SOL4BAT

Fabrication and diagnostics of stable solid-solid interfaces for next-generation Li-ion batteries

The explosive growth of e-mobility has caused a massive demand for Li-ion batteries. More than 20 so-called gigafactories have been announced in Europe to scale up the fabrication of the current generation of Li-ion batteries (LIBs) based on graphite anodes, intercalation-type metal oxide cathodes, and organic liquid electrolytes (Gen 2).

At the same time, many battery and automotive industries have already formed strong alliances to develop solid-state batteries (SSBs) of Gen 4. In addition to the improved safety aspects by replacing the liquid organic electrolyte with a solid Li-conducting electrolyte, the SSB technology offers the advantage of using metallic lithium on the negative electrode. A higher gravimetric energy density of over 450 Wh/kg should be feasible as well as reduction of charging times from the current 30-40 minutes to less than 15 minutes.

Replacing liquid electrolyte in the conventional Li-ion battery (Gen1/2/3, left) with a solid electrolyte (SE) in solid-state batteries (Gen4, right) implies the existence of at least three critical solid-solid interfaces (SSIs).

However, there are several technological and manufacturing challenges on the way to demonstrate a SSB (right) with performance exceeding that for the state-of-the-art Gen 2 batteries (left). Many of these are related to the use of metallic lithium. Another group of challenges is associated with the various solid-state interfaces (SSIs) between ...

Solid electrolyte (SE) and cathode active material particles,
Cathode material and solid electrolyte separator (SES), and
SES and metallic lithium.

Scope of Research Activities
The project aims to investigate whether it is possible to fabricate solid-solid interfaces (SSIs) between solid electrolytes and high-voltage cathode materials, which should remain stable during operation (cycling). The main idea is to employ interlayers at the critical SSIs, which should i) ensure necessary Li-ion transport, ii) release mechanical stresses at SSIs, and iii) suppress undesirable interdiffusion and degradation reactions at the SSIs.

The project will follow two parallel design and manufacturing strategies to address the postulated technological challenges:

"Soft" interlayers: develop a slurry-based manufacturing process of hybrid polymer-inorganic SE composites
"Hard" interlayers: Determine effectiveness of vacuum-based PVD oxide passivation coatings for SE/cathode interface

In addition to the design and the manufacturing of the interlayers, the project team will develop and use new methods to characterize the SSIs and their behavior over time:

X-ray-based methodologies such as XAS and XPEEM to detect the degradation of materials and interfaces
3D imaging methods such as high-res FIB-SEM (10 nm) and synchrotron X-ray (50 nm) tomography to visualize internal interfaces of hybrid composites
Temperature-dependent transient current measurements to quantify ion dynamics (mobility and concentration of mobile Li ions) in solid electrolytes

Key Challenges and Technical Problems to Solve

Fabricatation of solid-solid interfaces with an ultimate close conformal contact
Maintain stable solid interfaces during operation (cycling)

Demonstrators

Sample holder adapted for operando XAS of SSB (in cooperation with tech transfer center ANAXAM).
Software code for extracting mobile Li ions metrics (concentration & mobility) from transient current measurements.

Linked Scientific Publications

2021

Baade, P. and V. Wood (2021). "Ultra-high throughput manufacturing method for composite solid-state electrolytes." iScience 24(2): 102055.
Chen, K.-H., V. Goel, M. J. Namkoong, M. Wied, S. Müller, V. Wood, J. Sakamoto, K. Thornton and N. P. Dasgupta (2021). "Enabling 6C Fast Charging of Li-Ion Batteries with Graphite/Hard Carbon Hybrid Anodes." Advanced Energy Materials 11(5): 2003336.
Priebe, A., J. Sastre, M. H. Futscher, J. Jurczyk, M. V. Puydinger dos Santos, Y. E. Romanyuk and J. Michler (2021). "Detection of Au+ Ions During Fluorine Gas-Assisted Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) for the Complete Elemental Characterization of Microbatteries." ACS Applied Materials & Interfaces 13(34): 41262-41274.
Sastre, J., M. H. Futscher, L. Pompizi, A. Aribia, A. Priebe, J. Overbeck, M. Stiefel, A. N. Tiwari and Y. E. Romanyuk (2021). "Blocking lithium dendrite growth in solid-state batteries with an ultrathin amorphous Li-La-Zr-O solid electrolyte." Communications Materials 2(1): 76.

2020

Sastre, J., A. Priebe, M. Döbeli, J. Michler, A. N. Tiwari and Y. E. Romanyuk (2020). "Lithium Garnet Li7La3Zr2O12 Electrolyte for All-Solid-State Batteries: Closing the Gap between Bulk and Thin Film Li-Ion Conductivities." Advanced Materials Interfaces 7(17): 2000425.

2019

Sastre, J., T.-Y. Lin, A. N. Filippin, A. Priebe, E. Avancini, J. Michler, A. N. Tiwari, Y. E. Romanyuk and S. Buecheler (2019). "Aluminum-Assisted Densification of Cosputtered Lithium Garnet Electrolyte Films for Solid-State Batteries." ACS Applied Energy Materials 2(12): 8511-8524.

Leading Principal Investigator

Dr. Yaroslav Romanyuk
Laboratory for Thin Films and Photovoltaic (LTFPV), Empa

Project Consortium

Prof. Dr. Vanessa Wood
Laboratory for Nanoelectronics, ETH Zürich
Dr. Mario El Kazzi
Electrochemistry Laboratory (LEC), PSI
Dr. Carlos A. F. Vaz
Surface/Interface: Microscopy (SIM) Beamline, PSI