Carbonate Host Research Articles

Waste to Wealth: One-Step Exfoliating of Spent Graphite to Build a Low-Cost Cathode for Lithium-Sulfur Batteries.

With the booming development of Li-ion batteries (LIBs), the recycling and reusing of spent graphite (SG) from LIBs is becoming increasingly crucial. Meanwhile, developing low-cost and efficient carbon hosts for lithium-sulfur (Li-S) batteries has gained widespread attention in the past decade. Nevertheless, the processing of carbon materials as sulfur hosts is often energy-consuming and complex. Herein, a simple and environmental-friendly strategy is proposed to reuse the SG to prepare graphene/sulfur composite cathode for Li-S batteries. Due to expanded layer spacing and defects of SG, sulfur molecules can strip it into a graphene-type host via ball milling. By optimizing the S/SG ratio and ball milling time, the as-prepared graphene/sulfur composite cathode with 70 wt.% sulfur content exhibits a high capacity of 1000 mAh g-1. With a high sulfur loading of 4.68 mg cm-2, the graphene/sulfur cathode can maintain 526 mAh g-1 after 400 cycles. This work provides a novel waste-to-wealth perspective for recycling spent graphite from LIBs to reuse in Li-S batteries.

Enhanced carbon host with N-reinforced S-sites to catalyze rapid iodine conversion kinetics for Zn-I2 battery

Aqueous zinc-iodine (Zn-I2) battery is a promising energy storage system in the establishment of a low-carbon, clean society, but they are limited by unsatisfied reversible capacity and poor cycle life. Ultimately, this is due to the poor iodine conversion kinetics and the shuttle effect of the intermediate polyiodide. Herein, a N-reinforced S-site carbon host (labeled as NS-YP80F) is designed to resolve these issues. DFT calculation shows that the electrochemical activity of the NS-YP80F with abundant S-site can be further enhanced by introducing N-atom at the original S-site. The synergistic effect of N-reinforced S-site carbon host cannot only enhance the adsorption of polyiodide to avoid the shuttle effect, but also induce the smooth conversion of iodine through enhanced catalytic mechanism. Consequently, the Zn-I2 battery with NS-YP80F@I2 cathode shows high reversible capacity (127 mAh g−1 at 1C) and stable cycling lifespan (15,000 cycles) with a high current density of 50 C. This strategy achieved a breakthrough in the electrochemical activity of the heteroatom doping carbon hosts, and provided a simple and effective solution for optimizing the performance of Zn-I2 battery.

Realizing interfacial coupled electron/ion transport through reducing the interfacial oxygen density of carbon skeletons for high-performance lithium metal anodes

Lithium plating/stripping occurs at the anode/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase (SEI). The dual continuous rapid transport of interfacial electron/ion is required for homogeneous Li deposition. Herein, we propose a strategy to improve the Li metal anode performance by rationally regulating the interfacial electron density and Li ion transport through the SEI film. This key technique involves decreasing the interfacial oxygen density of biomass-derived carbon host by regulating the arrangement of the celluloses precursor fibrils. The higher specific surface area and lower interfacial oxygen density decrease the local current density and ensure the formation of thin and even SEI film, which stabilized Li+ transfer through the Li/electrolyte interface. Moreover, the improved graphitization and the interconnected conducting network enhance the surface electronegativity of carbon and enable uninterruptible electron conduction. The result is continuous and rapid coupled interfacial electron/ion transport at the anode/electrolyte reaction interface, which facilitates uniform Li deposition and improves Li anode performance. The Li/C anode shows a high initial Coulombic efficiency of 98% and a long-term lifespan of over 150 cycles at a practical low N/P (negative-to-positive) ratio of 1.44 in full cells.

