The performance degradation of graphite/LiNi1/3Mn1/3Co1/3O2 (NMC) lithium ion cells, charged and discharged up to 300 cycles at different operating conditions temperature upper cutoff potential (4.2V/25°C, 4.2V/60°C, 4.6V/25°C) was investigated. A combination electrochemical methods with X-ray diffraction (XRD) both in situ ex as well neutron induced Prompt-Gamma-Activation-Analysis (PGAA) allowed us elucidate the main failure mechanisms investigated cells. In XRD investigations NMC material...

Aprotic Li-O2 cells have attracted considerable research interest due to its outstandingly high theoretical specific capacity. However, published discharge capacities vary considerably among different researchers despite only minor differences in the tested cell components. Some groups observe low and formation of passivating layers Li2O2 on electronically conducting cathode support, while other report large toroidal crystals as product. In this study we show that these may be water protons,...

In the present work, extent and role of oxygen release during first charge lithium- manganese-rich Li1.17[Ni0.22Co0.12Mn0.66]0.83O2 (also referred to as HE-NCM) was investigated with on-line electrochemical mass spectrometry (OEMS). HE-NCM shows a unique voltage plateau at around 4.5 V in charge, which is often attributed decomposition reaction Li-rich component Li2MnO3. For this so-called "activation", it has been hypothesized that electrochemically inactive Li2MnO3 would convert into MnO2...

The instability of currently used electrolyte solutions and the carbon support during charge–discharge in non-aqueous lithium–oxygen cells can lead to discharge products other than desired Li2O2, such as Li2CO3, which is believed reduce cycle-life. Similarly, an O2 atmosphere contains H2O CO2 impurities would LiOH Li2CO3 products. In this work we therefore investigate rechargeability model cathodes pre-filled with four possible Li–air cell products, namely LiOH, Li2O. Using Online...

Ni-rich layered oxides, like NCM-811, are promising lithium-ion battery cathode materials for applications such as electric vehicles. However, pronounced capacity fading, especially at high voltages, still lead to a limited cycle life, whereby the underlying degradation mechanisms, e.g. whether they detrimental reactions in bulk or surface, controversially discussed. Here, we investigate fading of NCM-811/graphite full-cells over 1000 cycles by combination situ synchrotron X-ray powder...

In this study we report the strong effect of water or organic carbonates on specific capacity during first discharge cathode a Li-O2 cell, using Vulcan-based positive electrodes. An improved cell design allowed us to avoid contaminations from atmospheric air and compare in water-free electrolyte with that contaminated cells, getting an increased up one order magnitude. Understanding mechanism limits enhances electrode is very important improve performance durability cells.

Glyme-based electrolytes were studied for the use in lithium-air batteries because of their greater stability towards oxygen reduction reaction intermediates (e.g., superoxide anion radicals (O2˙(-))) produced upon discharge at cathode compared to previously employed carbonate-based electrolytes. However, contradictory results glyme tests employing KO2 as an O2˙(-) source reported literature. For clarification, we investigated with glymes various chain lengths qualitatively using (1)H NMR...

High-energy Li1.17Ni0.19Co0.10Mn0.54O2 (HE-NCM) is a lithium-rich layered oxide with alternating Li- and transition-metal (TM) layers in which excess lithium ions replace transition metals the host structure. HE-NCM offers capacity roughly 50 mAh g–1 higher compared to that of conventional oxides but suffers from loss voltage fade upon cycling. Differential plots (taken over 100 cycles) show origin fading phenomenon bulk issue rather than surface degradation. Although previous studies...

Replacement of conventional cars with battery electric vehicles (BEVs) offers an opportunity to significantly reduce future carbon dioxide emissions. One possible way facilitate widespread acceptance BEVs is replace the lithium-ion batteries used in existing a lithium-sulfur battery, which operates using cheap and abundant raw material high specific energy density. These significant theoretical advantages over technology have generated lot interest system, but development practical...

In this study we report on the direct proportionality between cathode surface area and first discharge capacity of non-aqueous Li-O2 cells using ether-based electrolytes. Seven different highly structured carbon blacks, characterized by areas porosities, were used to prepare non-catalyzed cathodes. Surface measurements porosity analyzes carried out both raw materials electrodes in order estimate fraction accessible electrolyte. The specific cathodes was then normalized over its a strong...

