Converting the CHF Greenhouse Gas into Nanometer-Thick LiF Coating for High-Voltage Cathode Li-ion Batteries Materials.

Solving the surface (electro-)chemical instability and the fading behavior of high voltage cathode materials cycled above 4.3 V vs Li/Li remains a major challenge for the next generation of high energy density Li-ion batteries. Here, we present a facile, environmentally friendly, cost effective and scalable method to address this problem by uniformly fluorinating the surface of cathode materials with a mild fluorinating agent (CHF) using a gas flow-type reactor.

Synergy of Artificial SEI and Electrolyte Additive for Improved Performance of Silicon Electrodes in Li-Ion Batteries.

Maintaining the electrochemically and mechanically stable solid electrolyte interphase (SEI) is of highest importance for the performance of high-capacity anode materials such as silicon (Si). Applying flexible Li-ion permeable coatings to the electrode surface using molecular layer deposition (MLD) offers a strategy to improve the properties of the SEI and greatly contributes to an increase in the cycle life and capacity retention of Si electrodes. In this study, the long-term cycling of Si electrodes with an MLD alucone coating is investigated in the context of more stable SEI formation.

A Dye-Sensitized Sensor for Oxygen Detection under Visible Light.

Sensors that can accurately assess oxygen (O) concentrations in real time are crucial for a wide range of applications spanning personal health monitoring, environmental protection, and industrial process development. Here a high-performance chemiresistive sensor that allows for the rapid detection of O at room temperature under visible light illumination is described. Inspired by the operating principles of dye-sensitized solar cells, the chemiresistor is based on a single-walled carbon nanotube-titania hybrid (SWCNT-TiO) bearing a molecular Re-based photosensitizer [(bpy)(CO)ReBr] (bpy = 4,4'-[P(O)(OH)]-2,2'-bipyridine).

Triphenylphosphine Oxide: A Versatile Covalent Functionality for Carbon Nanotubes.

Broadening the scope of functionalities that can be covalently bound to single-walled carbon nanotubes (SWCNTs) is crucial for enhancing the versatility of this promising nanomaterial class in applied settings. Here we report the covalent linkage of triphenylphosphine oxide [PhP(O)] to SWCNTs, a hitherto overlooked surface functionality. We detail the synthesis and structural characterization of a new family of phosphine oxide-functionalized diaryliodonium salts that can facilitate direct PhP(O) transfer and afford novel SWCNTs with tunable PhP(O) content (SWCNT-P).

Building Solid-State Batteries: Insights from Swiss Research Labs.

This review article delves into the growing field of solid-state batteries as a compelling alternative to conventional lithium-ion batteries. The article surveys ongoing research efforts at renowned Swiss institutions such as ETH Zurich, Empa, Paul Scherrer Institute, and Berner Fachhochschule covering various aspects, from a fundamental understanding of battery interfaces to practical issues of solid-state battery fabrication, their design, and production. The article then outlines the prospects of solid-state batteries, emphasizing the imperative practical challenges that remain to be overcome and highlighting Swiss research groups' efforts and research directions in this field.

Interfacial Stabilization by Prelithiated Trithiocyanuric Acid as an Organic Additive in Sulfide-Based All-Solid-State Lithium Metal Batteries.

Sulfide-based all-solid-state battery (ASSB) with a lithium metal anode (LMA) is a promising candidate to surpass conventional Li-ion batteries owing to their inherent safety against fire hazards and potential to achieve a higher energy density. However, the narrow electrochemical stability window and chemical reactivity of the sulfide solid electrolyte towards the LMA results in interfacial degradation and poor electrochemical performance. In this direction, we introduce an organic additive approach, that is the mixing of prelithiated trithiocyanuric acid, LiTCA, with LiPSCl, to establish a stable interface while preserving high ionic conductivity.

Surface oxidation/spin state determines oxygen evolution reaction activity of cobalt-based catalysts in acidic environment.

Co-based catalysts are promising candidates to replace Ir/Ru-based oxides for oxygen evolution reaction (OER) catalysis in an acidic environment. However, both the reaction mechanism and the active species under acidic conditions remain unclear. In this study, by combining surface-sensitive soft X-ray absorption spectroscopy characterization with electrochemical analysis, we discover that the acidic OER activity of Co-based catalysts are determined by their surface oxidation/spin state.

Molecular regulation of electrolytes for enhancing anode interfacial stability in lithium-sulfur batteries.

