Olivine Research Articles

Implications of Hf Isotopes for the Evolution of the Mantle Source of Magmas Associated with the Giant El Teniente Cu-Mo Megabreccia Deposit, Central Chile

We have determined the Hf isotopic compositions of 12 samples associated with the giant El Teniente Cu-Mo megabreccia deposit, central Chile. The samples range in age from ≥8.9 to 2.3 Ma and provide information about the temporal evolution of their magmatic sources from the Late Miocene to Pliocene. Together with previously published data, the new analysis indicates a temporal decrease of 10 εHf(t) units, from +11.6 down to +1.6, in the 12.7 m.y. from 15 to 2.3 Ma. These variations imply increasing incorporation of continental crust through time in the magmas that formed these rocks. The fact that the samples include mantle-derived olivine basalts and olivine lamprophyres suggests that these continental components were incorporated into their mantle source, and not by intra-crustal contamination (MASH). We attribute the increase, between the Middle Miocene and Pliocene, of crustal components in the subarc mantle source below El Teniente to be due to increased rates of subduction erosion and transport of crust into the mantle. The deposit formed above a large, long-lived, vertically zoned magma chamber that developed due to compressive deformation and persisted between ~7 to 4.6 Ma. Progressively more hydrous mantle-derived mafic magmas feed this chamber from below, providing heat, H2O, S and metals, but no unique “fertile” Cu-rich magma was involved in the formation of the deposit. As the volume of these mantle-derived magmas decreased from the Late Miocene into the Pliocene, the chamber crystallized and solidified, producing felsic plutons and large metal-rich magmatic-hydrothermal breccias that emplaced Cu and S into the older (≥8.9 Ma) mafic host rocks of this megabreccia deposit.

Lyotropic Liquid Crystalline Mesophases Made of Salt-Acid-Surfactant Systems for the Synthesis of Novel Mesoporous Lithium Metal Phosphates.

Mesoporous lithium metal phosphates are an important class of materials for the development of lithium ion batteries. However, there is a limited success in producing mesoporous lithium metal phosphates in the literature. Here, a lyotropic liquid crystalline (LLC) templating method was employed to synthesize the first examples of LiMPO4 (LMP) of Mn(II), Co(II), and Ni(II). A homogeneous aqueous solution of lithium and transition metal nitrate salts, phosphoric acid (PA), and surfactant (P123) can be spin coated or drop-cast coated over glass slides to form the LLC mesophases which can be calcined into mesoporous amorphous LMPs (MA-LMPs). The metal salts of Mn(II), Co(II) and Ni(II) produce MA-LMPs that crystallize into olivine structures by heat treatment of the LLC mesophase. The Fe(II) compound undergoes air oxidation. Therefore, both Fe(II) and Fe(III) precursors produce a crystalline Li3 Fe2 (PO4 )3 phase at over 400 °C. The MA-LMPs show no reactivity towards lithium, however the crystalline iron compound exhibits electrochemical reactivity with lithium and a good electrochemical energy storage ability using a lithium-ion battery test.

Investigation of Olivine and Nasicon Structured Phosphates As Potential Cathode Materials for Magnesium Ion Batteries