Basin inversion, drifting and hyper-extension in the Central Atlantic Ocean and Maghrebian Tethys as fluid driving mechanisms for the superimposed base metal mineralization events in the Jbel Bou Dahar carbonate-hosted Pb-Zn-Ba deposits (High Atlas, Morocco)

The Early Jurassic Jbel Bou Dahar reef-bearing carbonate platform in the eastern High Atlas, Morocco, contains numerous carbonate-hosted and fault-controlled Pb-Zn-Ba deposits, prospects, and showings. Combined field, petrographic and geochemical data, including REE + Y analyses, stable (C-O-S), radiogenic (SrPb) and noble gas (He, Ne, Ar) isotopic compositions, record two temporally distinct metallogenic events. Both events are related to post-rifting and inversion of the inherited Mesozoic Atlas paleorift. The ore deposits are thought to have been formed during large-scale episodes of transtensional basin evolution, which developed as a far-field effect of the drifting of the Central Atlantic Ocean and Maghrebian Tethys while the basin continued to invert in response to the ongoing convergence between the African and the Eurasian plates. The paragenetically earliest Zn-rich ore was generated in a transtensional setting coincident with the hyper-extension of Maghrebian Tethys and the initial stages of drifting and formation of the Central Atlantic passive margin. Crustal extension and high heat fluxes provided by the hot upwelling mantle would have triggered buoyancy-driven convection of deeply sourced fluids and maturation of organic matter dispersed within the host carbonates to produce hydrocarbons within an extensional basin setting. These relatively reduced Zn-rich ore-forming fluids acquired metals mainly through protracted interaction with the country rocks including the underlying Triassic siliciclastic series and the granitic basement rocks. Regional ENE- to E-W-trending major faults would have acted as conduits for upward fluid flow and traps for Zn-Pb-Ba mineralization. Conversely, the late Pb-rich mineralization stage II is broadly constrained to have occurred between ca. 70 Ma and 10 Ma and is thought to be related to the transition from orogenic shortening (late Eocene) to post-orogenic crustal extension and exhumation (early Miocene) following Alpine orogenic collapse. Mixing of down-ward percolating meteoric fluids and ascending rock-buffered hydrothermal brines that had previously equilibrated with the radiogenic basement rocks along with thermochemical sulfate reduction of transported sulfate and/or thermal cracking, would have been the main ore-forming processes that controlled ore deposition. Given these fluid characteristics and geodynamic settings, the Jbel Bou Dahar ore field is classified as a hybrid carbonate-hosted Pb-Zn-Ba district formed by the juxtaposition of two deposit types rather than one progressively evolving mineralizing system. From an exploration standpoint, new delineation here of the two metallogenic events provides valuable exploration tools for further targeting PbZn and barite resources in the Atlas system of North Africa and other areas where similar orogenic belts experienced post-rift subsidence and basin inversion.

The effect of carbonate assimilation and nanoheterogeneities on the viscosity of phonotephritic melt from Vesuvius

Interaction between magma and carbonate plays a pivotal role in volcanic systems, yet its impact on magma transport properties remains inadequately explored. This study presents novel viscosity data on a leucite-bearing phonotephritic melt from the 472 CE Pollena eruption (Vesuvius, Italy), doped with varying amounts of CaO and CaO + MgO. The compositions match the chemistry of melt inclusions and interstitial glasses from skarns at Vesuvius, which have been interpreted as related to mixing of magma with different amounts of CaO and MgO derived from the host carbonates (limestone and dolostone). Viscosity measurements were conducted at both high (1150–1400 °C) and low temperatures (640–760 °C) by concentric cylinder viscometry, differential scanning calorimetry, and micropenetration methods. Through an integrated approach which combines Brillouin and Raman spectroscopy with the aforementioned techniques, we accurately predict the viscosity changes induced by magma‑carbonate interaction and identify the formation of nanoheterogeneities during low-temperature viscosity measurements. Notably, viscosity models from the literature fail to accurately reproduce our experimental data set at both high and low temperature. In the high-temperature regime, the addition of CaO induces a remarkable viscosity decrease, surpassing that produced by CaO + MgO addition. Furthermore, our findings reveal a significant viscosity/temperature crossover resulting from the addition of CaO and CaO + MgO to the melt phase. Undoped melt exhibits a higher viscosity compared to doped melts above 750 °C, with an inverse trend observed below this temperature threshold. Such rheological constraints may affect the mobility and mixing capability of melts exposed to different levels of carbonate assimilation.