We addressed the poor interfacial stability of the Li metal anode in Li-S batteries through molecular regulation of electrolytes using arylthiol additives with various numbers of anchoring sites. The dual functional tetrathiol additive markedly enhanced the Li anode interfacial stability, controlled the sulfur redox kinetics and suppressed side reactions towards polysulfides, thus leading to an improved capacity retention of 70% after 500 cycles at 1 C.

Integration of LiTiO Crystalline Films on Silicon Toward 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 including on-chip microbatteries, memristors, and sensors. However, growing crystalline oxides directly on silicon typically requires high temperatures and oxygen partial pressures, which leads to the formation of undesired chemical species at the interface compromising the crystal quality of the films. In this work, we employ a 2 nm gamma-alumina (γ-AlO) buffer layer on Si substrates in order to grow crystalline thin films of LiTiO (LTO), a well-known active material for lithium-ion batteries.

Fluorinated ether electrolyte with controlled solvation structure for high voltage lithium metal batteries.

The development of new solvents is imperative in lithium metal batteries due to the incompatibility of conventional carbonate and narrow electrochemical windows of ether-based electrolytes. Whereas the fluorinated ethers showed improved electrochemical stabilities, they can hardly solvate lithium ions. Thus, the challenge in electrolyte chemistry is to combine the high voltage stability of fluorinated ethers with high lithium ion solvation ability of ethers in a single molecule.

Integrated Ring-Chain Design of a New Fluorinated Ether Solvent for High-Voltage Lithium-Metal Batteries.

Ether-based electrolytes offer promising features such as high lithium-ion solvation power and stable interface, yet their limited oxidation stability impedes application in high-voltage Li-metal batteries (LMBs). Whereas the fluorination of the ether backbone improves the oxidative stability, the resulting solvents lose their Li -solvation ability. Therefore, the rational molecular design of solvents is essential to combine high redox stability with good ionic conductivity.

Elucidating the Humidity-Induced Degradation of Ni-Rich Layered Cathodes for Li-Ion Batteries.

Ni-rich layered oxides, in a general term of Li(NiCoMn)O ( > 0.5), are widely recognized as promising candidates for improving the specific energy and lowering the cost for next-generation Li-ion batteries. However, the high surface reactivity of these materials results in side reactions during improper storage and notable gas release when the cell is charged beyond 4.

Reactivity and Potential Profile across the Electrochemical LiCoO-LiPS Interface Probed by X-ray Photoelectron Spectroscopy.

All-solid-state lithium batteries are a promising alternative for next-generation 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 an interface, we present here real-time measurements of the (electro-)chemical reactivity and local surface potential at the electrified interface (LiS)-PS (LPS) and LiCoO (LCO) using X-ray photoelectron spectroscopy (XPS) supplemented by X-ray photoemission electron microscopy (XPEEM). We identify three main degradation mechanisms: (i) reactivity at open circuit potential leading to the formation of reduced Co in the +2 oxidation state at the LCO surface, detected in the Co L-edge, which is further increased upon cycling, (ii) onset of electrochemical oxidation of the LPS at 2.

Cross-Talk-Suppressing Electrolyte Additive Enabling High Voltage Performance of Ni-Rich Layered Oxides in Li-Ion Batteries.

Control of electrode-electrolyte interfacial reactivity at high-voltage is a key to successfully obtain high-energy-density lithium-ion batteries. In this study, 2-aminoethyldiphenyl borate (AEDB) is investigated as a multifunctional electrolyte additive in stabilizing surface and bulk of both Ni-rich LiNi Co Mn O (NCM851005) and graphite electrodes in a cell operated with elevated upper cutoff voltage of 4.4 V vs.

Unveiling the Complex Redox Reactions of SnO in Li-Ion Batteries Using X-ray Photoelectron Spectroscopy and X-ray Absorption Spectroscopy.

We experimentally determine the redox reactions during (de-)lithiation of the SnO working electrode cycled in (LiS)-PS solid electrolyte by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. Specifically, we have accurately determined the composition changes in the SnO working electrode upon cycling and identified the onset voltage formation of the various phases. Starting from the open-circuit potential, we find that, on lithiation, the Sn M-edge absorption spectra reveal unequivocally the formation of SnO ( ≤ 1) and LiSnO already at a potential of 1.

Multi-length-scale x-ray spectroscopies for determination of surface reactivity at high voltages of LiNiCoAlO vs LiTiO.

The surface evolution of LiNiCoAlO (NCA) and LiTiO (LTO) electrodes cycled in a carbonate-based electrolyte was systematically investigated using the high lateral resolution and surface sensitivity of x-ray photoemission electron microscopy combined with x-ray absorption spectroscopy and x-ray photoelectron spectroscopy. On the cathode, we attest that the surface of the pristine particles is composed of adventitious LiCO together with reduced Ni and Co in a +2 oxidation state, which is directly responsible for the overpotential observed during the first de-lithiation. This layer decomposes at 3.

and XPEEM: a Surface-Sensitive Tool for Studying Single Particles in Li-Ion Battery Composite Electrodes.

