Keynote Speaker
Dr. Ruediger Berger
Interphases in Modern Battery Materials
LiNi 0.5 Mn 1.5 O 4 (LNMO) is a promising cathode material owing to its high operating potential of 4.75 V vs Li⁺/Li. However, the high potential triggers electrolyte oxidation. A mechanically robust cathode–electrolyte interphase (CEI) is essential for maintaining structural integrity of high-voltage lithium-ion batteries. The CEI layer functions as a protective barrier that suppresses parasitic reactions under high-voltage conditions. CEI layers are thin (< 20 nm). Therefore assessing their elastic properties is challenging. We applied the scanning force microscopy method which enablinges quantitative mechanical characterization of thin CEI layers on rough composite electrodes surfaces. The pristine crystalline LNMO surface exhibited an elastic modulus of approximately 126±20 GPa, whereas the binder/carbon (b/c) regions had a modulus of 1.9±0.1 GPa. After 200 charge discharge cycles, the elastic modulus became homogeneous with the moduli on the LNMO and b/c regions reaching
4 GPa. This mechanical convergence is supported by a convergence in chemical composition of the interphase between the LNMO and b/c regions. This work provides understanding of interfacial stability and establishes a robust and reproducible framework for quantifying the elastic modulus of interphase layers within composite electrodes, providing insights for the design of stable high-voltage battery systems.
Reservoir-free batteries are designed without a traditional anode material in the manufacturing process. Instead, a current collector is used. When the battery is charged for the first time, lithium deposits onto this collector effectively forming the anode in place. We investigated interface and interphase of the solid electrolyte and current collector materials with operando Kelvin Probe Force Microscopy (KPFM) [2], [3].
These examples that illustrate Scanning Force Microscopy methods are versatile and beneficial for characterizing and understanding batteries and their components.
References:
[1] X. Shi, F. Weber, H.-J. Butt1, R. Berger, Mechanical Properties of Cathode Electrolyte Interphase Layers in High-Voltage Lithium-Ion Batteries, Journal of Materials Chemistry A 2026, doi:10.1039/d5ta09458e.
[2] F. Weber, Till Fuchs, S. Kobayashi, X. Shi, L. Shen, T. Hitosugi, J. Janek, R. Berger, submitted for publication 2026.
[3] F. Weber, C. Zhu, S. Kobayashi, T. Fuchs, T. Hitosugi, J. Janek, R. Berger, Interpretation of Kelvin Probe Force Measurements in Solid-State Electrochemical Cells. ACS Applied Materials & Interfaces 17 (42), pp. 58825 - 58836 (2025).