Structural Engineering of Carbon Host Derived from Organic Pigment toward Physicochemically Confinement and Efficient Conversion of Polysulfide for Lithium–Sulfur Batteries (Small Methods 9/2024)

Structural Engineering of Carbon Host Derived from Organic Pigment toward Physicochemically Confinement and Efficient Conversion of Polysulfide for Lithium–Sulfur Batteries (Small Methods 9/2024)

Curvature-induced strain to realize differential lithiophilicity for selective lithium deposition and stable lithium anode

Regulating the lithiophilicity of three-dimensional (3D) lithium hosts is crucial for improving lithium deposition and suppressing dendrite growth. However, previous research has mainly focused on varying lithiophilic components, and the impact of geometric structures induced strain remains poorly understood. Herein, we present a novel curvature-induced strain engineering approach to regulate lithiophilicity and deposition kinetics of lithium in lightweight 3D tubular carbon hosts. A hollow carbon fiber with bilateral growth of MnO2 nanosheet arrays both inside and outside the tubes (MnO2@HCFC) have been successfully synthesized. Theoretical calculations and experiments confirm that the MnO2 layers inside and outside the hollow carbon fiber tube undergo compressive and tensile strain, respectively. The curvatures induced strain modifies the O2p band center of the lithiophilic MnO2 layer, enabling the regulation of lithiophilicity and preferential and uniform lithium deposition within the carbon fiber tubes. The MnO2@HCFC framework exhibits excellent lithium affinity and uniform Li+ flux distribution, as evidenced by visualization techniques and COMSOL simulations, enabling dendrite-free lithium deposition. The Li-MnO2@HCFC||LiCoO2 full cell retains 85.7 % of its capacity after 400 cycles at 0.5 C with a high LiCoO2 loading of 10.3 mg cm-2. The optimized lithium anode pouch cell exhibits robust cycle stability under harsh conditions. This work offers new insight into the design of 3D lithium hosts to enhance the performance of lithium anodes through curvature-induced strain engineering.

Mesoporous Carbons Produced from Tannin Biomass for Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) are promising alternatives since sulfur can provide a theoretical specific capacity of 1675 mA h g-1 when combined with lithium [1]. Thus, LSBs can achieve a theoretical energy density (2500 W h kg-1) that is much greater than that of conventional lithium-ion batteries [1]. However, several problems must be resolved to enable commercial production on a large scale, such as the formation of soluble species of lithium polysulfides [2]. Various approaches have been used to minimize this problem, including the development of carbon-based hosts capable of retaining these polysulfides. Among these, the development of cathodes based on carbon‒sulfur composites using carbon from biomass is an alternative that benefits from the possibility of obtaining materials with a modifiable surface area and porosity at low cost [2]. On this basis, this work reports the synthesis of mesoporous carbons (MCs) from tannin biomass, the incorporation of sulfur and the development of lithium-sulfur batteries. The MC sample was produced using the solvent-free method [3] and was named C. The incorporation of sulfur into mesoporous carbons was carried out using melt diffusion methodology [4]. Two quantities of sulfur were added to the carbon host by mass, and the materials were named CS1 and CS2 at ratios of 1:1 and 2:1, respectively, in relation to sulfur:MC. Coin cells (CR 2032) were assembled using the produced materials on the cathode, metallic Li on the anode and the electrolyte 1 M LiTFSI and 1% (w/v) LiNO3 in 1,2-dimethoxyethane/1,3-dioxolane (DME/DOL) and characterized by cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) cycling. The mesoporous carbon C presented a type IV isotherm characteristic of mesoporous materials, with a BET surface area of 539 m2g-1, average pore size of 7.7 nm and total pore volume of 0.747 cm3g-1. There was a decrease in the area and pore volume of the materials after sulfur incorporation, reaching 70 m2g-1 and 0.195 cm3g-1 for CS1 and 3 m2g-1 and 0.012 cm3g-1 for CS2, respectively. The sulfur contents were determined by thermogravimetric analysis (TGA) and were 39% and 61% for CS1 and CS2, respectively. The sulfur contents determined by TGA were close to those obtained by elemental analysis (CHNS), which were 45% and 63% for CS1 and CS2, respectively. The CV data showed that both cells presented cathodic and anodic potentials typical of Li-S batteries. The GCD data show that the cell containing the cathode with the material with a higher elemental sulfur content (CS 2) is stable and maintains specific capacities on the order of 550 mA h g-1 after 45 galvanostatic cycles at different current densities. However, this cell showed a more abrupt decrease in capacity at the highest rates (2C and 4C), Figure 1. Most likely, the higher sulfur content used in this sample did not result in total impregnation of the porous structure, resulting in sulfur deposition on the surface of the particles. As a result, the interparticle contact resistance in the electrodes increases, which limits the performance at higher current demands. For the cell built with the sample containing 39% S (CS1), excellent performance is obtained at high C rates. At 0.1 C, the cathode operates above 900 mA h g-1 in the initial cycles and above 550 mA h g-1 at 0.5 C, and no significant capacity drop is observed between 1 C and 2 C (≈500 mA h g-1). At 4C, a decrease in the specific capacity is noted, but the specific capacity remains above 350 mA h g-1. These results demonstrate the potential of carbon materials obtained from biomass for building high-performance Li-S batteries.Acknowledgments: The authors thank the financial support from the Rota 2030 Program at Fundep – Brazil.

