Multiple Redox Modes in the Reversible Lithiation of High-Capacity, Peierls-Distorted Vanadium Sulfide.

This is the author accepted manuscript. The final version is available from ACS via http://dx.doi.org/10.1021/jacs.5b03395Vanadium sulfide VS4 in the patronite mineral structure is a linear chain compound comprising vanadium atoms coordinated by disulfide anions [S2](2-). (51)V NMR shows that the material, despite having V formally in the d(1) configuration, is diamagnetic, suggesting potential dimerization through metal-metal bonding associated with a Peierls distortion of the linear chains. This is supported by density functional calculations, and is also consistent with the observed alternation in V-V distances of 2.8 and 3.2 Å along the chains. Partial lithiation results in reduction of the disulfide ions to sulfide S(2-), via an internal redox process whereby an electron from V(4+) is transferred to [S2](2-) resulting in oxidation of V(4+) to V(5+) and reduction of the [S2](2-) to S(2-) to form Li3VS4 containing tetrahedral [VS4](3-) anions. On further lithiation this is followed by reduction of the V(5+) in Li3VS4 to form Li3+xVS4 (x = 0.5-1), a mixed valent V(4+)/V(5+) compound. Eventually reduction to Li2S plus elemental V occurs. Despite the complex redox processes involving both the cation and the anion occurring in this material, the system is found to be partially reversible between 0 and 3 V. The unusual redox processes in this system are elucidated using a suite of short-range characterization tools including (51)V nuclear magnetic resonance spectroscopy (NMR), S K-edge X-ray absorption near edge spectroscopy (XANES), and pair distribution function (PDF) analysis of X-ray data.SB acknowledges Schlumberger Stichting Fund and European Research Council (EU ERC) for funding. JC thanks BK21 plus project of Korea. We thank Phoebe Allan and Andrew J. Morris, University of Cambridge, for useful discussions. We also thank Trudy Bolin and Tianpin Wu of Beamline 9-BM, Argonne National Laboratory for help with XANES measurements. The DFT calculations were performed at the UCSB Center for Scientific Computing at UC Santa Barbara, supported by the California Nanosystems Institute (NSF CNS-0960316), Hewlett-Packard, and the Materials Research Laboratory (DMR-1121053). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357

Structural and transport evolution in the Li_xAg₂V₄O₁₁ system

We investigated the effect of inserting lithium into Ag2V4O11 (ε-SVO) on the structure, electronic properties and redox committed by combining in situ XRD measurements, ESR spectroscopy and 4 probes DC conductivity coupled with thermopower measurements. The electrochemical discharge occurs in three consecutive steps above 2 V (vs. Li+/Li). The first one, between 0 x-SVO, has been ascribed to the V5+ reduction through a solid solution mechanism. This reduction competes with a Li+/Ag+ displacement reaction which leads to a structural collapse owing to the ionic radii mismatch between the withdrawn Ag+ and the inserted Li+. The silver reduction progresses continuously with two different slopes along two composition–potential plateaus at 2.81 V and 2.55 V. Finally, the reduction continues until we obtain an amorphous structure with V4+ and a ε of V3+. Although, the silver re-enters the structure during the subsequent recharge, the original structure is not recovered. The reduction of silver forming silver metal nano-clusters acts to increase the electronic conductivity from 3.8 × 10−5 S cm−1 to 1.4 × 10−3 S cm−1. In complement to this study, we also report on a low temperature hydro-(solvo)-thermal approach using HF(aq) as a mineralizer, which enables the synthesis of nano-sized ε-SVO particles that exhibit superior electrochemical performances compared to conventional particles synthesized by solid-state reaction

Ag4V2O6F2 (SVOF): A high silver density phase and potential new cathode material for implantable cardioverter defibrillators