The depletion of fossil fuel reserves as well as climate change motivate the development of new environmentally-friendly technologies for energy generation, storage, and consumption. Robust energy storage devices must be developed to meet the growing demand for portable electronics (i.e. laptops and mobile phones), electric vehicles and energy storage systems. Although lithium-ion batteries have mostly driven the revolution in modern electronics for the last three decades, new chemistries for “next-generation” batteries are currently under research and development. These new technologies are tasked with delivering better performance (capacity and current capability) at low cost while being environmentally friendly. In order to fill the gap between the current state of the art and future energy storage needs, magnesium is considered to be a possible alternative to lithium due to its natural abundancy and low toxicity. Furthermore, due to the divalent nature of the Mg2+ cations, a high theoretical volumetric capacity of 3833 mA h cm-3 can be attained if pure magnesium is used as the anode material.1 Additionally, since magnesium deposition takes place without dendrite formation on the Mg-metal anode surface, the Mg-cell is expected to be considerably safer than comparable cells based on lithium. Despite these positive attributes, the development of magnesium secondary batteries is hindered by the slow solid-state diffusion of Mg2+ ions into the cathode lattice. In this work, this issue is explored by synthesising and characterising two different phosphate-based systems to investigate their suitability as cathode materials for Mg-ion batteries, with phosphates chosen due to their structural stability and safety.2,3 The NASICON and olivine phosphates are known for their high conductivity in lithium-based systems and were selected here as potential hosts for Mg2+intercalation. NASICON compounds are usually reported as cathode or solid electrolyte materials for Li and Na-ion batteries, but there is a lack of reproducible data for Mg ion technologies. Therefore, the NASICON-structured Mg0.5Ti2(PO4)3 compound was selected for synthesis and further electrochemical characterisation. Additionally, the olivine-related (Mg0.5Ni0.5)3(PO4)2 was investigated as a novel cathode active material for the first time. This compound was chosen because of its open crystal structure, which is potentially favourable for magnesium ion diffusion. In parallel, V2O5 was used as a reference cathode active material in order to validate the electrochemical set-up, which is non-trivial for Mg chemistry. Mg0.5Ti2(PO4)3 and (Mg0.5Ni0.5)3(PO4)2 were obtained by the solid-state method and their crystal structures and phase purities were determined by Rietveld analysis of X-ray powder diffraction data. Scanning electron microscopy (SEM) was performed to analyse the particle morphologies, with particle sizes and porosities characterised by dynamic light scattering (DLS) and nitrogen adsorption (BET) techniques, respectively. Both cyclic voltammetry and galvanostatic cycling with potential limitation were carried out in order to investigate the insertion-extraction mechanism of Mg2+ ions. Ex-situ powder X-ray diffraction and SEM confirmed the crystal structures and particle morphologies, respectively, of the cathode active materials after cycling, while X-ray photon electron spectroscopy (XPS) was used to monitor changes in the oxidation state of the transition metal cation. Our results show that cells based on Mg metal anodes utilising Mg(ClO4)2 in acetonitrile as electrolyte suffer from the creation of a passivation layer leading to poor performance. In order to address this problem, activated carbon was used to replace metallic magnesium as the anode material, with the electrolyte acting as the main source for magnesium ions. The use of a carbon-based anode is seen to eliminate the passivation layer problem and improve capacity and cell cyclability. References H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, D. Aurbach, Energy Environ. Sci., 2013, 6, 2265–2279; P. Canepa, G. Sai Gautam, D. C. Hannah, R. Malik, M. Liu, K. G. Gallagher, K. A. Persson, G. Ceder, Chem. Rev., 2017,117, 4287–4341; B. Kang, G. Ceder, Nature, 2009,458, 190.

Eruptive Activity on the Western Flank of Piton de la Fournaise (La Réunion Island, Indian Ocean): Insights on Magma Transfer, Storage and Evolution at an Oceanic Volcanic Island

