Suchen

Degradation of the solid-electrolyte interface occurring during cycling is currently one of the most challenging issues for the development of all-solid-state batteries. Here we designed a unique electrochemical custom made cell for operando X-ray photoelectron spectroscopy (XPS) capable of maintaining high mechanical pressure with reliable electrochemistry and able to monitor in real-time the surface (electro-)chemical reactivity at the interfaces between the different composite.

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.

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.

Li-rich nanoparticles of Li_1+xMn_2-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 1^st cycle irreversible capacity to 6%, and achieve a capacity retention between 85 and 90% after 380 cycles, with excellent columbic efficiency close to 99%.

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.

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.   

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.

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.

PSI researchers have identified a novel electrolyte additive, allowing extended voltage range of Ni-rich oxide full-cells, while keeping excellent performance. The instability of cathode–electrolyte interface causes the structural degradation of cathode active material and the electrolyte consumption, resulting in a rapid capacity fading and shortening battery life-time. The PSI-identified additive help to alleviate these problems and extend battery life-time.

Control of interfacial reactivity at high-voltage is a key to high-energy-density Li-ion batteries. 2-aminoethyldiphenyl borate was investigated as an electrolyte additive to stabilize surface and bulk of both NCM851005 and graphite in the cell with upper cut-off voltage of 4.4 V vs Li+/Li. AEDB almost completely eliminated the “cross-talk” in the cell, by significantly reducing metal leaching from the cathode, preventing their deposition at the anode, and further electrolyte decomposition.

Fluoroethylene-carbonate is often referred to as a film-forming electrolyte additive for Li-ion batteries, resulting in high quality Solid–Electrolyte-Interphase on negative electrode, however, the underlying mechanism, even if thought to be known, has been only clarified due to our targeted experimental design, combining systematic electrochemical, chemical and microscopy characterization techniques. We have shown that first the formation of inorganic LiF-rich particles appear and only later the carbonate-rich film is actually formed.

Our findings disclose that P-functionalization successfully enhances the oxygen evolution reaction (OER) activity of different cobalt-based catalysts (namely, La_0.2Sr_0.8CoO_3–δ, La_0.2Sr_0.8Co_0.8Fe_0.2O_3–δ, and CoO_x) at near-neutral pHs and that both phosphate ion assistance in the OER mechanism and catalyst Co oxidation state can play a role in the enhanced OER activity.