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Post mortem/operando XPEEM: for studying the surface of single particle in Li-ion battery electrodes
X-ray photoemission electron microscopy (XPEEM) with its excellent spatial resolution is a well-suited technique to elucidate the complex electrode-electrolyte interface reactions in Li-ion batteries. It provides element-specific contrast images and enables the acquisition of local X-ray absorption spectra on single particles. Here we demonstrate the strength of post mortem measurements and we show the first electrochemical cell dedicated for operando experiments in all-solid-state batteries.
Excellent cycling stability of graphite in all-solid-state battery using sulfide solid electrolyte
All-solid-state lithium ion batteries represent a promising battery technology for boosting the volumetric energy density and promising a superior safety. In this study excellent cycling stability of graphite anode material have been demonstrated in combination with sulfide-based solid electrolyte. Furthermore we evaluated the stability of the graphite-electrolyte interface by analyzing the normalized cumulative irreversible charge during cycling experiments.
Open Positions
Investigation of the electrochemical performance and the surface layer formation of cycled thin films of amorphous Si in carbonate and ionic liquid based electrolytes
LEC Publications
Some selected Review Articles, Book Chapters, or Books from the Laboratory For a complete list of publications see PUBLICATIONS ANNUAL.
Publications 2018
Electrochemistry Laboratory (LEC)
High performance doped Li-rich Li1+xMn2-xO4 cathodes nanoparticles synthesized by facile, fast and efficient microwave-assisted hydrothermal route
Li-rich nanoparticles of Li1+xMn2-xO4 doped with Al, Co or Ni are successfully synthesized using a facile, fast and efficient microwave-assisted hydrothermal route. In this study, we demonstrate that nanocrystallinity and cationic doping play an important role in improving the electrochemical performance with respect to LiMn2O4 microparticles. They significantly reduce the charge-transfer resistance, lower the 1st cycle irreversible capacity to 6%, and achieve a capacity retention between 85 and 90% after 380 cycles, with excellent columbic efficiency close to 99%.
LEC Events/Seminars
Die Seminare finden im Raum ODRA/111 jeweils am Mittwoch um 11:00 Uhr statt. Externe Gäste (ausserhalb des PSI) sind willkommen, werden aber gebeten, sich im Labor-Sekretariat bei Frau Cordelia Gloor unter Tel.: +41 56 310 2919 oder per e-mail anzumelden. Lectures take place in room ODRA/111 on every Wednesday at 11:00 am. External guests (from outside PSI) are welcome, but are requested to register with our secretary Cordelia Gloor at phone: +41 56 310 2919 or via e-mail.
Reactivity and potential profile across the electrified LiCoO2-Li3PS4 interface probed by operando X-ray photoelectron spectroscopy
All-solid-state lithium batteries are a promising alternative for next generation of safe energy storage devices, provided that parasitic side reactions and the resulting hindrances in ionic transport at the electrolyte-electrode interface can be overcome. Motivated by the need for a fundamental understanding of such interface, we present here real-time measurements of the (electro-)chemical reactivity and local surface potential at the electrified interface Li3PS4 and LiCoO2 using operando X-ray photoelectron spectroscopy.
Li-ion solvation in TFSI and FSI - based ionic liquid electrolytes probed by X-ray photoelectron spectroscopy
We demonstrate the capability of conventional laboratory XPS to determine the anions solvation shell of Li+ cation within 1M of LiTFSI and 1M of LiFSI salts dissolved in (EMIM+-FSI-) and (EMIM+-TFSI-) ionic liquids. The binding energy difference between the N1s components originating from the EMIM+ cation and from TFSI- or FSI- anions, solvating the Li+, confirms that both TFSI- and FSI- contribute simultaneously to the Li+ solvation. Additionally, the degradation of the TFSI and FSI -based electrolytes under X-ray exposure is proved.
Integration of Li4Ti5O12 crystalline films on silicon towards high-rate performance lithionic devices
The growth of crystalline Li-based oxide thin films on silicon substrates is essential for the integration of next-generation solid-state lithionic and electronic devices. In this work, we employ a 2 nm γ-Al2O3 buffer layer on Si substrates in order to grow high quality crystalline thin films Li4Ti5O12 (LTO). Long-term galvanostatic cycling of 50 nm LTO demonstrates exceptional electrochemical performance, specific capacity of 175 mAh g-1 and 56 mAh g-1 at 100C and 5000C respectively, with a capacity retention of 91% after 5000 cycles.
Understanding the (de-)lithiation mechanism of nano-sized LiMn2O4 allows achieving long-term cycling stability
We report an in-depth investigation of the local atomic geometry, electronic and crystallographic structure evolution of nano-sized LiMn2O4 using operando XAS and XRD to shed light on (de-)lithiation mechanism when cycled in wide voltage range of 2.0 to 4.3 V vs Li+/Li. Leveraging on these findings, a novel electrochemical cycling protocol, with periodic deep discharge, yields superior electrochemical performance cycled in the range of 3.3 to 4.3 V exhibiting an excellent structure cyclability and an unprecedented increase in the specific capacity upon long cycling.