AbstractPetrological and geochemical (major element, trace element, Sr–Nd isotope) data for recent (<5 kyr old) basalts that sporadically erupt on the western flank of Piton de la Fournaise (PdF), one of the most active volcanoes on Earth, allow the tracking of magma transfer and evolution from mantle to crustal depths. In the western peripheral area of PdF we document the broadly synchronous eruptions of (1) primitive olivine and olivine–clinopyroxene transitional basalts with tholeiitic affinity that are closely associated in space with (2) transitional olivine basalts with alkaline affinity, and (3) hybrid lavas, intermediate between the ‘alkaline’ and the ‘tholeiitic’ end-members. The composition of the latter overlaps with that of the lavas frequently erupted from the conduit system feeding the main summit cone. AlphaMELTS modelling, and fluid inclusion and clinopyroxene barometry, constrain the conditions of magma storage at 10–30 km, and the ascent of magma from the upper mantle to the shallow crustal plumbing system. Variable degrees of mantle melting, together with minor source heterogeneity and contamination with cumulate-derived partial melts, contribute to the diversity of PdF magmas. However, all these processes do not represent the dominant factors that produce the large variability we found in major element composition. Indeed, the composition of basalts erupted from PdF peripheral centers is strongly controlled by polybaric olivine–clinopyroxene fractionation at pressures higher than 3 kbar. Crystal textures and geochemical modelling suggest that fast magma ascent is critical to prevent clinopyroxene dissolution. Conversely, long-lasting magma stagnation promotes pyroxene resorption and magma differentiation. ‘Central’ eruptions occurring close to the PdF summit cone emit variably more evolved melts, which result from olivine–clinopyroxene–plagioclase differentiation at intermediate–shallow pressure (<3 kbar and in most cases <1 kbar). Deep and extensive magma mixing before injection into the crustal magma conduit system, located below the summit region, results in the apparent homogeneity of basalts erupted from the central area. As regards ‘peripheral’ eruptions, deep-seated stagnation of basaltic melts and differentiation at the mantle–crust transition zone (c. 4 kbar) produces a range of magma compositions. We demonstrate that rapid magma ascent from deep-seated reservoirs can bypass the central plumbing system. The eruptions of these magmas both in the central area and on the densely populated flanks have major consequences in terms of volcanic hazard at PdF.

Volcanogenic processes and petrogenesis of the early Pleistocene andesitic-dacitic Maungatautari composite cone, Central Waikato, New Zealand

ABSTRACTMaungatautari is an extinct, andesitic-dacitic composite cone situated 35 km southwest of Hamilton, New Zealand. This study examines the volcanic history and petrologic evolution of Maungatautari using field mapping, petrography of pyroclastic successions and lavas, and whole rock and isotope analyses of selected lavas. Lavas consist of non-vesicular labradorite, pyroxene and hornblende andesites and dacites. A small cone of olivine basalt is located at Kairangi, 7 km to the northwest of the Maungatautari trig. Whole rock geochemical and strontium and neodymium analyses demonstrate that these lavas were derived from at least three distinct mantle-melt sources. Mass-wasting processes continue to shape the mountain post volcanic activity and include catastrophic failure of the north-eastern flank which produced a 0.28 km3 rock avalanche deposit. This study considers Maungatautari to reflect andesitic-dacitic arc volcanism occurring within the upper North Island c. 2 Ma.

Solution combustion synthesis and electrochemical properties of yttrium-doped LiMnPO4/C cathode materials for lithium ion batteries

Phospho-olivine pristine LiMnPO4/C and yttrium-substituted LiMn1–xYxPO4/C (x = 0, 0.01, 0.03, 0.05) were synthesized by a solution combustion method. The effects of Y-doped on structure, morphology and electrochemical performances were investigated. From powder X-ray diffraction pattern, all substituted materials adopt an identical structure to that of the LiMnPO4 olivine structure, suggesting that the yttrium ion was well incorporated into the crystal lattice, without any changes in the host crystal structure. The electrochemical impedance spectroscopy provides clearly that yttrium-substituting reduces the charge transfer impedance and improves the lithium ion diffusion through the structure. When x = 0.01, the material shows an excellent capacity and stability during charge/discharge process. The initial specific discharge capacity can reach up to 156.84 mAh/g at C/20, with a coulombic efficiency of about 96.11%, which is 14% higher than that of the pristine material. The results confirm that the cyclic stability and the electrochemical performances of LiMnPO4/C are highly improved by Y-doping.