Confining Iodine into Metal-Organic Framework Derived Metal-Nitrogen-Carbon for Long-Life Aqueous Zinc-Iodine Batteries.

Aqueous zinc-iodine batteries (AZIBs) are highly appealing for energy requirements owing to their safety, cost-effectiveness, and scalability. However, the inadequate redox kinetics and severe shuttling effect of polyiodide ions impede their commercial viability. Herein, several Zn-MOF-derived porous carbon materials are designed, and the further preparation of iron-doped porous carbon (Fe-N-C, M9) with varied Fe doping contents is optimized based on a facile self-assembly/carbonization approach. M9, with atomic Fe coordinated to nitrogen atoms, is employed as an efficient cathode host for AZIBs. Functional modifications of porous carbon hosts involving the doping species and levels are investigated. The adsorption tests, in situ Raman spectroscopy, and in situ UV-vis results demonstrate the adsorption capability and charge-discharge mechanism for the iodine species. Furthermore, experimental findings and theoretical analyses have proven that the redox conversion of iodine is enhanced through a physicochemical confinement effect. This study offers basic principles for the strategic design of single-atom dispersed carbon as an iodine host for high-performance AZIBs. Flexible soft-pack battery and wearable microbattery applications also have implications for future long-life aqueous battery designs.

Unveiling the In Situ Evolution of Li2O-Rich Solid Electrolyte Interface on CoOx Embedded Carbon Fibers as Li Anode Host.

Modification of three-dimensional (3D) carbon hosts with metal oxides has been considered as advantageous for the formation of Li2O-rich solid electrolyte interface (SEI), which can show fast Li+ diffusion, and meanwhile alleviate dendrite problems caused by fragility and nonuniformity of native SEIs. However, the lack of convincing experimental evidence has made it difficult to unveil the true origin of oxygen in Li2O-rich SEIs until now. Herein, CoOx embedded carbon nanofibers (CNF-CoOx) are successfully prepared as high-performance Li anode hosts. By employing 18O isotope labeling, the role of CoOx during SEI evolution is elucidated, revealing that CoOx contributes significantly to Li2O formation by delivering oxygen. Benefiting from the rich Li2O content, the as-formed SEIs greatly improve the Li+ migration kinetics, and therefore, the CNF-CoOx@Li anode can exhibit excellent cycling stability in half, symmetrical, and full cells.

Determining the age and origin of a Tertiary karstic system by in situ U-Pb geochronology on speleothems

Abstract Dating the onset of ancient (>1 Ma) karstification is a challenge. One approach is to date the earliest calcite cements in speleothems. We show the benefits of in situ U-Pb dating directly on thin sections from ancient (ca. 30 Ma) thin (<1 mm) speleothems in the karstified Lower Oligocene lacustrine-palustrine carbonates of the Paris Basin (France), which cannot be dated using other methods. We dated 32 calcite rafts (a type of speleothem), one geopetal cement, and 10 calcite cements precipitated along the karstic walls. The ages of the calcite rafts and cements at 29 ± 1 Ma (Lower Oligocene) fall within the age range of the host deposits (≈29 Ma) previously deduced from palaeontological evidence. We demonstrate that cementation of the carbonate host rock, its dissolution, and the speleothem precipitation occurred within 2 m.y. after deposition. Ostracods and intraclasts trapped within Rupelian calcite rafts clearly indicate that the karst developed deep underground shortly before a phase of lacustrine-palustrine sedimentation at the surface. This very early dissolution episode is attributed to the uplift of the Paris Basin as a result of the far-field intraplate deformation induced by the alpine orogenesis. This study shows that in situ U-Pb geochronology on ancient calcite rafts is a promising technique for the indirect dating of karstification and, more broadly, for dating geodynamic events and diagenetic evolution of sedimentary basins.

