Task-irrelevant stimuli reliably boost phasic pupil-linked arousal but do not affect decision formation.

The arousal systems of the brainstem, specifically the locus coeruleus-noradrenaline system, respond "phasically" during decisions. These central arousal transients are accompanied by dilations of the pupil. Mechanistic attempts to understand the impact of phasic arousal on cognition would benefit from temporally precise experimental manipulations.

Lithium Manganese Sulfates as a New Class of Supercapattery Materials at Elevated Temperatures.

To make supercapattery devices feasible, there is an urgent need to find electrode materials that exhibit a hybrid mechanism of energy storage. Herein, we provide a first report on the capability of lithium manganese sulfates to be used as supercapattery materials at elevated temperatures. Two compositions are studied: monoclinic LiMn(SO) and orthorhombic LiMn(SO), which are prepared by a freeze-drying method followed by heat treatment at 500 °C.

Oxygen-Storage Materials to Stabilize the Oxygen Redox Activity of Three-Layered Sodium Transition Metal Oxides.

To double the energy density of lithium- and sodium-ion batteries there is a need to activate simultaneously cationic and anionic redox reactions at the intercalation-type electrodes. In contrast to the cationic redox activity, the oxygen redox activity enforces an enhancement in the surface reactivity of the oxides leading to their poor reversibility and cycling stability. Herein, we propose a new concept to stabilize oxygen redox activity by using oxygen-storage materials as an efficient buffer supplying and receiving oxygen during alkali ion intercalation.

Hybrid Li/Na Ion Batteries: Temperature-Induced Reactivity of Three-Layered Oxide (3-NaNiMgMnO) Toward Lithium Ionic Liquid Electrolytes.

Hybrid metal ion batteries are perceived as competitive alternatives to lithium ion batteries because they provide better balance between energy/power density, battery cost, and environmental requirements. However, their cycling stability and high-temperature storage performance are still far from the desired. Herein, we first examine the temperature-induced reactivity of three-layered oxide, 3-NaNiMgMnO, toward lithium ionic liquid electrolyte upon cycling in hybrid Li/Na ion cells.

Redox properties of alluaudite sodium cobalt manganese sulfates as high-voltage electrodes for rechargeable batteries.

Alluaudite sulfates are predicted to be high-voltage electrodes for lithium- and sodium-ion batteries. Herein, we provide the first experimental evidence for the operation of sodium cobalt-manganese sulfate, Na2+2δ(Co0.63Mn0.

Selective sodium intercalation into sodium nickel-manganese sulfate for dual Na-Li-ion batteries.

Double sodium transition metal sulfates combine in themselves unique intercalation properties with eco-compatible compositions - a specific feature that makes them attractive electrode materials for lithium and sodium ion batteries. Herein, we examine the intercalation properties of novel double sodium nickel-manganese sulfate, Na2Ni1/2Mn1/2(SO4)2, having a large monoclinic unit cell, through electrochemical and ex situ diffraction and spectroscopic methods. The sulfate salt Na2Ni1/2Mn1/2(SO4)2 is prepared by thermal dehydration of the corresponding hydrate salt Na2Ni1/2Mn1/2(SO4)2·4H2O having a blödite structure.

Combined use of EPR and Na MAS NMR spectroscopy for assessing the properties of the mixed cobalt-nickel-manganese layers of P3-NaCoNiMnO.

Knowledge on the formation of mixed transition metal layers on lithium and sodium transition metal oxides, Li/Na(Co,Ni,Mn,)O, determines the ability to control their electrochemical properties as electrode materials in alkaline ion batteries. Taking this into account, herein we combine the EPR and Na MAS NMR spectroscopic techniques to gain insights into the structural peculiarities of the mixed cobalt-nickel-manganese layers of NaCoNiMnO with a three-layer stacking (P3-type) structure. Two types of compositions are examined where diamagnetic Co and paramagnetic Ni and Mn are stabilized: NaCoNiMnO and NaNiMnO.

Layered P3-NaxCo1/3Ni1/3Mn1/3O2 versus Spinel Li4Ti5O12 as a Positive and a Negative Electrode in a Full Sodium-Lithium Cell.

The development of lithium and sodium ion batteries without using lithium and sodium metal as anodes gives the impetus for elaboration of low-cost and environmentally friendly energy storage devices. In this contribution we demonstrate the design and construction of a new type of hybrid sodium-lithium ion cell by using unique electrode combination (Li4Ti5O12 spinel as a negative electrode and layered Na3/4Co1/3Ni1/3Mn1/3O2 as a positive electrode) and conventional lithium electrolyte (LiPF6 salt dissolved in EC/DMC). The cell operates at an average potential of 2.

P3-Type Layered Sodium-Deficient Nickel-Manganese Oxides: A Flexible Structural Matrix for Reversible Sodium and Lithium Intercalation.

