Polar Ion Research Articles

A Catalytic Disproportionation Reaction of Polysulfides Enabled By a Bio-Carbon Host for Li-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are regarded one of the promising alternatives of conventional lithium-ion (Li-ion) batteries because of its high theoretical energy density (2600 Wh kg-1), abundance resources on earth, and low cost of sulfur. Nevertheless, several significant challenges persist in the practical application of Li-S batteries, with the most urgent being the dissolved shuttle effect of long-chain lithium polysulfide (LiPS) species during cycling [1]. Using porous host material for sulfur cathode is one of the commonly applied strategies to physically prevent the diffusion of LiPS from diffusing toward lithium anode, and therefore inhibit the shuttle effect [2]. However, the weak Van der Waals forces is in sufficient to anchor the dissolved LiPS because the non-polar surface of carbon material is unable to bind polar and ionic polysulfide ions. Introducing heteroatoms into the host materials is a way to enhancing anchoring of PS at cathode side [3]. In our previous research, we reported a novel carbon host (denoted as NC) for sulfur cathode from natural silk [4]. The obtained carbon host presented excellent cycling performance because of its hierarchical porous structures and nitrogen-contained functional group. In addition, we found the carbon has the ability to catalyst the disproportionation reactions of PS, accelerating the conversion of PS ions into solid products of elemental sulfur (S8) and lithium sulfide (Li2S2) serves to minimize the residence time of PS ions in the electrolyte. In this study, we proposed a hypothesis of a catalytic pseudo-8-electron redox reaction of S/NC cathode and analysis the process using high-performance liquid chromatograph (HPLC) analysis and electrochemical characterizations.[1] Zhang, S. S. (2013). Liquid electrolyte lithium/sulfur battery: Fundamental chemistry, problems, and solutions. Journal of Power Sources, 231, 153-162.[2] Ye, H., Yin, Y. X., Xin, S., & Guo, Y. G. (2013). Tuning the porous structure of carbon hosts for loading sulfur toward long lifespan cathode materials for Li–S batteries. Journal of Materials Chemistry A, 1(22), 6602-6608.[3] Song, J., Xu, T., Gordin, M. L., Zhu, P., Lv, D., Jiang, Y. B., ... & Wang, D. (2014). Nitrogen‐doped mesoporous carbon promoted chemical adsorption of sulfur and fabrication of high‐areal‐capacity sulfur cathode with exceptional cycling stability for lithium‐sulfur batteries. Advanced functional materials, 24(9), 1243-1250.[4] Qiu, D., Zhang, X., Zheng, D., Ji, W., Ding, T., Qu, H., ... & Qu, D. (2023). High-performance Li-S batteries with a minimum shuttle effect: disproportionation of dissolved polysulfide to elemental sulfur catalyzed by a bifunctional carbon host. ACS Applied Materials & Interfaces, 15(30), 36250-36261

The utility of MOF-based materials in direct air capture (DAC) application to ppm-level CO2

Metal-organic frameworks (MOFs) are well-suited materials for CO2 removal and have robust capture capacity and selectivity. Although the adsorption of CO2 in MOFs has been studied, the implementation of ppm-level CO2 uptake in MOFs and the effects of the pore size and charge have not been fully explored. We performed grand canonical Monte Carlo (GCMC) simulations combined with the Density Functional Theory plus U (DFT + U) charge method to investigate MOF screening for ppm-level CO2 uptake and its application in a direct air capture (DAC) system. Three types of MOFs containing eight members were studied: i.e., ZIF-68, 69, 70; UiO-66, 67, 68; CAU-10; and MIL-125. The pore landscape characterization, electrostatic field-induced enhancement, and preferential binding sites of these MOFs were examined for CO2 capture. MOFs with pore limited diameters (PLD) 1.5 times the size of CO2 molecules and with large cavity diameters (LCD) smaller than 10 Å exhibit robust confinement capacity. Polar functional groups and metal ions dominate the electrostatic contributions and subsequently enhance the surface adhesion of CO2 molecules. For a given framework, favorable CO2 binding occurs in the following order: small pores/cages > polar functional group/metal ions > larger pores/cages. ZIF-69 which comprises smaller pores (7.5 Å) and robust polar functional groups (–Cl) collectively enhances CO2 capture; thus, ZIF-69 outperforms other MOFs; the performance of ZIF-69 is followed by that of CAU-10 which has an optimal pore size of 6 Å. These findings are of fundamental and practical importance for the application of MOFs in DAC technologies for CO2 removal.