In‐Situ Laser Synthesis of Molecularly Dispersed and Covalently Bound Phosphorus‐Graphene Adducts as Self‐Standing 3D Anodes for High‐Performance Fast‐Charging Lithium‐Ion Batteries

AbstractPhosphorus shows promise as a next‐generation anode material due to its high theoretical capacity of 2596 mAh g−1. However, challenges such as low conductivity, severe volume expansion, and the dissolution and migration of electrolyte‐soluble lithium polyphosphides hamper high‐performance capabilities. While carbon composites are widely researched as a solution through the physical encapsulation of micro‐nano‐phosphorus domains, anodes still exhibit low cycling stability and rate performance. In response, this work proposes a new approach, focusing on chemical anchoring and molecular dispersion of phosphorus within the carbon host. Through laser irradiation of a red phosphorus/phenolic resin blend, in‐situ covalent binding of molecular phosphorus adducts to the as‐forming laser‐induced graphene is observed; directly synthesizing an additive‐free, flexible and 3‐dimensional mesoporous composite anode with high phosphorus content (33 wt.%), specific surface area (163.4 m2 g−1) and intrinsic conductivity (12 S cm−1). These anodes demonstrate remarkable cycling stability, with capacity retention of 98% after 3000 cycles at a high current density of 2 A g−1 and capacity of 673 mAh g−1. The high cycling stability is further confirmed through the complete inhibition of lithium polyphosphide “shuttle effect” by chemical anchoring of the molecularly dispersed active material. Furthermore, scale‐up prospects utilizing laser‐assisted additive manufacturing are investigated.

Ultrathin Two-Dimensional Ordered Porous Carbon Host with Atomically Dispersed Electrocatalytic Sites toward High Volumetric Energy Lithium-Sulfur Battery

Despite multimodal approaches to increase the gravimetric capacity of lithium-sulfur (Li-S) batteries over the years, strategies on achieving high volumetric capacity (Qv) at close to practical cell operating conditions with high areal sulfur loading and low electrolyte-to-sulfur (E/S) ratio are still lacking. Here, we report that a synergistic effect of a carbonaceous framework with precisely-controlled porous structure/dimension and highly-active, surface-mediated electrocatalysis by a ruthenium (Ru) single-atom electrocatalyst (SAC) composed of N2RuCl2 achieves high Qv in Li-S batteries. Two-dimensional (2D) and hierarchically ordered porous structures of polymer interfacial self-assembly derived N-doped carbon nanosheets (NCNS) realize a highly-packed sulfur cathode with outstanding Li+ ion diffusivity and electrode stability, which have been considered as main impediments to achieving high Qv in a dense sulfur cathode. Moreover, homogeneous incorporation of N2RuCl2 SAC which has novel Ru coordination environment with two N and Cl atoms on the surface of NCNS remarkably accelerated the reaction kinetics of Li-S electrochemistry and achieved high Qv even at high sulfur loading (5.0 mg cm−2), extremely low E/S ratio (4.5 μL mg−1), and low electrode porosity (50 %).

Iron, cobalt co-embedded in situ graphitized xerogel-derived carbon as sulfur host for ultrahigh rate and high-performance lithium-sulfur batteries

Lithium‑sulfur battery (LSB) is an enticing technology because of its high specific capacity, potential energy density, and natural abundance of sulfur in the earth's crust. However, some notorious issues need to mitigate before commercialization. Here we report a novel and scalable iron, cobalt co-embedded resorcinol formaldehyde derived carbon framework as sulfur host for high-performance LSB. To further increase the specific surface area and porosity of carbon, polyvinyl alcohol (PVA) is used as a sacrificial polymer. One pot synthesis method is used for preparing the Fe, Co co-embedded PVA incorporated RF xerogel-derived carbon (FC-PRFC) framework. The first-principles calculations suggest the advantage of bimetallic doping in enhancing the binding energy and reducing the energy gap of the carbon host for polysulfide anchoring. The porous structure and higher specific area of FC-PRFC enable high sulfur loading in the composite and show excellent rate performance and cyclability, as suggested by detailed electrochemical analysis. Moreover, the FC-PRFC cathode host with a high areal sulfur loading of 4.2 mg cm−2 delivers a high initial discharge capacity of 1283 mAh g−1 at 0.1C. During long-cycling at a high current rate of 4C, it retains a capacity of 372 mAh g−1 after 400 charge-discharge cycles with a capacity retention of 73 %. This scalable, innovative, low-cost fabrication technique has the potential to pave the way for developing an outstanding xerogel-derived carbon framework for high-performance LSBs for commercial applications.

