1,058 research outputs found
Lithium-Ion Batteries: Making Ultrafast High-Capacity Anodes for Lithium-Ion Batteries via Antimony Doping of Nanosized Tin Oxide/Graphene Composites
No full textDina Fattakhova‐Rohlfing and co‐workers describe the fabrication of antimony‐doped tin oxide (ATO)/graphene nanocomposites in article number 1706529. The hybrid structures reveal a very high gravimetric capacity and drastically improved rate performance and cycling stability, making them attractive as ultrafast high‐capacity anodes in lithium‐ion batteries. Cover image designed by Christoph Hohmann, Nanosystems Initiative Munich (NIM)
Electrochemical energy storage: evolutionary and revolutionary concepts
No full textProfessor Dina Fattakhov-Rohlfing and Dr Martin Finsterbusch from the Department of Electrochemical Energy Storage at the Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich, discuss the development of new materials and design for future electrochemical energy storage device
All-inorganic core-shell silica-titania mesoporous colloidal nanoparticles showing orthogonal functionality
No full textColloidal mesoporous silica (CMS) nanoparticles with a thin titania-enriched outer shell showing a spatially resolved functionality were synthesized by a delayed co-condensation approach. The titaniashell can serve as a selective nucleation site for the growth of nanocrystalline anatase clusters. These fully inorganic pure silica-core titania-enriched shell mesoporous nanoparticles show orthogonal functionality, demonstrated through the selective adsorption of a carboxylate-containing ruthenium N3-dye. UV-Vis and fluorescence spectroscopy indicate the strong interaction of the N3-dye with the titania-phase at the outer shell of the CMS nanoparticles. In particular, this interaction and thus the selective functionalization are greatly enhanced when anatase nanocrystallites are nucleated at the titania-enriched shell surface
Optimizing the composite cathode in advanced solid-state batteries through microstructure-resolved simulations
No full textAll-solid-state batteries (ASSBs) are a highly promising technology for future energy storage. Replacing conventional liquid electrolytes with solid electrolytes could increase operational safety and enable the use of lithium metal anodes. These advancements could lead to significantly higher energy and power densities compared to conventional lithium-ion batteries (LIBs). However, the practical performance of ASSBs is still limited by various challenges spanning from the atomistic material to the microscopic electrode and macroscopic cell scale. Advancing ASSB technology requires the development of solid electrolytes with higher ionic conductivities, enhanced stability of solid-solid interfaces, and optimized charge transport in the composite cathode. Addressing these issues is crucial for the successful integration of ASSBs in the future energy systems.
This cumulative thesis focuses on the modeling and microstructure-resolved simulation of ASSBs. Utilizing three-dimensional continuum simulation, it effectively correlates the battery microstructure with its electrochemical performance. The physics-based simulation approach allows for the identification of performance-limiting factors and the development of corresponding optimization strategies. The simulation studies presented in this thesis specifically focus on the composite cathode, which typically consists of interconnected solid electrolyte and active material clusters. Optimizing the underlying microstructure is crucial for developing electrodes with high energy density and rate capability.
Moreover, a better understanding of transport and degradation processes at the electrolyte/active material interface is necessary to increase practical capacities and improve cycling stability. This thesis comprises four peer-reviewed publications that were developed in close collaboration with various experimental and theoretical groups. These papers aim for an improved understanding of ASSBs and demonstrate strategies for optimizing composite cathode design.
In Paper I, we explore the impact of the microstructural properties of the composite cathode on the electrochemical cell performance of ASSBs. Through electrochemical simulations based on virtual microstructures with varying geometric properties, we determine the geometric characteristics of the cathode structures and correlate them to electrochemical performance indicators. This allows us to identify limiting factors assigned to non-optimal cathode design. Our findings highlight the need to enhance ionic transport in high-energy cathodes. A critical role can be attributed to grain boundary resistances in the solid electrolyte, which must be minimized to facilitate high effective ionic conductivities. Requirements for high cell performance are a high cathode density and the optimization of particle sizes, which significantly influence tortuosity, active surface area, and overall grain boundary resistance.
The achievable energy and power densities of ASSBs are limited by the homogeneity of the cathode microstructure. Low effective ionic conductivities pose significant challenges to achieving elevated rate capabilities at the high active material loadings required for increased capacities. Electrode structuring is a promising approach to enhance ionic transport in high-energy cathodes by introducing specific inhomogeneities into the cathode structure. In Paper II, we investigate the potential of cathodes with electrolyte channels and layered cathode structures to enhance ASSB performance. Layered cathodes with an increased solid electrolyte fraction at the separator side and elevated active material fraction at the current collector side of the cathode show promising results. Further progress in processing and optimizing multi-layered cathodes could significantly contribute to improved rate capabilities in high-energy cathodes in future ASSBs.
In Paper III, we focus on the solid electrolyte/cathode active material interface, which is susceptible to chemical, electrochemical, and mechanical degradation during processing and cell operation. Interfacial degradation can lead to the formation of resistive phases, impeding cell performance and cycling stability.
Informed by experimental characterization and atomistic calculations, we investigate the impact of resistive phase formation at the Li7La3Zr2O12 (LLZO) / LiCoO2 (LCO) interface on electrochemical cell performance. We develop a model that allows us to assess the impact of thin resistive films impeding charge transfer at the interface. Our simulation results highlight the importance of increased interface stability during high-temperature sintering by decreasing processing temperatures. Additionally, our studies indicate that the diffusion of aluminum (Al) ions from Al-doped LLZO into LCO plays a significant role in the observed capacity loss during cycling. The formation of an Al-contaminated LCO layer with reduced Li-ion mobility can lead to kinetic limitations and reduced capacities. Thus, mitigating elemental interdiffusion in the composite cathode during cell operation through improved material selection and protective coatings is critical.