Paradoxical peeling patterns

Processes ranging from fracture of crystals to peeling of tape have been known for many decades to emit light through a mechanism believed to be associated with electrical charging of separating surfaces. This topic, broadly termed fractoluminescence, has been proposed to be involved in several remarkable phenomena, including medical diagnostics and the generation of X-rays in the lab and earthquake lightning in nature. Here we add the paradoxical finding that two separating surfaces produce entirely different charge patterns, despite originating from the same interface. Further, we report the discovery of a rich variety of new and unexplained patterns, and we examine the hypothesis that the patterns are produced by migration of either polar or non-polar discharge ions onto contact-charged surfaces. This hypothesis may first explain prior findings that charge patterns can extend far beyond points of contact, and second suggests that the ultimate charge imparted on surfaces depends both on well-characterized mechanisms of surface potential and on highly variable discharge ions in the surrounding environment.

Potential Water Collection From Air by Chloride Perovskites.

Directly capturing water from the air has become a compelling strategy to secure water resources. Yet, challenges persist with sorption-based hygroscopic materials, such as inadequate water adsorption efficiency, material degradation post-adsorption, and the need for energy input during water collection. This study introduces an alternative category of sorbent materials potentially for atmospheric water harvesting-metal chloride perovskites-that exhibit spontaneous water vapor adsorption and liquid water collection. This water uptake capability stems from the uncoordinated polar ions that form hydrogen bonds with water molecules, while the cubic lattice imparts a solid framework ensuring structural stability and inhibiting hydrolysis. The methylammonium lead chloride perovskite pellets exhibit efficient water collection performance, with a record absorption rate of 0.841 L m-2 h-1 and a total water collection of 3.675 L m-2 within a 7-h cycle. This initiative attempts to provide a new material class candidate for the potential application of passive atmospheric water harvesting.

Theoretical Study of an Authentic Hydrocarbon Ion Pair.

For many years researchers believed that hydrocarbons only contain covalent bonds. However, since 1985 Okamoto et al. demonstrated the formation of hydrocarbon salts in several systems, demolishing the structural principle that hydrocarbons only contain covalent bonds. Despite the great importance of this outcome to the study of chemical bonds, quantum chemical calculations on these systems are essentially nonexistent. The stability of the hydrocarbon ions along with the steric hindrance associated with the formation of the covalent bond contribute to their occurrence either in solution (dissociated) or in the solid state. These facts along with the common formation of ion pairs in solvents of low polarity motivated us to search for hydrocarbon ion pairs in the gas phase. Its energetics has also been studied in four nonprotic solvents, through a continuum solvation model (CPCM). DFT and CASSCF calculations indicate a metastable and highly polar ion pair between the tricyclopropylcyclopropenylium cation and a simplified Kuhn's anion. The barrier to the covalent structure varies from ∼4.8 to 14.4 kcal/mol, while the energy difference between the ion pair and the covalent form varies from ∼4.3 to 25.4 kcal/mol. The obtained theoretical results along with previous experimental results suggest the following strategy to obtain kinetically and thermodynamically stable hydrocarbon ion pairs: choose very stable hydrocarbon ions and systematically increase the steric hindrance between them.

CNS/PNS proteoglycans functionalize neuronal and astrocyte niche microenvironments optimizing cellular activity by preserving membrane polarization dynamics, ionic microenvironments, ion fluxes, neuronal activation, and network neurotransductive capacity.