An Investigation into Electrolytes and Cathodes for Room-Temperature Sodium–Sulfur Batteries

In the pursuit of high energy density batteries beyond lithium, room-temperature (RT) sodium–sulfur (Na-S) batteries are studied, combining sulfur, as a high energy density active cathode material and a sodium anode considered to offer high energy density and very good standard potential. Different liquid electrolyte systems, including three different salts and two different solvents, are investigated in RT Na-S battery cells, on the basis of the solubility of sulfur and sulfides, specific capacity, and cyclability of the cells at different C-rates. Two alternative cathode host materials are explored: A bimodal pore size distribution activated carbon host AC MSC30 and a highly conductive carbon host of hollow particles with porous particle walls. An Na-S cell with a cathode coating with 44 wt% sulfur in the AC MSC30 host and the electrolyte 1M NaFSI in DOL/DME exhibited a specific capacity of 435 mAh/gS but poor cyclability. An Na-S cell with a cathode coating with 44 wt% sulfur in the host of hollow porous particles and the electrolyte 1M NaTFSI in TEGDME exhibited a specific capacity of 688 mAh/gS.

Confinement of iodine species into oxygen doped hierarchical porous carbon host for high loading zinc-iodine batteries

The aqueous zinc-iodine batteries (ZIBs) have been expected to be the most promising next-generation energy storage device. However, it is still struggling with the limited intrinsic electronic conductivity, poor thermal stability and high solubility of the discharge products. Additionally, the iodine loading is below 2 mg cm−2 in most of the reported aqueous ZIBs, impeding their widespread application. Herein, we present a one-step production method for O-doped hierarchical porous carbon framework (OHPCF) from biomass as an iodine host material to solve the problems mentioned above. Benefiting from synergistic physical confinement (high-density microporous structure) and chemical anchoring (abundant oxygen atom doping) effect of the OHPCF samples, the electrode exhibits low polarization, high iodine utilization and excellent electrochemical stability in ZIBs. Encouragingly, we achieve an ultra-high area capacity of 3.3 mAh cm−2 with a loading of 20.3 mg cm−2, demonstrating its superior application potential. This work introduces a simple yet effective strategy for developing 3D microporous electrodes for ZIBs with high iodine loading, enabling high areal capacity with remarkable rate and cycling performance.

Enhancement of Li/S Battery Performance by a Modified Reduced Graphene Oxide Carbon Host Decorated with MoO3.

Electrochemical energy storage systems based on sulfur and lithium can theoretically deliver high energy with the further benefit of low cost. However, the working mechanism of this device involves the dissolution of sulfur to high-molecular weight lithium polysulfides (LiPs with general formula Li2Sn, n≥4) in the electrolyte during the discharge process. Therefore, the resulting migration of partially dissociated LiPs by diffusion or under the effect of the electric field to the lithium anode, activates an internal shuttle mechanism, reduces the active material and in general leads to loss of performance and cycling stability. These drawbacks poses challenges to the commercialization of Li/S cells in the short term. In this study, we report on the decoration of reduced graphene oxide with MoO3 particles to enhance interactions with LiPs and retain sulfur at the cathode side. The combination of experiments and density functional theory calculations demonstrated improvements in binding interactions between the cathode and sulfur species, enhancing the cycling stability of the Li/S cells.

Facile one-pot synthesis of Co3Mo3N-loaded inside hierarchical porous bead-on-string as cathode host material for high-performance lithium-sulfur batteries

