Transmission Line Model Impedance Analysis of Lithium Sulfur Batteries: Influence of Lithium Sulfide Deposit Formed During Discharge and Self-Discharge

The effect of Li2S deposition on the impedance response of Li-S battery cells is investigated using a simplified cell design, systematic impedance spectroscopy measurements combined with transmission line modeling, and a complementary microscopy analysis. Glassy carbon cathodes are employed to build and validate the proposed transmission line model, which is later on employed to investigate the effect of various parameters of Li2S deposit (coverage, thickness, porosity) on cell’s impedance. Among others, the model is applied to study the effect of discharge and self-discharge. Finally, the simplified planar cathode is exchanged with a more conventional mesoporous carbon cathode to determine the effect of Li2S deposition on the impedance of a commercially viable cell design. We have found that Li2S deposit has little effect on the impedance response, owing to its porous structure. The most noticeable change stemming from the process of Li2S deposition is due to the depletion of polysulfide species concentration in the electrolyte, which decreases the chemical capacitance and increases the tail height in the low frequency region of the impedance spectra.

Study of the tectonic structure and modern geodynamics of the nickel-copper-sulfide Kun-Manyo deposit at the stage of its field the development

Currently, the Kun-Manyo nickel-copper-sulfide deposit in the north of the Khabarovsk Krai is being prepared for development, with part of the reserves expected to be mined by underground mining. To justify the rational order of opening and excavation of sub-ore reserves it is necessary to have objective information on rock mass condition, which can be received as a result of complex geodynamic and geomechanical investigations. The established geodynamic position of the deposit, determined by its location at the junction of actively interacting large tectonic elements of the Euro-Asian tectonic plate – the tectonic stress of the North Asian craton and the Amur plate, as well as within the modern Olekmo-Stanovo seismic zone, has allowed the massif of the field area to be classified as tectonically stressed. An analysis of the data of the GPS-observation points on the territory of the Russian part of the Amur tectonic plate, the results of calculations of the vector field of velocities of modern movements of points, made within the framework of the ITRF – 2000 coordinate system, as well as the results of in-situ geomechanical studies of rock massifs of the Amur Plate’s rock-bump hazardous deposits, have made it possible to establish the current tectonic regime of the deposit area – a region of intense modern compression with a predicted intensity of more than 50 MPa. By methods of morphometric analysis and remote sensing, it has been found that the relative relief excesses were significant (700–1000 m), which may lead to an uncompensated horizontal component of geostatic stress. The most extended lineaments of the relief have predominantly southeasterly extension. The identified features of the tectonic structure and regional neotectonics have made it possible to determine the most probable direction and magnitude of the current main horizontal compression, which could be further used in solving various geomechanical problems in the exploitation of the field.

Multi-stage sulfide evolution of the Moran Ni sulfide ore, Kambalda, Western Australia: insights into the dynamics of ore forming processes of komatiite-hosted deposits

The Moran komatiite-hosted Ni sulfide deposit at Kambalda (Australia) is one of the better preserved orebodies at Kambalda. Its geochemical signature is used to investigate the evolution of the sulfide mineralization. The orebody has several parts, including a flanking segment where massive sulfides formed relatively early and a central portion in a 40-m-deep erosional embayment representing a later generation of massive and net-textured sulfides. Basal massive sulfides within the deep embayment vary systematically in their chalcophile element contents (Ni, PGE, Au, Te, As, Bi). Elements compatible in monosulfide solid solution (MSS) exhibit the highest concentration at the edge of the orebody (up to 4.3 ppm Ir + Os + Ru + Rh), whereas incompatible elements are most concentrated in the centre (up to 11.2 ppm Pt + Pd + Au). This difference in element distributions is explained by fractional crystallization of sulfide melt from the edge towards the centre. To explain the vertical movement of the residual fractionated melt, a new model of sulfide crystallization is proposed. A low-viscosity boundary layer containing incompatible elements is formed between MSS and sulfide melt. This melt propagates with the crystallization front towards the centre of the sulfide melt pool. Trace element variations in pentlandite (e.g. Co) and composite Co- and Bi-bearing arsenide-telluride grains suggest that during the final stages of crystallization, an immiscible Co-As-Te-Bi melt is formed.

An intermittent detachment faulting system with a large sulfide deposit revealed by multi-scale magnetic surveys

Magmatic and tectonic processes can contribute to discontinuous crustal accretion and play an important role in hydrothermal circulation at ultraslow-spreading ridges, however, it is difficult to accurately describe the processes without an age framework to constrain crustal evolution. Here we report on a multi-scale magnetic survey that provides constraints on the fine-scale evolution of a detachment faulting system that hosts hydrothermal activity at 49.7°E on the Southwest Indian Ridge. Reconstruction of the multi-stage detachment faulting history shows a previous episode of detachment faulting took place 0.76~1.48 My BP, while the present fault has been active for the past ~0.33 My and is just in the prime of life. This fault sustains hydrothermal circulation that has the potential for developing a large sulfide deposit. High resolution multiscale magnetics allows us to constrain the relative balance between periods of detachment faulting and magmatism to better describe accretionary processes on an ultraslow spreading ridge.

Nova-Bollinger Ni-Cu Sulfide Ore Deposits, Fraser Zone, Western Australia: Petrogenesis of the Host Intrusions

The Nova-Bollinger Ni-Cu sulfide ore deposit is the first economic Ni-Cu-Co sulfide deposit to have been discovered in the Albany-Fraser orogen in Western Australia. The host rocks are mafic-ultramafic intrusive cumulates subdivided into two connected intrusions, designated Upper and Lower. The Upper Intrusion is bowl-shaped and modally layered with alternating peridotite and norite mesocumulate layers, with a Basal Series of dominantly orthocumulate mafic lithologies. The Lower Intrusion is a much thinner, semiconformable chonolith (flattened tube-shaped intrusion) consisting of mostly unlayered mafic to ultramafic orthocumulates. The Lower Intrusion hosts all the high-grade mineralization and most of the disseminated ores. A distinctive plagioclase-bearing lherzolite containing both orthopyroxene and olivine as cumulus phases is a characteristic of the Lower Intrusion and the Basal Series of the Upper. The intrusions differ slightly in olivine and spinel chemistry, the differences being largely attributable to the more orthocumulate character of the Lower Intrusion. Sector zoning in Cr content of pyroxenes is observed in the Lower Intrusion and in the lower marginal zone of the Upper and is attributed to crystallization under supercooled conditions. Symplectite pyroxene-spinel-amphibole coronas at olivine-plagioclase contacts are ubiquitous and are attributed to near-solidus peritectic reaction between olivine, plagioclase, and liquid during and after high-pressure emplacement, consistent with high Al contents in igneous pyroxenes and estimates of the peak regional metamorphism. Original cumulus olivines had compositions around Fo86 and were variably Ni depleted, interpreted as the result of preintrusion equilibration with sulfide liquid. The Upper and Lower Intrusion rocks represent cumulates from a similar parental magma, a high-Al tholeiite with MgO between 10 and 12%, low TiO2 (0.5–0.6%), and high Al2O3 (14–17%). Modeling using alphaMELTS indicates a primary water content of around 2 wt %. The cumulates of both intrusions were derived via multiple magma pulses of liquid-olivine-sulfide slurries with variable amounts of orthopyroxene, emplaced into the deep crust at pressures of around 0.7 GPa during the peak of regional metamorphism. The intrusions developed initially as a bifurcating sill, the lower arm developing into the ore-bearing Lower Intrusion chonolith and the upper arm inflating into the cyclically layered Upper Intrusion.