Central and peripheral nervous system (CNS/PNS) proteoglycans (PGs) have diverse functional roles, this study examined how these control cellular behavior and tissue function. The CNS/PNS extracellular matrix (ECM) is a dynamic, responsive, highly interactive, space-filling, cell supportive, stabilizing structure maintaining tissue compartments, ionic microenvironments, and microgradients that regulate neuronal activity and maintain the neuron in an optimal ionic microenvironment. The CNS/PNS contains a high glycosaminoglycan content (60% hyaluronan, HA) and a diverse range of stabilizing PGs. Immobilization of HA in brain tissues by HA interactive hyalectan PGs preserves tissue hydration and neuronal activity, a paucity of HA in brain tissues results in a pro-convulsant epileptic phenotype. Diverse CS, KS, and HSPGs stabilize the blood-brain barrier and neurovascular unit, provide smart gel neurotransmitter neuron vesicle storage and delivery, organize the neuromuscular junction basement membrane, and provide motor neuron synaptic plasticity, and photoreceptor and neuron synaptic functions. PG-HA networks maintain ionic fluxes and microgradients and tissue compartments that contribute to membrane polarization dynamics essential to neuronal activation and neurotransduction. Hyalectans form neuroprotective perineuronal nets contributing to synaptic plasticity, memory, and cognitive learning. Sialoglycoprotein associated with cones and rods (SPACRCAN), an HA binding CSPG, stabilizes the inter-photoreceptor ECM. HSPGs pikachurin and eyes shut stabilize the photoreceptor synapse aiding in phototransduction and neurotransduction with retinal bipolar neurons crucial to visual acuity. This is achieved through Laminin G motifs in pikachurin, eyes shut, and neurexins that interact with the dystroglycan-cytoskeleton-ECM-stabilizing synaptic interconnections, neuronal interactive specificity, and co-ordination of regulatory action potentials in neural networks.

Effects of Ti4+ doping on electrochemical properties of LiNi0.815Co0.15Al0.035O2 cathode materials

The high nickel ternary cathode materials LiNi0.815Co0.15Al0.035O2 (NCA) have been widely used in Li-ion batteries due to their high energy density, low cost, and little environmental pollution. However, it suffers from rapid capacity degradation and poor charging rate. In this work, Ti4+ doping NCA cathode materials are prepared by the high-temperature solid-state method. The results show that 0.5%Ti-NCA has a lower cationic mixing degree and better cycling performance. The capacity retention rate of 100 cycles is 98.91% and 96.59% at current densities of 0.5 C and 1.0 C, respectively. The CV and EIS test results show that 0.5%Ti-NCA has lower polarization and higher lithium ion diffusion coefficient DLi+(8.43×10−14 cm2/S) after 100 cycles, while Pure-NCA only has 6.92×10−15 cm2/S, which effectively enhances the electrochemical properties of NCA cathode materials.

Experimental and theoretical investigation of an ionic liquid-based biphasic solvent for post-combustion CO2 Capture: Breaking through the “Trade-off” effect of viscosity and loading

To break through the “trade-off” effect of biphasic solvents between rich-phase viscosity and CO2 loading, we synthesized a novel ionic liquid (diethylenetriamine-3-hydroxypyridine, [DETA][3HPyr]) with multiple active sites and combined it with the organic solvent diethylene glycol monobutyl ether (DGME) and water to prepare a biphasic solvent for CO2 absorption, the best absorption condition was optimized. The results demonstrated that after absorption, the solvent transformed from homogeneous to biphasic with highly self-concentrated absorption products in the rich phase. The volume of the rich phase accounted for only 36.3 % of the total solvent, while its viscosity decreased significantly to 28.1 mPa·s, with a high blend absorption capacity of 2.67 mol·kg−1. The species of absorption product and absorption mechanism was investigated using 13C NMR. The stable presence of carbamic acid in the system was confirmed, contributing to enhanced absorption capacity. Density functional theory calculations revealed that DGME stabilized carbamic acid through intermolecular hydrogen bonding interactions, and highly polar ions generated during absorption and uneven charge distribution between ions dominated the phase-change process and increased the water content in the rich phase. Thermodynamic energy barrier calculation showed that the solvent effect of DGME reduced the Gibbs free energy barriers of proton transfer and facilitated reaction progress. 3IL4D3H exhibited excellent cyclic performance with low regeneration energy consumption at 1.77 GJ·t−1. This is the first work to revealing the intrinsic dynamics of carbamic acid formation, and provides a new perspective for the phase-change mechanism of ionic liquid-based biphasic solvent.