Microwave dielectric properties of low temperature co-fired ceramics LiMg1-xAxPO4 (A = Mn, Ca, 0.02 ≤ x ≤ 0.08)

Abstract Novel low-firing microwave dielectric ceramics LiMg1-xAxPO4 (A = Mn, Ca, 0.02 ≤ x ≤ 0.08) with orthorhombic olivine structure were synthesized using the solid-state reaction method. The effects of Mn2+ and Ca2+ on the phase composition, sintering behaviors and microwave dielectric properties of LiMgPO4 ceramics were studied in detail. To some extent, Mn2+ and Ca2+ reduced the sintering temperature of LiMgPO4 ceramics and improved its properties. Both systems exhibited excellent comprehensive properties (LiMg0.96Mn0.04PO4: er = 6.54, Q*f = 84,343 GHz, τf = −44.9 ppm/°C, Ts (optimum sintering temperature) = 875 °C; LiMg0.94Ca0.06PO4: er = 6.96, Q*f = 88,968 GHz, τf = −44.7 ppm/°C, Ts = 800 °C). In conclusions, novel systems in this work would be promising candidates for low-temperature cofired ceramic (LTCC) applications.

Spectral Characteristics of Hydrothermal Alteration in Zuru, NW Nigeria

This study demonstrated the ability of a Landsat-8 OLI multispectral data to identify and delineate hydrothermal alteration zones around auriferous prospects within the crystalline basement, North-western Nigeria. Remote sensing techniques have been widely used in lithological, structural discrimination and alteration rock delineation, and in general geological studies. Several artisanal mining activities for gold deposit occur in the surrounding areas within the basement complex and the search for new possible mineralized zones have heightened in recent times. Systematic Landsat-8 OLI data processing methods such as colour composite, band ratio and minimum noise fraction were used in this study. Colour composite of band 4, 3 and 2 was displayed in Red-Green- Blue colour image to distinguish lithologies. Band ratio image displayed in red was used to highlight ferric-ion bearing minerals (hematite, goethite, jarosite) associated with hydrothermal alteration, band ratio image displayed in green was used to highlight ferrous-ion bearing minerals such as olivine, amphibole and pyroxenes, while ratio image displayed in blue was used to highlight clay minerals, micas, talc-carbonates, etc. Band rationing helped to reduce the topographic illumination effect within images. The result of this study showed the distribution of the lithological units and the hydrothermal alteration zone which can be further prospected for mineral reserves.

Performance of Vanadium Doped and Carbon Bamboo/Carbon Black Coated Lithium Iron Phosphate for Battery Cathode

Synthesis of lithium iron phosphate (LiFePO4) via wet chemical followed by a hydrothermal method has been carried out. The preparation of LiFePO4 was begun with the precursor of LiOH, NH4H2PO4, and FeSO4.7H2O mixed stoichiometrically. After the synthesis, LiFePO4 was doped using vanadium and then coated using two types of carbon sources, i.e. carbon black blended with activated carbon pyrolyzed from bamboo, through a solid-state reaction. The materials were mixed using a ball-mill and subsequently characterized using a thermal analyzer (STA) to determine the sintering temperature. The result shows that LiFePO4 formation temperature is at 639°C. The sintering process was performed for 4 hours and the characterization was done using X-ray diffraction (XRD) and electron microscope (SEM) equipped with energy dispersive x-ray spectroscopy (EDX). The electrochemical impedance spectroscopy (EIS) testing was performed to show the conductivity of the formed materials. XRD result showed that LiFePO4/V/C phase has formed with an olivine structure, while the SEM result showed fair distribution and small particle size with some agglomerated microstructures. The EIS results showed that carbon coating on the active material increases the conductivity, whereas the addition of vanadium increases the conductivity of up to 5 wt.% vanadium but decreases at 7 wt.% vanadium.

A faltering origin for the Acheulean? Technological and cognitive implications from FLK West (Olduvai Gorge, Tanzania)

The discovery in FLK West lowermost level 6 (Olduvai Gorge, Tanzania) of a massive and symmetrical handaxe, at odds both with the other LCT specimens so far unearthed from this site and with the technological traits commonly reported for the earliest Acheulean ca. 1.7 Ma, challenges the hypothesis of a gradual development of technological and cognitive qualities during the Acheulean. This thought-provoking specimen points to a less sharp difference between the first and later phases of the Early Acheulean (i.e. between ca. 1.7 and 1.2 Ma) and supports a somewhat punctuated flourishing of the handaxe technical and cognitive conceptualization. In this regard, this paper provides a detailed descriptive study of the large olivine basalt handaxe, in the framework of both the FLK West L6 lithic collection and the LCT shaping strategies. This analysis includes a morphometric description of the specimen and a comprehensive analysis of the knapping and shaping sequencing, through a diacritical study. It also includes a techno-functional assessment of the final design and symmetry. Finally, this paper examines some of the most significant implications of this large tool for our current views on temporal divisions within the African Acheulean and the cognitive abilities of the individual that made it.

