Cavity Electrode Research Articles

An Undergraduate Practical for Evaluation of Powdery Battery Materials with a Metallic Cavity Electrode

An Undergraduate Practical for Evaluation of Powdery Battery Materials with a Metallic Cavity Electrode

Facile Synthesis of U2Ti Intermetallic by Direct Electrochemical Reduction of UO2-TiO2 Composite in LiCl-Li2O Melt

Alloys of U with Ti are of importance in nuclear industry as fuel for Gen IV fast reactors, hydrogen isotope storage medium for fusion reactors, super conductors, and also as corrosion resistant material for use in various applications. Here, preparation of U2Ti intermetallic compound was investigated by the direct electrochemical reduction of mixed oxide of UO2-TiO2 in LiCl-0.5% Li2O molten salt at 650 °C. The mixed oxide pellet of UO2-TiO2 sintered at 1500 °C was found to be a mixture of UTi2O6 and UO2 as evidenced by X-ray diffraction (XRD) analysis. Direct electro-lithiothermic reduction of UO2, TiO2, and a mixture of sintered UO2-TiO2 and UTi2O6 coupled with cyclic voltammetry of these oxides in the melt was performed to understand the electro-reduction mechanism. Potentials of reduction of these oxides in the melt, w.r.t Ni/NiO reference electrode, obtained by analysis of CV data of these oxides contained in metallic cavity electrodes and XRD analysis of partially electro-reduced oxides were used to arrive at the electro-reduction mechanism. Results indicate that U2Ti can be prepared conveniently by the electro-lithiothermic reduction of sintered pellet of UO2-TiO2 cathode by constant current electrolysis in a two-electrode cell.

Electrochemical Preparation of Ti2CrV Alloy in CaCl2 Melt

Ti2CrV alloy shows good hydrogen storage characteristics at room temperature and ambient pressure. The present study investigated the feasibility of direct electrochemical reduction of TiO2-Cr2O3-V3O5 to Ti2CrV in CaCl2 melt at 900 °C by the FFC Cambridge process. The electrolysis was conducted in a two-electrode assembly with the sintered mixed oxide cathode and HD graphite anode at a constant cell voltage of 3.1 V for different time intervals to elucidate the reduction mechanism of the metal oxide mixture. The obtained products were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques. Cyclic voltammetry studies using metallic cavity electrode containing mixed metal oxide powder were also carried out to determine the electrochemical reduction behavior in CaCl2 melt at 900 °C. It was observed that the presence of pre-formed Cr and V metal in the vicinity of titanium oxide helped in its faster reduction. The complete metallization of the sintered mixed oxide pellet occurred after 15 h of electrolysis. The electrochemical reduction mechanism was observed to proceed through various intermediates such as chromium-rich Cr-V, vanadium-rich V-Cr, CaTiO3, TiO, Ti6O, Ti-V, and C15-TiCr2.

High speed surface acoustic wave and laterally excited bulk wave resonator based on single-crystal non-polar AlN film

One approach to extend the acoustic applications of aluminum nitride (AlN) in the GHz frequency range is to take advantage of the piezoelectric performance and high acoustic velocity (∼11 350 m/s) along the c-axis of this material. In particular, in the case of high-frequency micro-electromechanical systems, it should be possible to simplify the construction of resonators by using a-plane AlN-based structures. In the work described in this Letter, a single-crystalline a-plane AlN layer on an r-plane sapphire substrate is obtained by combining sputtering and high-temperature annealing. Based on this non-polar AlN, a resonator with only planar interdigital transducer electrodes is fabricated. Experiments on this resonator reveal simultaneous excitation of an anisotropic Rayleigh surface acoustic wave (SAW) at 2.38 GHz and a laterally excited bulk acoustic wave (LBAW) at 4.00 GHz. It is found that the Rayleigh SAW exhibits outstanding performance, with a quality factor as high as 2458 and great stability under variations in temperature. The LBAW at 4.00 GHz is excited by pure planar interdigitated electrodes without the need for any cavity or bottom electrode structure, thus demonstrating a promising approach to the construction of high-frequency resonators with a relatively simple structure.