The electrochemical reactivity of the cathode material Ag4V 2O6F2 (SVOF) versus lithium, with a particular emphasis on the lithium insertion mechanism, was studied by means of the complementary techniques in situ X-ray diffraction, electron paramagnetic resonance, and high-resolution transmisssion electron microscopy. This study confirms the initial reports of a high capacity for SVOF of 148 mAh/g above 3 V and that the reduction of silver above 3 V (vs Li+/Li0) leads to a loss of SVOF crystallinity until it becomes completely amorphous between the third and fourth lithiums inserted. Next, vanadium is reduced between 2.5 and 1.5 V (vs Li+/Li0) for the fifth and sixth lithiums inserted. In addition, the polarization within the cathode is significantly lower for the vanadium reduction than for the silver reduction. The silver metal morphologies consisted of nanoparticles (∼5 nm diameter) and dendrites and were both seen in samples of lithiated SVOF. © 2008 American Chemical Society

New positive-electrode materials for lithium batteries

Current research in the lithium battery field combines the development of new synthesis methods with the discovery cathode materials that exhibit high energy storage capacity and electrochemical stability. For example, Ag2V4O11, or silver vanadium oxide (SVO), is used commercially as a cathode material in primary lithium batteries for high rate applications, such as those used in implantable cardioverter defibrillators (ICDs). A long-term goal of the medical battery industry is to increase the capacity of the cathode above 3 V while maintaining electrode stability. Low temperature hydrothermal techniques offer new routes to transition metal oxide fluorides, for example the new high silver density material Ag4V2O6F2 (SVOF) which was synthesized recently. The electrochemical behavior of SVOF and the significant impact new materials such as SVOF may have on the future generation of primary lithium batteries for ICDs will be highlighted

Profesionalna tuberkuloza srednjeg uha umedicinske sestre: prikaz slučaja

This article presents a case of a 40-year-old female patient with a right-side middle ear tuberculosis. The patient was a nurse, who had worked at the Department of Pulmology, Clinical Hospital Rijeka for 17 years. The cause was infection with Mycobacterium tuberculosis while she assisted in bronchoscopy. The patient was referred to occupational medicine (OM) for confirmation of occupational disease immediately after surgery. The disease was confirmed as occupational by the Croatian Institute for Health Insurance of Health Protection at Work. During surgery a sample was taken for microbiological analysis. We did initial and control multislice computed tomography (MSCT) and control magnetic resonance imaging (MRI) of temporal bones 6 months after the surgery. The initial MSCT showed total mastoid cell shadowing without destruction, while the control image showed almost full recovery save for a few remaining shadowed cells. Adequately taken occupational history by an OM specialist can significantly shorten the time to diagnosis of a rare occupational illness that is often manifested by non-specific symptomsTuberkuloza srednjeg uha kao primarna bolest je rijetka. U ovom radu prikazana je 40-godišnja pacijentica, medicinska sestra, koja je radila Rijeci, u Hrvatskoj, i oboljela je od desnostrane tuberkulozne upale srednjeg uha. Razlog je bio kontakt s Mycobacterium tuberculosis za vrijeme asistiranja kod bronhoskopije. Cilj je rada upozoravanje na važnost medicine rada koja je odmah nakon primitka pacijentice započela proces priznavanja profesionalne bolesti. Nakon dobivanja suglasnosti Hrvatskog zavoda za zdravstveno osiguranje zaštite zdravlja na radu pacijentica je dobila status profesionalno oboljele osobe i sva prava koja joj iz toga proizlaze. Za vrijeme operacije srednjeg uha uzet je obrisak na mikrobiološku analizu. Učinjena je inicijalna i kontrolna višeslojna kompjutorizirana tomografi ja (MSCT) te magnetska rezonancija (MR) temporalnih kostiju nakon 6 mjeseci liječenja. Mikrobiološka analiza bila je pozitivna na M. tuberculosis. Inicijalni MSCT pokazao je potpuno zasjenjenje celula mastoida bez destrukcije, a kontrolna snimka gotovo potpunu sanaciju sa zasjenjenjem tek pokoje celule, dok MR pokazuje porast signala kod malobrojnih celula. Dobro uzeta radna anamneza od strane medicine rada može znatno skratiti vrijeme dijagnosticiranja rijetkih profesionalnih bolesti, koje često imaju nespecifi čne simptome. Nadalje, pokretanje postupka te priznavanje profesionalne bolesti značajno je za adekvatni status i liječenje osoba oboljelih na radu