Numerical analysis of the viscosity of ZrF4–BeF2 molten salts for nuclear transmutation using fusion neutron sources

This study analyzed the influence of ZrF4 on the viscosity of a ZrF4–BeF2 binary salt towards developing BeF2-based molten salts for nuclear transmutation targets. Specifically, we performed molecular dynamics simulation using a polarization ion model and evaluated the viscosity, static structure, and applicability of the Stokes–Einstein equation for ZrF4–BeF2 compared with LiF–BeF2. Our study revealed that ZrF4–BeF2 exhibits higher viscosity than LiF–BeF2 because each ionic bond's longer lifetime extends the structural relaxation time. Furthermore, it is suggested that the ZrF and BeF relaxations contribute to the viscosity mechanism of ZrF4–BeF2. Most of the elements in long-lived fission products (LLFPs) are multivalent ions such as Zr, Pd, and Sn, which bind strongly to anions and are not expected to contribute much to reducing the viscosity of BeF2 mixed salts. In contrast, Cs, also an LLFP, is a monovalent ion, and CsF can reduce the viscosity of these salts. Mixing particular LLFPs with CsF will be one of the principles in designing BeF2-based salts for transmutation.

Large Polarization Near 50 μC/cm2 in a Single Unit Cell Layer SrTiO3.

The generally nonpolar SrTiO3 has attracted more attention recently because of its possibly induced novel polar states and related paraelectric-ferroelectric phase transitions. By using controlled pulsed laser deposition, high-quality, ultrathin, and strained SrTiO3 layers were obtained. Here, transmission electron microscopy and theoretical simulations have unveiled highly polar states in SrTiO3 films even down to one unit cell at room temperature, which were stabilized in the PbTiO3/SrTiO3/PbTiO3 sandwich structures by in-plane tensile strain and interfacial coupling, as evidenced by large tetragonality (∼1.05), notable polar ion displacement (0.019 nm), and thus ultrahigh spontaneous polarization (up to ∼50 μC/cm2). These values are nearly comparable to those of the strong ferroelectrics as the PbZrxTi1-xO3 family. Our findings provide an effective and practical approach for integrating large strain states into oxide films and inducing polarization in nonpolar materials, which may broaden the functionality of nonpolar oxides and pave the way for the discovery of new electronic materials.

High-energy CID tandem TOF-MS of various types of precursor ions of selected diether phospholipids: Diagnostic known and unexpected fragmentation pathways

The fragmentation behavior of some selected synthetic (1,2-diphytanyl- and 1,2-dihexadecyl-glycerophosphatidylethanolamine, 1,2-diphytanyl- and 1,2-dihexadecyl-glycerophosphatidylcholine) as well as of one natural diether phospholipid (2,3-diphytanyl-glycerophosphatidylinositol), the latter obtained from extracts of the archaeon Sulfolobus acidocaldaricus, was described by negative- and positive-ion MALDI high-energy CID tandem time-flight mass spectrometry for the first time. In contrast to the fragmentation pathways of classical diester glycerophospholipids, whose fragmentation behavior is already well described, the investigated diether glycerophospholipids exhibited a very different fragmentation behavior. The [M–H]−-precursor ions (ethanolamine, inositol) showed abundant high-mass charge-remote site fragmentation of the alkyl chains with easy determination of all methyl branching points (if present). Corresponding low mass product ions elucidated the identity of the polar head group. In contrast, [M+H]+-precursor ions of ethanolamine derivatives showed unusual loss of H3PO4 directly from the precursor ion and McLafferty-like rearrangements of selected product ions differing between sn1-and sn2-substituents, [R1O+58]+ and [R2O+42]+ ions, respectively. No diagnostic low mass product ions or high mass charge-remote site fragmentations are observed. A yet undescribed rearrangement reaction for protonated diether phosphocholine derivates was found by an intramolecular transesterification rearrangement of the precursor ion forming protonated O-alkyl glycerophosphatidylcholine. Besides, high mass charge-remote site fragmentation of the alkyl chains was observed. High-energy CID-spectra of [M+Na]+-precursor ions showed only little fragmentation (ethanolamine, inositol) with abundant partial polar head group losses and low mass head group product ions. In contrast, the [M+Na]+-precursor ions of corresponding choline derivatives showed significant charge-remote site fragmentation of the alkyl chains and diagnostic low mass head group ions. In case of the ethanolamine derivatives the [M+2Na–H]+-precursor ions exhibited abundant polar head group losses and high mass charge-remote site fragmentation with diagnostic low mass head group product ions. The inositol derivative mainly yielded disodiated dehydrated inositol phosphate as product ions. Finally, two diether phospholipid-specific product ions, the newly described K- and L-type ions, are described for the first time for all lipid derivatives and their mechanism of formation is described in detail.