The Influence of Cavity Size and Location Within Insulation Paper on the Partial Discharge Activities

This paper examines the influence of cavity size and location in the insulation paper on the Partial Discharge (PD) activities through Finite Element Method (FEM). The model consisted of a conductor wrapped with insulation paper. Two different locations of the spherical cavities were introduced in this study, namely Location 1 (L1) and Location 2 (L2), located at the center and left corner of the insulation paper. The model introduced two different sizes of cavities with diameters of 0.5 mm and 0.8 mm. An AC voltage source of 17 kV, 50 Hz, was applied at the conductor while the bottom of the insulation paper was grounded. The real and apparent PDs were obtained by integrating the current flowing through the cavity and ground electrode with the respective surface area. The simulation was carried out for 100 cycles. The resultant model was used to study the PD occurrence, magnitude, and Phase Resolved Partial Discharge (PRPD) within the insulation paper. It is found that the large cavity size produces a lower number of PD occurrences per cycle than the small cavity size. The large cavity size produces a higher charge magnitude as compared with the small cavity size. The PD occurrence per cycle and charge magnitude are higher for the cavity location at L1 compared to L2. The PRPD yields the same pattern for cavity location at L1 and L2, whereby the differences are only on the charge magnitude and PD occurrence per cycle.

Studies on Preparation of Thorium-Based Intermetallics in CaCl2 Melt by Electrochemical De-Oxidation Process

Thorium and its alloys find immense applications in nuclear technology. In the present study, the feasibility of direct electrochemical de-oxidation of mixed ThO2-NiO (7:3 molar ratio) and ThO2-Fe2O3 (7:1.5 molar ratio) to Th7Ni3 and Th7Fe3 intermetallics was investigated for the first time in CaCl2 melt at 900 °C using FFC Cambridge process. Electro-reduction mechanisms of the mixed metal oxides were elucidated by conducting constant voltage electrolysis at 3.1 V cell potential with sintered mixed metal oxides pellet cathode and HD graphite anode in molten CaCl2 for different time intervals. The electrolysed products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis techniques. Reduction of the less stable metal oxide, e.g., NiO or Fe2O3, occurred at the initial phase of electrolysis, and de-oxidation of more stable ThO2 took place in presence of newly formed metallic Ni or Fe in the later stage, leading to the formation of Th7Ni3 or Th7Fe3. Electro-reduction mechanism of ThO2 was evaluated using cyclic voltammetry technique with ThO2 filled Mo cavity electrode, and a single-step reduction of ThO2 to Th was perceived.

A comparative study on silicon-based negatrode materials in metallic cavity electrode and button half cell — Uncovering unseen microscopic and dynamic features

The electrochemical characterization of lithium storage materials using the button cell is commonplace, but it is also tedious and time-consuming. Also, the results are often affected by the use of the binders and separator membranes, and by the electrode forming and cell assembly methods. To study the changes in materials before and after dis-/charging, one has to break up the button cell and disturb the packing structure of electrode. In this work, the metallic cavity electrode made of copper (Cu-MCE) was used to study silicon-based negative electrode (negatrode) materials during electrochemical de-/lithiation. The initial apparent reaction area (i.e. the contacting area between the Cu substrate and the active materials, 0.785 mm2) of the Cu-MCE was much smaller than that of the half-button cell (153.86 mm2), reducing significantly the overall current and hence polarization in the Cu-MCE. Powders of commercial silicon and phosphorus-doped silicon (P-doped Si) were tested in the Cu-MCE and a conventional button cell. Cyclic voltammograms (CVs) recorded using the Cu-MCE showed full activation in the first cycle, unlike the button cell whose CVs expanded continuously beyond 5 cycles. Current peaks on the CVs of the Cu-MCE agreed with the expected redox reactions but were more pronounced. The subtle differences between P-doped Si and pure Si could also be revealed by the Cu-MCE with the current peaks becoming more obvious, apparently due to modification in material structures and improved ion transport dynamics. The peak currents on the CVs of the Cu-MCE were plotted against the square root of scan rate (v1/2), showing non-linearity for the two oxidation peaks at 0.35 and 0.54 V, indicating both diffusion and surface of the delithiation processes. Linear plots were obtained for the two reduction peaks at 0.165 and 0.245 V with comparable slopes (−0.024 and 0.029 mA mV−1/2 s1/2), confirming diffusion control with insignificant polarization. However, similar analyses of the button cell revealed diffusion control in both oxidation and reduction, indicating slower dynamics with large polarization to delithiation. More importantly, the Cu-MCE can be inspected directly after dis-/charging without any disturbance, and provides unseen variation in the packing structure, particle morphology, and elemental information of the active materials. It is hoped that the higher accuracy, better details, and greater efficiency offered by the Cu-MCE for studying the intrinsic electrode reaction characteristics of Si-based electrode materials can be extended to other powdery materials for charge storage.