A critical factor impeding the development of lithium-sulfur batteries is the deleterious shuttle effect. To address the issue, we devise a facile electrospinning approach to integrate catalysts and hierarchically porous structures into bead-on-string carbon host material as the host material. Compared to the traditional preparation of hierarchical porous structures, the upgraded electrospinning eliminates the need for etching templates, providing a larger specific surface area (333.39 m2 g−1) and tremendous potential for large-scale production. The cathode utilizing bead-on-string Co3Mo3N as host material exhibits a remarkable capacity of 1257 mAh g−1 at 0.2 C and maintains a capacity retention rate of 90 % after 100 cycles. Even at 4.0 C, the capacity remains at 648 mAh g−1 with minimal capacity loss. Under harsh conditions (including high sulfur loading, high areal loading, and lean electrolyte), the composite cathode consistently delivers a capacity of 8 mAh cm−2. Simultaneously, systematic electrochemical testing, in-situ assessments, and DFT calculations unveil the dual-metal synergistic effects of Co3Mo3N in suppressing the shuttle effect and catalyzing the conversion of lithium polysulfides. Co3Mo3N provides chemical adsorption to significantly promote the reaction kinetics of polysulfides. This work establishes a neoteric technique and a theoretical strategy for exploring the catalytic efficacy of dual-metal nitrides for Li-S batteries.

On-surface conversion reaction realizes advanced red phosphorus/carbon anode for high-performance lithium-ion batteries

Red phosphorus (RP), the one of the most prospective anodes in lithium-ion batteries (LIBs), has been severely limited due to the intrinsic defects of massive volume expansion and low electronic conductivity. The vaporization-condensation-conversion (VCC), which confines RP nanoparticles into carbon host, is the most widely used method to address the above drawbacks and prepare RP/C nanostructured composites. However, the volume effect-dominated RP caused by the inevitably deposition of RP vapor on the surface of carbon material suffers from the massive volume change and unstable solid electrolyte interface (SEI) film. Herein, we propose a simple interfacial modification method to eliminate the superficial RP and yield stable surface composed of ion-conducting Li3PS4 solid electrolyte, endowing RP/AC composites excellent cycling performance and ultrafast reaction kinetics. Therefore, the RP/AC@S composites exhibit 926 mAh/g after 320 cycles at 0.2 A/g (running over 181 days), with 81.6 % capacity retention and a corresponding capacity decay rate of as low as 0.059 %. When coupled with LiFePO4 cathode, the full cells present superior cycling performance (62.1 mAh/g after 500 cycles at 1 A/g) and excellent rate capability (81.1 mAh/g at 1.0 A/g).

Magmatic and hydrothermal evolution of the superlarge Dashui goldfield in the West Qinling Orogen, China

Gold (Au) is a precious metal that has played an important role in the development of the global economy. It is therefore important to better define the genesis of Au mineralisation as an aid to focus exploration as the consumption of Au increases. The Dashui goldfield contains a super large Au resource of over 120 t (tonnes) in the West Qinling Orogen, central China. Despite several studies have focused on the genesis of the Dashui goldfield, the original physico–chemical natures of magmatic and hydrothermal evolution remain unclear. Biotite and apatite in the mineralised diorite porphyry of the goldfield are sensitive to the changes in the physico–chemical conditions and the evolution of magmatic and hydrothermal fluids, and thus provide important keys to address these issues. Hence, we conducted detailed in–situ major and trace element studies of biotite and apatite from the ore–bearing diorite porphyry in the Dashui goldfield. Our aim is to elucidate the physico–chemical conditions, magma source, and magmatic and hydrothermal evolution processes during the deposition of the gold, and to enhance the understanding of the Au genesis in the West Qinling Au province. Using the geochemistry of magmatic apatite, and magmatic and hydrothermal biotite, we have found that the crystallisation temperature and pressure along with emplacement depth of diorite porphyry were constrained at ∼ 737–791 °C, 1.08–1.73 kbar, and 3.94–6.30 km. The diorite porphyry has the geochemical affinities with calcium alkaline orogenic suites derived from a mixed crustal and mantle source. During the early emplacement of diorite porphyry, the melt had a high oxygen fugacity and was highly enriched in Au. During the late magma crystallisation of diorite porphyry, the magma was enriched continuously in most elements with the Ba/Rb ratios in the biotite varying from 10 to 5, and most of the Au was hosted by pyrite. Additionally, elements were continuously dissolved into fluids generating Cl–rich hydrothermal fluids during the evolution of the magma. During hydrothermal evolution, Au is migrated with As and Sb in the vapour phases of fluids, whereas Au migrated with Cl in the liquid phase. When temperatures dropped to ∼ 200–400 °C, Au started to combine with S and Si in the liquid phase of fluids. Subsequently, hydrothermal fluids interacted with host carbonate to form the Dashui goldfield, Au during this stage was also transported and hosted in magnetite, hematite, and quartz within the carbonate rocks.