Sodium-deficient nickel-manganese oxides exhibit a layered structure, which is flexible enough to acquire different layer stacking. The effect of layer stacking on the intercalation properties of P3-Na Ni Mn O (x=0.50, 0.

A fractal-like electrode based on double-wall nanotubes of anatase exhibiting improved electrochemical behaviour in both lithium and sodium batteries.

An anatase nanotube array has been prepared with a special morphology: two concentric walls and a very small central cavity. The method used here to achieve the double-wall structure is a single-step anodization process under a voltage ramp. Thanks to this nanostructure, which is equivalent to a fractal electrode, the electrochemical behaviour is improved, and the specific capacity is higher in both lithium and sodium cells due to pseudocapacitance.

High-intensity ultrasonication as a way to prepare graphene/amorphous iron oxyhydroxide hybrid electrode with high capacity in lithium battery.

The preparation of graphene/iron oxyhydroxide hybrid electrode material with very homogeneous distribution and close contact of graphene and amorphous iron oxyhydroxide nanoparticles has been achieved by using high-intensity ultrasonication. Due to the negative charge of the graphene surface, iron ions are attracted toward the surface of dispersed graphene, according to the zeta potential measurements. The anchoring of the FeO(OH) particles to the graphene layers has been revealed by using mainly TEM, XPS and EPR.

Correlations between lithium local structure and electrochemistry of layered LiCo(1-2x)Ni(x)Mn(x)O2 oxides: 7Li MAS NMR and EPR studies.

Advanced (7)Li MAS NMR technologies and high frequency EPR are combined to identify structural motifs and their relation to electrochemical properties of layered lithium-cobalt-nickel-manganese oxides LiCo1-2xNixMnxO2 (0 < x ≤ 0.5) used as cathode materials in lithium ion batteries. Structural-chemical shift regularities were established by systematic variation of the ratio of diamagnetic Co(3+) to paramagnetic Ni/Mn ions with variable valences.

Lithium storage mechanisms and effect of partial cobalt substitution in manganese carbonate electrodes.

A promising group of inorganic salts recently emerged for the negative electrode of advanced lithium-ion batteries. Manganese carbonate combines low weight and significant lithium storage properties. Electron paramagnetic resonance (EPR) and magnetic measurements are used to study the environment of manganese ions during cycling in lithium test cells.

Local structure of Mn4+ and Fe3+ spin probes in layered LiAlO2 oxide by modelling of zero-field splitting parameters.

The zero-field splitting parameters (ZFS) of Mn(4+) and Fe(3+) ions in LiAlO(2) with a layered structure are analyzed experimentally and theoretically by using high-frequency electron paramagnetic resonance spectroscopy, Neuman superposition model (NSM), DFT and multiconfigurational calculations. The interpretation of ZFS is based on the comparison of the experimentally determined values with the calculated ones. This approach allows assessing the performance of different methods for computation of ZFS of Fe(3+) and Mn(4+) in layered oxide matrices.

Facile synthesis of LiMnPO4 olivines with a plate-like morphology from a dittmarite-type KMnPO4·H2O precursor.

Dittmarite-type compound KMnPO(4)·H(2)O was used as a new precursor for the synthesis of nanostructured LiMnPO(4) phospho-olivines with a plate-like morphology at low temperature (about 200 °C) and a short reaction time (90-180 min). The dehydration of KMnPO(4)·H(2)O was studied by DTA and TG analysis. Structural and morphological characterization of both KMnPO(4)·H(2)O and LiMnPO(4) was performed by powder XRD, SEM and TEM analyses.

High-frequency electron paramagnetic resonance analysis of the oxidation state and local structure of Ni and Mn ions in Ni,Mn-codoped LiCoO(2).

High-frequency electron paramagnetic resonance (HF-EPR) spectroscopy was employed to examine the oxidation state and local structure of Ni and Mn ions in Ni,Mn-codoped LiCoO(2). The assignment of EPR signals was based on Mg,Mn-codoped LiCoO(2) and Ni-doped LiCoO(2) used as Mn(4+) and low-spin Ni(3+) EPR references. Complementary information on the oxidation state of transition-metal ions was obtained by solid-state (6,7)Li NMR spectroscopy.

Local coordination of Fe(3+) in layered LiCo(1-y)Al(y)O(2) oxides determined by high-frequency electron paramagnetic resonance spectroscopy.

The local coordination of Fe(3+) spin probes in trigonal LiAl(y)Co(1-y)O(2) was studied using high-frequency electron paramagnetic resonance spectroscopy. This technique allows the determination of Fe(3+) ions in respect to axial and rhombic zero-field splitting parameters (ZFS). After the progressive replacement of Co by Al, the axial D parameter of Fe(3+) increases from +0.