SoLiK Li-hochleitende Keramiken für all-solid-state Batterien

Projektverlauf

The workflow in the SoLiK project was:

1. Synthesis of Al, Ga, Ta, and Nb doped LLZO garnet electrolytes via mixing oxides and sol-gel methods. The highest Li ionic conductivity was measured in the sample of LLZO-Ga0.2 pfu (per formular unit) to be ~1.2 mS/cm through the electrochemical impedance spectroscopy method.

2. Successful sintering of highly densified LLZO samples and LLZO samples with large grains -up to 1 mm- by optimizing sintering temperature, time, atmosphere, etc.

3. Microelectrode technology was successfullly applied to measure the local Li ionic conductivity in LLZO samples, and the distribuiton of local Li ionic conductivity in LLZO samples agreed well with the chemical distribution of Lithium element in the same sample determined by LA- ICP MS (Laser Ablation Induced Coupled Plasma Mass Spectroscope).

4. Densified and uniform LLZO-Ga0.2 thin films with a thickness of ~200nm were deposited on substrates of Si, SiO₂, glasses, Al, and Au by magnetron sputtering method, and their crystalline structures, morphologies, and electrochemical properties were characterized by XRD, SEM, and EIS respectively.

5. LLZO thick films from LLZO powders were prepared directly on commerical anode and cathode films to form the composite LLZO/anode and LLZO/cathode films, and all-solid-state lithium-ion batteries were prepared based on the composite LLZO/electrode films. Characterization of EIS and charging-discharging curves of the all-solid-state lithium-ion batteries prototypes gave a comprehensive picture of the materials‘ performance.

Meilensteine

1. Synthesis of garnet structured LLZO ceramics doped with Al, Ga, Ta and Nb element with high density and varied grain sizes
2. Phase and chemical analysis of bulk samples and single crystals
3. Electrochemical analysis of the Li ionic conductivity of bulk samples with macro electrode and micro electrode
4. Correlation of quantitative chemical analysis with the ionic conductivity of doped garnet LLZO samples
5. Preparation of LLZO-Ga thin films via magnetron sputtering technology
6. Phase analysis and ionic conductivity measurement of LLZO thin films
7. Preparation of all-solid-state batteries based on thick film of LLZO-Ga and electrochemical analysis

Ergebnisse

Reasonable electrochemical performance was achieved for the thick film batteries when a very small amount of liquid electrolyte was added. We hope that in future projects the solid electrolyte can be made thin enough so that this addition is no longer necessary.

Since this was a basic science project, success is measured in scientific publications rather that in prototype performance.

An international workshop on solid lithium ion conductors was successfully held at TechGate, Vienna, on May 20, 2015, where several European scientists as well as the SoLiK consortium presented their researches on solid lithium electrolytes from theory to practical application, and shared their anticipation on the furture development of solid electrolytes for electrical energy storage.

As to the dissemination of the project results, seven articles have been or will be published in internationally renowned journals such as „Chemistry of Materials“, „Solid State Ionics“, the „Journal of Electroceramics“, etc. The project also yielded two successful master’s theses and two doctoral dissertations.

Several posters/presentations were or will be shown at international conferences on lithium ion batteries (ABAA9, Batteries Event 2017, and TRA2018, etc.).