to nanocrystalline Li2O the conductivity of the composite increases whereas it decreases in the corresponding microcrystalline system.

SnSb/TiO2/C nanocomposite fabricated by high energy ball milling for high-performance lithium-ion batteries

RSC Advances ◽  
2016 ◽  
Vol 6 (39) ◽  
pp. 32462-32466 ◽  
Author(s):  
Haihua Zhao ◽  
Wen Qi ◽  
Xuan Li ◽  
Hong Zeng ◽  
Ying Wu ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Ball Milling ◽  
High Performance ◽  
High Capacity ◽  
Lithium Ion ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Li Ion Batteries ◽  
Energy Ball ◽  
Li Ion

Alloy anodes for Li-ion batteries (LIBs) have attracted great interest due to their high capacity.

scholarly journals Structure and ion dynamics of mechanosynthesized oxides and fluorides

2017 ◽  
Vol 232 (1-3) ◽  
Author(s):  
Martin Wilkening ◽  
Andre Düvel ◽  
Florian Preishuber-Pflügl ◽  
Klebson da Silva ◽  
Stefan Breuer ◽  
...  
Keyword(s):  
Ion Transport ◽  
Short Review ◽  
High Energy ◽  
Ion Dynamics ◽  
Ball Mills ◽  
Local Structures ◽  
Equilibrium Structures ◽  
Energy Ball ◽  
Metastable Compounds ◽  
Preparation Techniques

AbstractIn many cases, limitations in conventional synthesis routes hamper the accessibility to materials with properties that have been predicted by theory. For instance, metastable compounds with local non-equilibrium structures can hardly be accessed by solid-state preparation techniques often requiring high synthesis temperatures. Also other ways of preparation lead to the thermodynamically stable rather than metastable products. Fortunately, such hurdles can be overcome by mechanochemical synthesis. Mechanical treatment of two or three starting materials in high-energy ball mills enables the synthesis of not only new, metastable compounds but also of nanocrystalline materials with unusual or enhanced properties such as ion transport. In this short review we report about local structures and ion transport of oxides and fluorides mechanochemically prepared by high-energy ball-milling.

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