One of the technological barriers to electrification transport is insufficient storage capacity Li-ion batteries on which current electric cars are based. The lithium-sulfur (Li-S) battery an advanced technology whose successful commercialization can lead significant gains in and promote wide-spread adoption vehicles. Recently, important Li-S intermediates, including polysulfides, S3•-, Li2S, have been shown present unique X-ray absorption near edge structure (XANES) features at sulfur...

The charging process of micrometer-sized, electrically insulating Li2O2 particles in discharged Li-air battery cathodes is still poorly understood. In this work, we focused on the mechanism model Li2O2/carbon pre-filled electrodes electrolytes based several solvents (a glyme, alkyl carbonates, and ionic liquid (Pyr14TFSI) with without redox mediator (LiI) or water as additives. For that are highly reactive lithium metal and/or lead to shuttling currents within cell, a 2-compartment cell...

The decomposition of lithium peroxide during the charging process lithium–air batteries is investigated. A novel preparation method for electrodes in discharged state, i.e., prefilled with Li2O2 using polyethylene oxide as a binder, presented. composition and reactivity Li2O2-prefilled are examined by thermal analysis coupled on-line mass spectrometry. Voltage profiles gas evolution battery cells correlated its impact on other electrode compounds. It found that both electrochemical enhance...

Working in the area of alkaline fuel cell and electrolyzer technology, Acta S.p.A. developed over past two years catalysts without Platinum Group Metals (PGM), named K14 K18, with high activity for oxygen reduction reaction (ORR) medium. The comparison ORR between K14, K18 commercial 10 wt% Pt on Vulcan XC-72R at 0.9 V vs. RHE (Reversible Hydrogen Electrode) has been carried out using Rotating Disk Electrode (RDE) analysis 0.1 M KOH, showing how an close to Pt/C while is significantly...

The use of 1-methyl-1-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr14TFSI) electrolyte in different Li-O2 cell setups is here investigated. In a one-compartment cell, the pyrrolidinium ion reduced on metallic lithium, producing substantial amounts alkenes and amines. To avoid this, simple two-compartment used, with propylene carbonate as anode Li+-ion solid separator. Another explored option substitution lithium lithiated LTO (LLTO). Unfortunately, absence an SEI leads to...

Ionic liquids are attractive candidates as electrolyte solvents for Li-O2 cells, primarily due to their low volatility, high anodic stability, and flammability. Specifically, the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) has attracted considerable attention thanks its electrochemical chemical stability. In this work, we demonstrate via our recently developed UV-Vis screening method that Pyr14TFSI unfortunately reacts with superoxide radical (O•...

The oxygen reduction reaction (ORR) activity of ZrO2 based, carbon-supported nanoparticles is not conclusively reported in literature. This study examines the dependence ORR on used precursors as well heat-treatment atmosphere and temperature. We further determine activation energy mechanism. Various containing Zr and/or N were employed synthesis, was measured by rotating (ring) disk electrode (R(R)DE) voltammetry both acidic alkaline electrolyte measurements a single-cell polymer membrane...

Platinum-group-metal-free (PGM-free) catalysts are currently considered as potential oxygen-reduction-reaction (ORR) to replace costly and supply-limited platinum at the cathode side of proton exchange membrane fuel cells (PEMFCs). Extensive research efforts have led substantial progress with regards ORR activity PGM-free catalysts, but there is uncertainty about dependence mass on catalyst loading. In this study, effect loading investigated by means rotating disk electrode measurements well...

In this contribution, we demonstrate the presence of high-spin Fe3+ in Fe-substituted ZrO2 (FexZr1−xO2−δ), as deduced from X-ray photoelectron spectroscopy (XPS), near-edge absorption fine structure (NEXAFS), and 57Fe Mössbauer measurements. The activity carbon-supported FexZr1−xO2−δ catalyst toward oxygen reduction reaction (ORR) was examined by both rotating (ring) disk electrode (R(R)DE) method single-cell proton exchange membrane fuel cells (PEMFCs). DFT calculations suggest that much...

Abstract The poor discharge and recharge efficiency demonstrated by lithium–air batteries renders the search for highly active inexpensive oxygen reduction evolution catalysts crucial to development of these energy‐storage conversion devices. Previous works have shown that manganese oxides are promising lithium–oxygen cathode catalysts, which is in agreement with their remarkable activities aqueous media. Motivated resembling catalytic behaviors, we prepared characterized a number oxide...