Electrochemical Preparation of ZrFe2 and ZrFe1.8Ni0.2 Intermetallic Compounds by FFC Cambridge Process

The aim of the present study was to prepare ZrFe2 and ZrFe1.8Ni0.2 intermetallic compounds by FFC Cambridge process. The intermetallic compounds were prepared directly from the mixed oxide precursors, namely ZrO2-Fe2O3 and ZrO2-Fe2O3-NiO, respectively. Electrochemical de-oxidation experiments were carried out with mixed oxide pellet cathode and HD graphite anode by applying a constant cell voltage of 3.1 V in CaCl2 melt at 900 oC. The electrochemical behaviour of oxides was studied by cyclic voltammetry using metallic cavity electrodes (MCEs). The electrolysis was carried out for different durations of time to understand the mechanistic pathway of reduction of ZrO2-Fe2O3. The electro-reduced products were characterized by X-ray diffraction (XRD) technique, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The reduction intermediates involved Fe, CaZrO3, calcia stabilised zirconia (CSZ), Fe23Zr6, Zr6Fe3O and Zr2Fe. Single cubic C15 phase of ZrFe2 was obtained in 48 h electrolysis product. ZrFe1.8Ni0.2 was also electrochemically synthesized from its oxide precursors viz. ZrO2, Fe2O3 and NiO. Apart from ZrFe1.8Ni0.2 phase, the electro-reduced products had a Zr2Ni phase even after 72 h of electrolysis.

A novel design of a retarding field electron energy analyzer with a cavity electrode providing extremely high energy resolution

An electron energy analyzer based on the retarding electrostatic field generated by a cavity electrode was prototyped, where the designed energy resolution is smaller than 10 meV at acceleration voltages Vo less than 5 kV and a half angle spread θo less than 20 mrad for the incident electron beams with the scanning voltage range of 3 V. Precise energy resolution, however, has not been recognized experimentally because of the difficulties of equipping such a narrow energy spread electron source. This paper describes the principle of the newly developed energy analyzer and shows the obtained energy spectra from a Schottky emitter ZrO/W(100) with a tip of the curvature radius of 1.5 μm, which could highly reproduce the theoretically expected spectra at various emitter temperatures because of its predominantly thermal emission.

Iontophoresis effects of two-step self-etch and total-etch systems on dentin permeability and sealing of composite restoration under simulated pulpal pressure.

Studies demonstrated the bond strength enhancement and the decrease in degradation of the adhesive interface after applying either self-etch adhesives or two-step, etch-and-rinse adhesives under an electric field. However, the presence of dentinal fluid driven by the pulpal pressure in vivo is a profounding factor affecting both the sealing ability and bond strength of adhesives. This study aimed to evaluate the effect of three-step etch-and-rinse and two-step self-etch adhesives when applied with iontophoresis under simulated pulpal pressure on the permeability of dentin, resin infiltration, and the sealing ability of resin composite. The experiments were done on 32 recently extracted premolars, randomly assigned into four groups (n = 8) according to two adhesive systems (SBMP and SE), applied following the manufacturer's instructions (control) for two groups or with iontophoresis for the others (SBMPi and SEi). For the iontophoresis, the anodal current was applied at 75μA for 20s through the cavity electrode during the bond. The fluid flow rate of dentin was recorded after cavity preparation (smear-layer-covered dentin; T1), bonding (T2), and composite restoration (T3) during the maintained pulpal pressure of 20mmHg. The flow rates were expressed as a percentage relative to the initial smear-layer-covered value for each specimen. Results were analyzed using repeated measures ANOVA. Scanning electron microscopy (SEM) was performed to observe the resin/dentin interface. There were no significant increases in the mean flow rates from T1 to T3 in the SBMP (P = 0.355), while these changes in the SE were significant between T1 (100%) and T2 (166.77%) and T1 and T3 (221.16%) (P = 0.002; one-way RM ANOVA; Holm-Sidak test). For the iontophoresis groups, the mean flow rates decreased significantly from T1 to T2 and T1 to T3 of both SBMPi (T2 = 86.43, and T3 = 79.53; P < 0.001) and SEi groups (T2 = 87.96, and T3 = 81.48; P = 0.004). The iontophoresis of both adhesives produced the optimal resin infiltration with improved quality of the hybrid layer and resin tags. SBMP bonded with or without iontophoresis performed better sealing ability than SE under the same condition. Both adhesives applied with anodal iontophoresis significantly decreased the dentin permeability, contributing to the improved resin infiltration.

