Search

Li(Ni0.80Co0.15Al0.05)O2 is a lithium-ion battery cathode, commercially available for more than twenty years, which is associated with high energy capacity and high energy density, with moderate power. Atomic layer fluorination (ALF) of Li(Ni0.80Co0.15Al0.05)O2 with XeF2 is performed to improve its cyclability. The ALF method aims at forming an efficient protecting fluorinated layer at the surface of the material, with a low fluorine content. Surface fluorinated Li(Ni0.80Co0.15Al0.05)O2 is characterized by X-ray diffraction, electron microscopy, 19F nuclear magnetic resonance, X-ray photoelectron spectroscopy, and galvanostatic measurements, and a fluorine content as low as 1.4 wt% is found. The presence of fluorine atoms improves the electrochemical performances of Li(Ni0.80Co0.15Al0.05)O2: cyclability, polarization and rate capability are improved. Operando infrared spectroscopy and post-mortem gas chromatography provide some insights into the origins of these improvements. [ABSTRACT FROM AUTHOR]

Lithium solid-state batteries (SSBs) are a promising technology for electrochemical energy storage systems. So far, the performance of SSBs are mainly governed by the electro-chemo-mechanical properties of the diverse solid/solid interfaces and their evolution upon cycling. However, as these interfaces are buried in the battery stack, their comprehensive understanding remains a challenge. Here, we thus provide some advances in methodological developments for ex situ, in situ and operando cycling/analysis of these buried interfaces. It is showed that noble gaz ion milling at liquid nitrogen temperature is a suitable and reproducible method to prepare cross-section without any chemical/physical change even for polymer-based SSBs. In addition, innovative operando cycling using Auger analysis was proposed for the first time on a model Li/Li6PS5Cl stack. The interest of this approach is to be able to proceed without a dedicated electrochemical cell and to use the fully adjustable electron beam of the auger to create a surface potential difference followed by lithium migration then SEI (Solid Electrolyte Interface) formation and Li plating. Overall, this work should greatly benefits to all researchers working on buried interfaces study in lithium solid-state batteries.

The need of more powerful systems with higher energy density raises a lot of interest in lithium metal batteries (LMBs). As LMBs suffer from safety concerns due to the dendrite growth, several strategies have been studied to limit this growth. Using a highly concentrated electrolyte allows a homogeneous lithium plating that delays the formation of dendrites. Herein, different techniques are used in order to better understand the beneficial role of the salt concentration in the lithium plating/stripping. Operando Fourier transform infrared spectroscopy highlights the better reversibility of the Li+ solvation in the 5 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1,2‐dioxolane/1,3‐dimethoxyethane electrolyte in comparison with the 1 M electrolyte. This obviously leads to different electrolyte decompositions during the lithium plating/stripping and changes the nature of the electrode solid electrolyte interphase (SEI) depending on the salt concentration. Gas chromatography coupled with mass spectrometry as well as X‐ray photoelectron spectroscopy confirms that with the 5 M LiTFSI electrolyte the salt is preferentially reduced during the plating/stripping, leading to a more inorganic SEI on the lithium metal electrode. [ABSTRACT FROM AUTHOR]

II–V semiconductor nanocrystals such as Cd3P2 and Zn3P2 have enormous potential as materials in next-generation optoelectronic devices requiring active optical properties across the visible and infrared range. To date, this potential has been unfulfilled due to their inherent instability with respect to air and moisture. Core-shell system Cd3P2/Zn3P2 is synthesized and studied from structural (morphology, crystallinity, shell diameter), chemical (composition of core, shell, and ligand sphere), and optical perspectives (absorbance, emission-steady state and time resolved, quantum yield, and air stability). The improvements achieved by coating with Zn3P2 are likely due to its identical crystal structure to Cd3P2 (tetragonal), highlighting the key role crystallographic concerns play in creating cutting edge core-shell NCs. [ABSTRACT FROM AUTHOR]