Young investigator group „Anion and cation conducting electrolytes for solid state batteries“

 

Helmholtz-Institut Münster (HI MS), IEK-12, Forschungszentrum Jülich

The increasing utilization of renewable energy sources and the advance of electromobility demand the provision of suitable energy storage technologies such as lithium-ion batteries, rechargeable oxide batteries and fuel cells.
The central component of this devices is the electrolyte which has to enable high ionic and low electronic conductivity.
Solid electrolytes have the merit of high stability as well as less safety concerns and enable new cell chemistries. In the Young Investigator Group „Anion and cation conducting electrolytes for solid state batteries“ we perform experimental and computational investigations of solid state electrolytes for energy storage devices.

   

Ion migration from first principles

 

We investigate highly conductive solid electrolytes such as Li⁺-conducting Li_1+xAl_xTi_2-x(PO₄)₃, Na⁺-conducting Na_1+xZr₂Si_xP_3-xO₁₂ and O^2--conducting apatites (La_8+x B _2-ySi₆O_{26+3/2x -y}), melilites (La_1+x Sr_1-x Ga₃O_7+0.5) and cerium oxide (CeO₂) by means of density functional theory (DFT)calculations. The structure, local site-energies and migration paths are characterized to obtain a thorough understanding of the materials and predict key properties.

 

From atomistic to macroscopic level

 

Calculations based on density functional theory allow the ab-initio determination of energy barriers and interactions of ionic defects in solids. The ionic conductivity and diffusion coefficients of the material depend on the local energy barriers for the moving ions in various ionic configurations. The transport properties can be simulated by Monte Carlo and molecular dynamics simulations, thereby linking the atomic scale processes to the macroscopic transport phenomena. With the Monte Carlo software „Mocassin“ our team provides a tool to easily predict defect distributions and ionic transport properties based on calculated energy parameters.

Mocassin

 

Surfaces

 

The interface between the solid electrodes and the liquid electrolyte plays a crucial role for the performance of lithium ion batteries. We characterize surfaces (slabs) and their interactions with molecular components of the liquid electrolyte using density functional theory.

 

Synthesis and characterization

 

The synthesis and characterization of solids is important for comparison with simulated data. Synthesis is performed by sol-gel methods or solid state reactions. Samples are characterized by X-ray diffraction and electron microscopy to classify structure and phase purity. Ionic transport properties are investigated by secondary ion mass spectrometry and impedance spectroscopy.

 

Recent Publications:

 

J. Schuett, T.K. Schultze, S. Grieshammer, Oxygen Ion Migration and Conductivity in LaSrGa3O7 Melilites from First Principles, Chem. Mater., 2020, 32, 11, 4442-4450.
DOI: 10.1021/acs.chemmater.9b04599

S. Grieshammer, R. de Souza, Fundamentals of electrical conduction in ceramics, in: Advanced Ceramics for Energy Conversion and Storage, ISBN: 9780081027264

H. R. Arjmandi and S. Grieshammer, Defect formation and migration in Nasicon
Li1+xAlxTi2-x(PO4)3, Phys. Chem. Chem. Phys., 2019, 21, 24232.
DOI: 10.1039/c9cp04792a

F M. Draber, C. Ader, J. Arnold, S. Eisele, S. Grieshammer, S. Yamaguchi, M. Martin, Nanoscale percolation in doped BaZrO3 for high proton mobility, Nature Materials, 2019, 19, 338.
DOI: 10.1038/s41563-019-0561-7

T. Schultze, J. Arnold, S. Grieshammer, „Ab Initio Investigation of Migration Mechanisms in La Apatites“, ACS Appl. Energy Mater. 2019, 2, 4708-4717
DOI: 10.1021/acsaem.9b00226

H. Choi, K. Bae, S. Grieshammer, G. Han, S. Park, J. Kim,D. Jang, J. Koo, J. Son, M. Martin, J. Shim, Surface Tuning of Solid Oxide Fuel Cell Cathode by Atomic Layer Deposition, Advanced energy materials 2018, 8, 1802506
DOI: 10.1002/aenm.201802506

S. Grieshammer , S. Eisele, J. Koettgen, „Modeling Oxygen Ion Migration in the CeO2–ZrO2–Y2O3 Solid Solution”, J. Phys. Chem. C, 2018, 122, 18809–18817. DOI: 10.1021/acs.jpcc.8b04361
S. Grieshammer: „Influence of the lattice constant on defects in cerium oxide“, Phys. Chem. Chem. Phys., 2018, 20, 19792.
DOI: 10.1039/C8CP03677B

A. Rossbach, F. Tietz, S. Grieshammer: „Structural and Transport Properties of Lithium-Conducting NASICON Materials“, J. Power Sources, 2018, 391, 1-9.
DOI: 10.1016/j.jpowsour.2018.04.059

J. Koettgen, S. Grieshammer, P. Hein, B. Grope, M. Nakayama, M. Martin: „Understanding the Ionic Conductivity Maximum in Doped Ceria: Trapping and Blocking“, Phys. Chem. Chem. Phys., 2018, 20, 14291 - 14321.
DOI: 10.1039/c7cp08535d