Near-Zero Energy Consumption Capacitors by Controlling Inhomogeneous Polarization Configuration.

Taking into account the need for energy conservation, achieving near-zero energy loss, namely ultrahigh efficiency (η), in energy storage capacitors with large recoverable energy storage density (Wrec) plays an important role in applications, which is one of the major challenges in dielectric energy storage field. Here, guided by phase-field simulation, inhomogeneous polarization configuration with multiple symmetries and polarization magnitudes is controlled through aliovalent strongly polar double ion design to establish a strongly disordered state. A record-high η of ≈97.4% is realized in lead-free relaxors with a large Wrec of ≈8.6 J cm-3, which also give a giant Wrec of ≈11.6 J cm-3 with an ultrahigh η of ≈96.1% through high-energy ball milling, showing a breakthrough progress in ceramic capacitors with a maximum figure of merit of 330. This work demonstrates that controlling inhomogeneous polarization configuration is an effective avenue to develop new high-performance near-zero energy loss energy storage capacitors.

Implementing of Fourier Deconvolution Multiplexing to Fast Polarity Switching Miniaturized Ion Mobility Spectrometer.

Ion mobility spectrometry (IMS) is a reliable and sensitive technique for the detection and analysis of compounds at the trace level. Depending on the chemical composition of the sample, compounds may be positively or negatively charged to form different polarity ions and detected in positive or negative polarity of the electric field. In order to detect multiple threats simultaneously with miniaturized devices, using a single detection unit to achieve high resolving power and high sensitivity is important. In this work, a miniaturized drift tube with fast polarity switching capabilities integrated with Fourier deconvolution multiplexing techniques is proposed for the first time as a means to improve the performance of ion mobility spectrometry. The sensitivity and resolving power are improved compared to traditional polarity switching signal averaging data acquisition methods. The displayed device had a high resolving power up to 52 at a drift length of 41 mm and a drift tube voltage of 2 kV. Trinitrotoluene (TNT), methamphetamine (MA), benzene, toluene, methyl tert-butyl ether (MTBE), acetic acid, and methylene chloride were evaluated using the proposed fast polarity switching multiplexing spectrometer and exhibited satisfied performance.

Co-Action of Ionic Liquids with Alternative Sorbents for Removal of Reactive Azo Dyes from Polluted Wastewater Streams