Evolution of parental melts of alkali ultrabasic intrusive massives of Maimecha-Kotui Province (Polar Siberia)

Computational modeling based on data on the compositions of melt inclusions in chrome-spinelids using the COMAGMAT [12] and PETROLOG [11] programs indicates the similarity of the parent melt of meimechites [4] with the picritic magma of the Gulinsky massif. Experimental data on the inclusions confirm this conclusion, showing the reliability of the actually calculated trends in the fractionation of ultrabasic melts. In general, the calculations showed that the crystallization of olivine from the high-magnesium pyrite melt occurred in the temperature range of 1510–1260 ° C, mainly at a pressure of 6–7 kbar. At the same time, the melt evolves and approaches its composition to olivine basalt, from which, starting from 1200 ° C, clinopyroxene mainly crystallizes with enrichment of the residual melt with alkalis, rare and rare-earth elements. The similarity of the compositions of the parental melts for meimechites and Gulinsky pluton rocks and the proximity of P – T parameters of their evolution indicates a possible genetic relationship of these magmatic formations.

Study of the adsorption mechanism on the surface of a ceramic nanomaterial for gaseous Hg(II) removal.

Stable Hg(II)-containing flue gas has been successfully simulated by the plasma oxidation of Hg(0), and an effective solution for Hg(0) mercury fumes was obtained by combining the plasma with a ceramic nanomaterial. Characterization tests showed that the ceramic nanomaterial was mainly composed of silicon dioxide (SiO2) with other minor constituents, including potassium mica (KAl3Si3O11), iron magnesium silicate (Fe0.24Mg0.76SiO3) and dolomite (CaMg(CO3)2). The nanomaterial had many tube bank structures inside with diameters of approximately 8-10nm. The maximum sorption capacity of Hg(II) was 5156μg/g, and the nanomaterial can be regenerated at least five times. During the adsorption, chemical adsorption first occurred between Hg(II) and sulfydryl moieties, but these were quickly exhausted, and Hg(II) was then removed by surface complexation and wrapped into Fe moieties. The pseudo-first-order kinetic model and the Langmuir equation had the best fitting results for the kinetics and isotherms of adsorption. This work suggests that the ceramic nanomaterial can be used as an effective and recyclable adsorbent in the removal of gaseous Hg(II).

Reactive melt migration controls the trace element budget of the lower oceanic crust: insights from the troctolite-olivine gabbro association of the Pineto Ophiolite (Corsica, France)

The Pineto gabbroic sequence is a ~ 1.5 km-thick crustal section similar to those forming the oceanic core complexes at modern slow-spreading ridges. The sequence is subdivided into two sectors displaying different bulk compositions. The deeper sector consists of troctolites, with minor olivine gabbros and sparse olivine-rich troctolite intercalations. We carried out a thorough chemical characterization, including minerals and bulk rocks, of the troctolite/olivine gabbro association. Although the whole-rock compositions are mainly controlled by mineral proportions, the whole-rock variability of some minor (e.g., Cr, Ni) and trace (e.g., Y, REE) elements reveals formation by open-system crystallization processes. This interpretation is supported by the trace element mineral compositions. The incompatible trace element signature of clinopyroxene in the different rock types is nearly undistinguishable, whereas olivine and plagioclase show substantial variability of trace element compositions. In particular, olivine and plagioclase from the Ol-gabbros are typically depleted in incompatible elements compared to olivine and plagioclase from the troctolites. This chemical variability attests that fractional crystallization alone cannot have determined the compositions of these rocks, but requires an open system process where melts migrate and chemically interact with pre-existing crystal mushes leading to the redistribution of major and trace elements throughout the cumulate pile.