X-ray photoemission electron microscopy (XPEEM), with its excellent spatial resolution, is a well-suited technique for elucidating the complex electrode-electrolyte interface reactions in Li-ion batteries. It provides element-specific contrast images that allows the study of the surface morphology and the identification of the various components of the composite electrode. It also enables the acquisition of local X-ray absorption spectra (XAS) on single particles of the electrode, such as the C and O K-edges to track the stability of carbonate-based electrolytes, F K-edge to study the electrolyte salt and binder stability, and the transition metal L-edges to gain insights into the oxidation/reduction processes of positive and negative active materials.

On the Oxidation State of Cu O upon Electrochemical CO Reduction: An XPS Study.

The encouraging selectivity of copper oxides for the electroreduction of CO into ethylene and alcohols has led to a vivid debate on the possible relation between their operando (sub-)surface oxidation state (i. e. fully reduced or partially oxidized) and this distinct reactivity.

Revealing the Dual Surface Reactions on a HE-NCM Li-Ion Battery Cathode and Their Impact on the Surface Chemistry of the Counter Electrode.

The understanding of surface reactions at the electrode-electrolyte interfaces has been a longstanding challenge in Li-ion batteries. X-ray photoemission electron microscopy is used to throw light on the disputed aspects of the surface reactivity of high-energy Li-rich Li(Ni Co Mn)O (HE-NCM) cycled in an aprotic electrolyte against LiTiO (LTO). Despite the highly oxidative potential of 5.

Monitoring the chemical and electronic properties of electrolyte-electrode interfaces in all-solid-state batteries using operando X-ray photoelectron spectroscopy.

Understanding the degradation of the solid electrolyte-electrodes interface during cycling is currently one of the most challenging obstacles in the development of all-solid-state batteries. Here, we introduce operando X-ray photoelectron spectroscopy (XPS) as a combined approach for real-time monitoring of the (i) (electro-) chemical interfacial reactions between different components of the composites electrode and (ii) surface electronic properties. The dedicated electrochemical cell, capable of maintaining high mechanical pressure, offers reliable electrochemistry and versatility in terms of materials application.

SnO Model Electrode Cycled in Li-Ion Battery Reveals the Formation of LiSnO and LiSnO Phases through Conversion Reactions.

SnO is an attractive negative electrode for Li-ion battery owing to its high specific charge compared to commercial graphite. However, the various intermediate conversion and alloy reactions taking place during lithiation/delithiation, as well as the electrolyte stability, have not been fully elucidated, and many ambiguities remain. An amorphous SnO thin film was investigated for use as a model electrode by a combination of postmortem X-ray photoelectron spectroscopy supported by density functional theory calculations and scanning electron microscopy to shed light on these different processes.

Elucidating the Surface Reactions of an Amorphous Si Thin Film as a Model Electrode for Li-Ion Batteries.

We investigated during the first lithiation/delithiation process the electrochemical reaction mechanisms at the surface of 30 nm n-doped amorphous silicon (a-Si) thin film used as a negative model electrode for Li-ion batteries. Usage of thin film allowed us to accurately discern the different reaction mechanisms occurring at the surface by avoiding interference from carbon and binder components. The potential dependency of the evolution of the solid electrolyte interphase (SEI) and the reactions on the a-Si and on the copper current collector were elucidated by coupling galvanostatic cycling with postmortem X-ray photoemission spectroscopy and scanning electron microscopy analyses.

Size-Resolved Identification, Characterization, and Quantification of Primary Biological Organic Aerosol at a European Rural Site.

Primary biological organic aerosols (PBOA) represent a major component of the coarse organic matter (OMCOARSE, aerodynamic diameter > 2.5 μm). Although this fraction affects human health and the climate, its quantification and chemical characterization currently remain elusive.

One-Pot Polyol Synthesis of Pt/CeO2 and Au/CeO2 Nanopowders as Catalysts for CO Oxidation.

The facile one-pot synthesis of CeO2-based catalysts has been developed to prepare a relatively large amount of nanopowders with relevant catalytic activity towards CO oxidation. The method consists of a two-steps process carried out in ethylene glycol: in the first step, 5 nm well-crystallized pure CeO2 is prepared. In a subsequent second step, a salt of a noble metal is added to the CeO2 suspension and the deposition of the noble metal on the nanocrystalline CeO2 is induced by heating.