In this study, the facile removal of the chromium-complex-based reactive azo dye C. I. Reactive Black 8 (RB8) from model wastewaters by the co-action of alternative sorbents—biochar (BC) and bentonite (BT)—with ionic liquids such as benzalkonium chloride (BAC) or Aliquat 336 (A336) was studied. The experiments using model RB8-containing wastewater proved that the co-action of BAC with BC is the most promising method of RB8 separation from wastewater containing 1 g L−1 of RB8 dye. The application of 2 g L−1 BC in co-action with 1.5 g L−1 BAC or 1 g L−1 BT in co-action with 2 g L−1 BAC enables the removal of more than 98% of contaminant RB8 after 30 min of action. Similar removal efficiency (RE) was achieved using 40 g L−1 of powdered activated carbon (PAC) after 180 min of action. To reach the same RE using real RB8-containing wastewater, a four times higher dose of BC and a four times higher dose of BAC per gram of removed RB8 were required. The proposed mechanism of RB8 removal by the co-action of alternative sorbents with BAC comprises a parallel effect of (i) sorption, (ii) the formation of less polar ion pairs accompanied by their sorption on an alternative sorbent and (iii) the separation of used alternative sorbents covered with ion pairs. The removal efficiency of organic contaminant(s) from both model and real wastewater was evaluated by VIS spectroscopy applying the Lambert–Beer law and by the determination of chemical oxidation demand (COD) and/or adsorbable organically bound halogen (AOX) parameters.

Strongly Enhanced Polarization in a Ferroelectric Crystal by Conduction-Proton Flow.

Ion conductors comprising noncentrosymmetric frameworks have emerged as new functional materials. However, strongly correlated polarity functionality and ion transport have not been achieved. Herein, we report a ferroelectric proton conductor, K2MnN(CN)4·H2O (1·H2O), exhibiting the strong correlation between its polar skeleton and conductive ions that generate anomalous ferroelectricity via the proton-bias phenomenon. The application of an electric field of ±1 kV/cm (0.1 Hz) on 1·H2O at 298 K produced the ferroelectricity (polarization = 1.5 × 104 μC/cm2), which was enhanced by the ferroelectric-skeleton-trapped conductive protons. Furthermore, the strong polarity-proton transport coupling of 1·H2O induced a proton-rectification-like directional ion-conductive behavior that could be adjusted by the magnitude and direction of DC electric fields. Moreover, 1·H2O exhibited reversible polarity switching between the polar 1·H2O and its dehydrated form, 1, with a centrosymmetric structure comprising an order-disorder-type transition of the nitrido-bridged chains.

(Invited) Potentiometric Entropy Measurements and Isothermal Operando Calorimetry to Identify the Charging Mechanisms of Battery Materials

This talk presents recent development in potentiometric entropy measurements and isothermal operando calorimetry to gain insight into the charging mechanisms of lithium ion batteries. First, the concept, design, and operation of two unique experimental apparatuses will be presented. Then, the effects of material composition, crystallographic structure, and particle size on the cell’s thermodynamic behavior, polarization, and lithium ion transport will be discussed for different Wadsley-Roth materials (e.g., TiNb2O7, PNb9O25, (W0.2V0.8)3O7) under quasi-equilibrium conditions. Particular attention will be paid to phase transition, lithium ion intercalation and ion ordering in solid solution, and/or two-phase coexistence occurring during charging/discharging. Finally, instantaneous heat generation rates measured by isothermal operando calorimetry at each electrode will be used to identify the causes of energy dissipation and to provide insight into the transport and interfacial phenomena taking place in the electrodes at different states of charge and charging rates. Here, special emphasis will be placed on the contributions of Joule heating associated with resistive losses, heat of mixing due to ion concentration gradient, and reversible entropic changes.

Crystal structure, lattice energy and microwave dielectric properties of melilite-type Ba1-xSrxCu2Ge2O7 ceramics

The Ba1-xSrxCu2Ge2O7 was successfully obtained through the solid-state reaction method, with single-phase BaCu2Ge2O7 formed at 850 °C. Scanning electron microscopy analysis revealed the excellent chemical compatibility of Ba1-xSrxCu2Ge2O7 with silver. The properties of Ba1-xSrxCu2Ge2O7 ceramics were explained using the P-V-L theory. The εr-corr decreased with the polarization rate (Σχu*Nbu) and ion polarization of the unit cell. The Q×f increased with the chemical bond strength and lattice energy (Ucal), particularly the lattice energy of the Ge-O bond (U(Ge-O)). The τf exhibited an opposite trend to the Q×f value and was influenced by the U(Cu-O) and susceptibility of the Cu-O bond (χ(Cu-O)). Sintering at 875 °C for 3 h yielded optimal microwave dielectric performance for Ba1-xSrxCu2Ge2O7 ceramics, with observed values of εr = 9.26 ± 0.14, Q×f = 85,660 ± 4200 GHz, and τf = −15.6 ± 1.1 ppm/°C at x = 0.10. These promising microwave dielectric properties make Ba1-xSrxCu2Ge2O7 a potential candidate for LTCC material applications.

