O1 - Forschungszentrum Jülich GmbH - IEK1
Prof. O. Guillon
Prof. D. Fattakhova-Rohlfing
Dr. M. Finsterbusch
Dr. S. Uhlenbruck
Dr. F. Tietz

This subproject focuses on the oxide- and phosphate-based solid electrolytes. In terms of safety, processability and environmental compatibility, they represent two extremely promising material classes: oxides such as garnet-like LLZ and phosphate-based NaSICON structures (LATP). For both systems, however, bottlenecks in the availability of high-quality materials for the German research landscape have been identified. In addition, the materials must be optimized regarding their further processing into cell components and entire solid-state batteries. Therefore, this subproject aims to address these pressing research and development problems in a focused way.

O2 - Fraunhofer IKTS
Dr. M. Wolter
Dr. M. Kusnezoff

The sub-project focuses on the preparation and processing of the phosphate solid electrolyte LATP (Li_1.3Al_0.3Ti_1.7(PO₄)₃). In order to create the material basis for manufacturing of all-solid-state batteries, the synthesis is optimized and scaled up to pilot plant scale in the kilogram range. The second research focus aims at reducing the sintering temperature of LATP. On the one hand, sintering additives are investigated to enable component production at moderate temperatures. On the other hand, the reduced sintering temperature should enable the production of composite cathodes including LATP as ion conducting phase. For this purpose, the reaction behaviour of different cathode active materials towards LATP at elevated temperature is investigated and furthermore, a reduction of the reactivity is aimed at by coatings on the active material particles. The work is accompanied by the continuous development of electrochemical measurement methods to characterize the functions of the composite cathode (storage, Li-conduction and electron conduction) and to separate the different conduction mechanisms.

O3 - Karlsruher Institut für Technologie, KIT - IAM
Prof. M.J. Hoffmann

LATP and LLTO have a large application potential as lithium ion conductive solid electrolytes, since they already have comparable grain conductivities to liquid electrolytes. The targeted substitution of Ti, Al and P or La and Ti is intended to increase both the conductivity of polycrystalline materials and their resistance to metallic lithium. Thereby, dense components at low temperatures shall be produced. Sintering must be carried out without pressure in order to avoid restrictions in the design of an electrochemical cell. In addition, first orienting investigations on the compatibility of the novel solid electrolytes with potential active materials are carried out.

O4 - Universität Duisburg-Essen, Institut für Verbrennung und Gasdynamik (IVG)
Prof. C. Schulz
PD Dr. H. Wiggers

The aim of this subproject is the production of nanoscale starting materials for the manufacture of ceramic lithium-lanthanum-zirconate (LLZO) and lithium-aluminum-titanium-phosphate (LATP) solid electrolytes. The required sintering temperature for densification of ceramics can be significantly reduced by decreasing the particle size to the nanoscale, which offers advantages for the process technology as well as reduces the loss of lithium during sintering. Furthermore, in contrast to microscale materials, nanoscale starting materials allow the production of very thin layers, resulting in significant advantages with respect to total ion conductivity due to short transport distances.

P1 - Helmholtz-Institut Ulm, HIU
Prof. S. Passerini
Dr. D. Bresser

The aim of the subproject is to create a material basis for the critical evaluation of polymer-based electrolyte concepts for solid-state lithium batteries. The work at HIU/KIT is concerned with the identification, synthesis and processing of polymer and gel polymer electrolyte systems - the latter containing low to non-volatile liquid phases, such as ionic liquids - as well as their basic physicochemical and electrochemical characterization, the analysis and preliminary work for upscaling the representation of selected systems and their application in lithium polymer cells.

P2 - Forschungszentrum Jülich GmbH, Institut für Energie und Klimaforschung - Helmholtz-Institut Münster (HI MS): Ionics in Energy Storage (IEK-12)
Prof. M. Winter
Prof. H.-D. Wiemhöfer
PD Dr. G. Brunklaus

The aim is to develop the material basis of solid-state batteries using organic solid and hybrid polymer electrolytes. The focus is on the development, optimization and production of promising solid and hybrid polymer electrolytes. In addition, a collection of reliable reference data will be established, including data on chemical and electrochemical stability of individual classes of materials against lithium metal and high performance cathode materials, which will be used to establish criteria for reliable evaluation of the materials and possibilities for providing cost-effective methods for upscaling the most promising solid and hybrid polymer electrolytes.

P3 - Karlsruher Institut für Technologie (KIT), Institut für Technische Chemie und Polymerchemie (ITCP)
Prof. P. Théato

The aim of the subproject is to create a basis for the critical evaluation of polymer-based electrolyte concepts for the realization of solid-state lithium batteries. The work at the KIT focuses on the identification and synthesis of polymer electrolyte systems as well as their basic physicochemical and electrochemical characterization and, finally, their application in lithium polymer cells. This includes relevant preliminary work for the realization of a stable lithium metal anode, which is planned for the second project phase. Furthermore, the obtained data and results will be made available to the method platform "theory and data" for the creation of a comprehensive database of reference data for quality assurance.

T1 - Max-Planck-Institut für Festkörperforschung, Stuttgart, Nanochemie
Prof. B. Lotsch

The central aim is to test the stability of known and new sulfide electrolytes against cathode active materials and lithium, to evaluate the resulting transport properties in test cells and to clarify reaction paths in order to propose suitable protection concepts if necessary. In addition, the conditions for the long-term stable and reversible lithium metal anode in sulfidic solid-state cells are explored. The structure-property relationships of sulfide solid electrolytes are analyzed and the influence of the synthesis process on phase formation and their conductivities are studied in order to identify optimal synthesis conditions.

T2 - Fraunhofer CES, Abteilung EVA
Prof. A. Kwade

Sulfur-based solid electrolytes show the highest ionic conductivities and at the same time the lowest material availability or highest synthesis times. Scalable process technologies for the production of these electrolytes are not yet known. In addition to production, processing in a composite cathode also poses challenges, since the solid/solid interfaces (e.g. active material/solid electrolyte) are often unstable or inhomogeneous. Therefore, the goals of this subproject are the development of scalable and temperature controlled synthesis procedures and the development of a scalable infiltration process of sulfur-based solid electrolytes into a free-standing cathode.

T3 - MPI für Festkörperforschung, Stuttgart
Prof. B. Lotsch

Although thiophosphates currently have the highest conductivity among solid electrolytes, their use in solid-state batteries is still limited due to microstructure effects and SEI formation and the resulting contact resistances. The low (electro-)chemical stability of sulfide solid electrolytes in relation to the electrodes also calls into question the cycle stability of these systems. The goals are to improve the lithium-ion conductivity, to develop new types of sulfide ion conductors and to develop solid electrolytes that are either kinetically inert towards the electrodes or can be stabilized by the formation of suitable interphases.

T4 - TU Braunschweig, iPAT
Prof. A. Kwade
Dr.-Ing. S. Zellmer

The iPAT subproject develops, evaluates and assesses dry and wet process routes regarding their scalability for the industrial production of lithium thiophosphates. Special emphasis is placed on the resulting product properties as well as on the characterization of material properties to determine data for a superordinate material platform. Furthermore, systematic investigations for the production of electrodes are carried out and the quality of the resulting cathodes is determined under consideration of process and product properties in order to enable a scale-up of cell construction in the 2nd project phase.