Paper IV examines the influence of pressure on the effective ionic conductivity of the thiophosphate t-Li7SiPS8. Optimum pelletizing and stack pressures for maximum conductivities are influenced both by the microstructure of the solid electrolyte and atomistic effects. This study is based on experimental measurements, which are replicated through a combined simulation approach. The microstructure evolution during compression is simulated, which informs our continuum model for determining the effective ionic conductivities. Our results agree well with the experimental data, highlighting the importance of structural and material properties under various mechanical stresses on the samples. The methodology developed in this study can be applied to other material systems, enabling the determination of optimal pelletizing and stack pressures and the identification of favorable microstructural properties to maximize ionic conductivity
“Brick and Mortar” Strategy for the Formation of Highly Crystalline Mesoporous Titania Films from Nanocrystalline Building Blocks
No full textWe present a novel “brick and mortar” strategy for creating highly efficient transparent TiO2 coatings for photocatalytic and photovoltaic applications. Our approach is based on the fusion of preformed titania nanocrystalline “bricks” through surfactant-templated sol−gel titania “mortar”, which acts as a structure-directing matrix and as a chemical glue. The similar chemical composition of both bricks and mortar leads to a striking synergy in the interaction of crystalline and amorphous components, such that crystallization is enhanced upon thermal treatment and highly porous and highly crystalline structures are formed at very mild conditions. Coatings with a broad variety of periodic mesostructures and thicknesses ranging from few nanometers to several micrometers are accessible using the same organic template, and the final structures are tunable by varying the fraction of the “bricks”. The beneficial combination of crystallinity and porosity leads to greatly enhanced activity of the films in photocatalytic processes, such as the photooxidation of NO. Acting as the active layers in dye-sensitized solar cells, films of only 2.7 μm in thickness exhibit a conversion efficiency of 6.0%.LP
Some developments of solid-state sodium batteries in Forschungszentrum Jülich
No full textSome developments of solid-state sodium batteries in Forschungszentrum JülichQianli Ma1, Tu Lan1, Chih-Long Tsai1, Frank Tietz1, Dina Fattakhova-Rohlfing1,2, Olivier Guillon1,3 1. Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), 52425 Jülich, Germany2. Department of Engineering and Center for Nanointegration Duisburg‐Essen (CENIDE), Universität Duisburg‐Essen, 47057 Duisburg, Germany3. Jülich Aachen Research Alliance, JARA-Energy, 52425 Jülich, Germanye-mail address: [email protected] to their lithium counterpart, solid-state sodium battery (SSNB) is regarded to have similar properties but is a much less mature technology because it is much less addressed. Besides their well-known natural endowment like high element abundance, low price etc., in the present study, some technological advantages of SSNBs are discussed in comparison with solid-state lithium batteries (SSLBs). Very recently, Na3.4Zr2Si2.4P0.6O12 (NZSP) ceramics were reported to have total conductivity of 5 × 10-3 S cm-1 at 25 °C, higher than previously reported polycrystalline Na-ion conductors.[1] Inhibition of dendrite growth in SSLBs and SSNBs has long been a challenge to the field. In the present study, with simply sticking sodium metal to NZSP ceramic pellets and without external pressure applied during operation, the critical current density of Na/NZSP/Na symmetric SSNBs reaches 9 mA cm-2 at 25°C. The cells can be stably operated at areal capacity of 5 mAh cm-2 (per half cycle, with 1.0 mA cm-2) at 25°C for 300 h in a galvanostatic cycling measurement without any dendrite formation. This critical current density is much higher than those of existing SSLBs operated at similar conditions. The influence of metal self-diffusion on the dendritic plating is the main explanation of the high dendrite tolerance of SSNBs. In this report, the inter-ceramic contact problems in the cathode are also solved by combining the infiltration of a porous electrolyte scaffold by precursor solution with in situ synthesis of electrode active material.[2,3] The resulting full cells using Na3V2P3O12, NZSP and Na as the positive electrode, electrolyte and negative electrode materials, respectively, can be stably operated with a capacity of 0.55 mAh cm-2 at high rate of 0.5 mA cm-2. This is the first successful example showing that contact problems between rigid electrolyte and electrode materials can be solved without using any soft phase (liquid, polymers, ionic liquids etc.) as an accommodation or wetting medium. Since SSNBs have these advantages while SSLBs have not, the future roadmap of the development of solid-state batteries may shift from SSLBs towards SSNBs despite the higher molar weight of the sodium compounds in comparison to the Li analogues.[1] Q. Ma, C.-L. Tsai, X.-K. Wei, M. Heggen, F. Tietz, J. T. S. Irvine, J. Mater. Chem. A, 2019, 7, 7766–7776.[2] T. Lan, C.-L. Tsai, F. Tietz, X.-K. Wei, M.Heggen, R. E. Dunin-Borkowski, R.Wang, Y. Xiao, Q. Ma, O. Guillon, Nano Energy, 2019, 65, 104040. [3] C.-L. Tsai, T. Lan, C. Dellen, Y. Ling, Q. Ma, D. Fattakhova-Rohlfing, O. Guillon, F. Tietz, J. Power Sources 2020, 476, 228666
About Dina Rubina - with love...
No full textThe author of the article offers a review of a book Manovskii I. "Dina Rubina yesterday and today"
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