Structural criticality manifested by a polarized ionic layer on a MWCNT yarn surface under mechanical loading

The electrochemical capacitance of an energy harvester based on a multiwalled carbon-nanotube yarn is proportional to the total strain and then rapidly decreases after the strain exceeds a critical value. Rigorous characterization of the nonlinearities in the distortion of the polarized ion layer under an external load is necessary to systematically optimize the performance of energy-harvesting fibers. In this study, we conducted electrochemical experiments and all-atom molecular dynamics simulations to elucidate the dynamics of an ionic polarization layer on a nanotube surface. The in-plane compressive strain exerted under the mechanical tension of the energy harvester induced the radial buckling of the nanotubes, which in turn became the driving force behind the repulsion between adjacent polar ion layers. Therefore, electrochemical stability was guaranteed only under structural stability and the resulting elastic deformation experienced by each nanotube. The proposed mechanism reveals the available mechanical range wherein the polarized ionic layers can substantially function in chemomechanical energy conversion.

Linear Ion Trap Mass Spectrometer (LITMS) Instrument Field and Laboratory Tests as Part of the ARADS Field Campaigns.

The highly compact Linear Ion Trap Mass Spectrometer (LITMS), developed at NASA Goddard Space Flight Center, combines Mars-ambient laser desorption-mass spectrometry (LD-MS) and pyrolysis-gas chromatography-mass spectrometry (GC-MS) through a single, miniaturized linear ion trap mass analyzer. The LITMS instrument is based on the Mars Organic Molecule Analyser (MOMA) investigation developed for the European Space Agency's ExoMars Rover Mission with further enhanced analytical features such as dual polarity ion detection and a dual frequency RF (radio frequency) power supply allowing for an increased mass range. The LITMS brassboard prototype underwent an extensive repackaging effort to produce a highly compact system for terrestrial field testing, allowing for molecular sample analysis in rugged planetary analog environments outside the laboratory. The LITMS instrument was successfully field tested in the Mars analog environment of the Atacama Desert in 2019 as part of the Atacama Rover Astrobiology Drilling Studies (ARADS) project, providing the first in situ planetary analog analysis for a high-fidelity, flight-like ion trap mass spectrometer. LITMS continued to serve as a laboratory tool for continued analysis of natural Atacama samples provided by the subsequent 2019 ARADS final field campaign.

Flexible TiVCTx MXene film for high-performance magnesium-ion storage device

Magnesium-based battery system has emerged as the potential candidate to beyond Li-ion battery system due to the numerous advantageous of magnesium anode, such as natural abundance, high capacity and dendrites free. However, the selection of cathode materials and the intercalation of magnesium-ions in the cathode host material remains a challenge due to the strong interaction of highly polar divalent magnesium ions with the cathode material, making the diffusion of magnesium ions relatively difficult. Herein, the flexible TiVCTx MXene film was developed via a facile and economical approach. As the cathode host material for magnesium-ion storage, the freestanding TiVCTx MXene film displays a high specific capacity of 111 and 135 mAh g−1 at a current density of 0.05 A g−1 for magnesium-ion batteries (MIB) and Mg/Li hybrid batteries (MLHB). Furthermore, a long-term cycling stability over 1000 cycles was demonstrated and a detailed investigation of the unique long activation phenomenon of MXene films during cycling. More importantly, the reaction mechanism of magnesium-ion storage was validated, i.e., the MXene interlayer spacing variation with the reversible Mg2+ diffusion behavior. This work reveals the magnesium storage mechanism of MXene materials and provides a new pathway for high-performance storage of magnesium-ion cathode materials.