Deformation history of ultra high-pressure ophiolitic serpentinites in the Zermatt-Saas Zone, Créton, Upper Valtournanche (Aosta Valley, Western Alps)

Detailed multiscale structural analyses and mapping (1:20 scale) integrated with petrological investigation were used to study a portion of the Zermatt-Saas serpentinites that crop out in upper Valtournanche (north-western Italy). Results are synthesized in a foliation trajectory map that displays the transposed original lithostratigraphy of a serpentinite body exposed at Creton. The serpentinite body comprises magnetite sheets and rare, decimetre-thick, diopsidite layers and lenses. Moreover, veins and aggregates of Ti-chondrodite and Ti-clinohumite, olivine-rich layers and lenses, veinlets of olivine, and layers of dark pyroxenite are embedded in the serpentinites. Serpentinites and associated rocks record three relative age groups of ductile structures: D1 consists of rare folds and S1 foliation; D2 is a group of isoclinal folds and a very pervasive foliation (S2), which is the dominant structure; D3 includes a crenulation and shear zones affecting S2. The detailed meso-structural and microstructural analyses allowed individuating the metamorphic environment of successive deformation stages and correlating the resulting tectono-metamorphic investigation with those already inferred in surrounding areas. In addition, metre- to submillimetre-sized pre-D2 structural, mineralogical, and textural relics have been clearly identified in spite of the strong transposition imposed during the development of S2 high pressure - ultra-high pressure foliation.

Effect of spray drying technological conditions on the performance of LiFePO4/C cathode materials with high energy density

Lithium iron phosphate/carbon (LiFePO4/C) composites with high energy density were synthesized by wet ball milling, spray drying, and carbothermal reduction method. The effect of spray drying technological conditions on the performance of LiFePO4/C composites was systematically investigated. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge tests, etc. The results show that all as-prepared LiFePO4/C composites have a well-ordered olivine structure and spherical morphology. Compared with centrifugal spray drying technology, LiFePO4/C prepared by pressure spray has a smaller particle size and exhibits more uniform particle size distribution as well as better electrochemical performance. However, as the particle size of LiFePO4/C microspheres is decreased, the sphericity of particles becomes worse and tap density of materials steps down, resulting in poor processability in 14500 cylindrical battery.

The Effects of Nickel Doping on the Structure of LiNi<sub>x</sub>Fe<sub>1-x</sub>PO<sub>4</sub>/C Cathode Material

This study has been successfully synthesized Nickel (Ni)-doped olivine-type LiNixFe1-xPO4/C with x= 0, 0.01, 0.02, 0.03 as cathode materials, using the solid-state reaction method was in order to investigate the effect on the structure and morphology. The precursor material of ion Ferro (Fe) is used natural material from ironstone of Tanah Laut Kalimantan Indonesian which combined with proanalis materials. The X-Ray Diffraction (XRD) patterns on the structure magnetite iron have shown that single phase of Fe3O4 and the patterns of structure LiNixFe1-xPO4/C indicated that doping Ni2+ have shown the orthorhombic structure with space group Pnma for all LiNixFe1-xPO4/C samples. Base on Rietveld method by Rietica software, the formation of phase resulted in olivine structure except at the concentration x = 0.02 and 0.03 have a second phase, that is nasicon structure with a smaller percentage than olivine structure. The general condition, coating carbon on LiNixFe1-xPO4/C particles by solid state reaction can be perfect which demonstrate the homogeneous existence of carbon on the surface of LiNixFe1-xPO4/C particles shown by images Scanning Electron Microscopy (SEM). The increased doping of Ni ions causing the Fe ions to decrease base on Energy Dispersive X-Ray Spectroscopy (EDS) observations.

Electrochemical Properties of Low Co-Containing Layered Oxide Cathodes Viewing from Structural, Defect and Processing Variations

Layered oxides containing transition metal ions are known to exhibit higher capacities than ones with spinel or olivine structures. However, higher charging capacity means the creation of more ionic/electronic defects in both cation and/or anion sublattices of layered structure. As a result, their structural and electrochemical properties are strongly affected by the formation and/or elimination of these defects. Moreover, the existing defects in layered oxides are typically determined by the condition of fabrication processes, for instance the oxygen partial pressure. The capacity fading observed in layered oxides is typically caused by the phase transformation of cycled layered oxides. In addition, the structural instability of layered oxides may be due to repeated formation/elimination of large amount of defects. Doping of aliovalent ions has been widely used for control of defects through charge compensation mechanism. Thus, the main objective of this work to investigate (i)the structural/electrochemical properties, (ii) charging/discharging/cycling behaviour (ii) effect of aliovalent doping on high Ni/low Co-containing layered oxides. In this study, the electrical/electrochemical/structural properties of layered oxide containing 80% Ni in transition metal layer are investigated. Layered oxides are fabricated using either solid state reaction or co-precipitation techniques. Ni content in is fixed at 80% in the transition metal ion layers in these cathode materials, the variation in electrochemical properties will be caused by the minor elements/dopants such as Mn and Al. First, the electrical measurement of layered oxides are conducted using sintered disc. Assembled cells using above-mentioned cathode and Li anode with desired liquid electrolyte will be tested and cycled. XPS, SEM and XRD analyses will be conducted on as-assembled as well as cycled cells. The analysed results will be illustrated based on the chemical characteristics of doping ions and the accompanying defects created.

Development of LiFePO4/FePO4 Electrode for Electro-Osmotic Pump using Li+ Migration

Olivine structure of LiFePO4 (LFP) is one of the most commonly used materials in aqueous rechargeable lithium batteries (ARLBs), and can store and release charge through the insertion/de-insertion of Li+ between LFP and FP. We have fabricated LFP and LFP/FP electrodes on titanium paper and studied their electrochemical properties in 2 M Li2SO4. The LFP/FP electrode was determined to be a suitable electrode for electo-ostmotic pump (EOP) in terms of efficiency in water and 0.5 mM Li2SO4 solution. Experiments to determine the effect of cations and anions on the performance of EOP using LFP/FP electrode have shown that Li+ is the best cation and that the anion does not significantly affect the performance of the EOP. As the concentration of Li2SO4 solution was increased, the current increased. The flow rate peaked at 4.8 μL/30 s in 1.0 mM Li2SO4 solution and then decreased. When the EOP was tested continuously in 1.0 mM Li2SO4 solution, the EOP transported approximately 35 mL of fluid while maintaining a stable flow rate and current for 144 h. Keywords: Electro-osmotic pump (EOP), Aqueous rechargeable lithium-ion battery (ARLB), Lithium iron phosphate (LFP), Electrode, Lithium ion (Li+)

Synthesis of Nanosilica via Olivine Mineral Carbonation under High Pressure in an Autoclave

Synthesis of Nanosilica via Olivine Mineral Carbonation under High Pressure in an Autoclave

Solution combustion synthesis of LiMnPO4/C cathode material: The effect of four fuel sources on the electrochemical performances

Nanocrystalline LiMnPO4/C cathode material was successfully prepared by the solution combustion method using Urea, Glycine, Starch and PEG-10000 as fuel agents and Starch as carbon-coating source. The as-prepared samples are characterized XRD, SEM, TEM and Raman spectroscopy. According to X-ray diffraction results, all synthesized materials adopt the same olivine structure, suggesting that fuel sources have no effect on the phase purity, however, it can affect the electrochemical performances. The investigation reveals that LiMnPO4/C material obtained with glycine, as fuel source, has a smaller crystallite size and a lower microstrain value than the other samples. The electrochemical impedance spectroscopy confirms that glycine use as a fuel agent can decrease the charge transfer resistance and enhances the lithium ion diffusion. The initial discharge capacity can reach up to 127 mAh g−1 at 0.05 C between 2.5 and 4.5 V, with a coulombic efficiency of about 82%. The results suggest that fuel choice is a crucial parameter in order to improve the performance of LiMnPO4 cathode material.