Simultaneous Joining and Forming of Dissimilar Steels by Electrically Assisted Pressure Joining

In the present study, simultaneous joining and forming of dissimilar steels Q235B (ball) and SCM435 (stud) by electrically assisted pressure joining (EAPJ) are experimentally investigated. The target product is intended with a dust‐cover ring in the stud head, then the electrodes and the stud head are designed accordingly so that the deformed stud head can fill the electrode cavity. In EAPJ, compressive deformation and pulsed electric current are simultaneously applied to the workpieces to create diffusion bonding. As a result, the sound solid‐state joints are successfully fabricated by EAPJ, while a target geometry is also successfully formed. In the bending test, the fabricated ball stud is broken through the ball, and the maximum bending load is higher than the target value for commercial applications. The microstructure analysis and hardness test show that the progress suggested in the present study can cause grain refinement, induce tempered martensite, and increase the portion of polygonal ferrite in the deformed zone (DZ), the joining zone (JZ), and the thermal‐mechanically affected zone (TMAZ), respectively. The results of the present study confirm that the concept of EAPJ is applicable to the simultaneous joining and forming of dissimilar steels.

Electrochemical Mechanism of Recovery of Nickel Metal from Waste Lithium Ion Batteries by Molten Salt Electrolysis.

With the widespread use of lithium-ion batteries, the cumulative amount of used lithium-ion batteries is also increasing year by year. Since waste lithium-ion batteries contain a large amount of valuable metals, the recovery of valuable metals has become one of the current research hotspots. The research uses electrometallurgical technology, and the main methods used are cyclic voltammetry, square wave voltammetry, chronoamperometry and open circuit potential. The electrochemical reduction behavior of Ni3+ in NaCl-CaCl2 molten salt was studied, and the electrochemical reduction behavior was further verified by using a Mo cavity electrode. It is determined that the reduction process of Ni3+ in LiNiO2 is mainly divided into two steps: LiNiO2 → NiO → Ni. Through the analysis of electrolysis products under different conditions, when the current value of LiNiO2 is not less than 0.03 A, the electrolysis product after 10 h is metallic Ni. When the current reaches 0.07 A, the current efficiency is 77.9%, while the Li+ in LiNiO2 is enriched in NaCl-CaCl2 molten salt. The method realizes the separation and extraction of the valuable metal Ni in the waste lithium-ion battery.

Phase Control of Co-Sn Alloys through Direct Electro-Deoxidation of Co3O4/SnO2 in LiCl-KCl Molten Salt

Co can form a series of intermetallic compounds with Sn which usually exhibit unique physical and chemical properties. However, it is a challenge to control the phase composition of Co-Sn alloys. Here, we attempted to prepare Co3Sn2, CoSn and CoSn2 from the mixture of Co3O4/SnO2 using electro-deoxidation. We investigated the effects of sintering temperature for the mixed oxide plate and electrolysis conditions, such as voltage, electrolysis time, and molten salt temperature on the electro-deoxidation process of Co3O4/SnO2. The electrochemical deoxidation mechanisms of Co3O4, SnO2, and Co3O4/SnO2 composites were also explored by cyclic voltammetry using metallic cavity electrode. The Co-Sn alloys with different phase compositions, such as Co3Sn2, CoSn, and CoSn2, were obtained through controlling the molar ratio between Co and Sn in the initial Co3O4/SnO2 plate and the molten salt temperature. The obtained Co-Sn alloys were used as anode materials for lithium-ion batteries which showed 123.0, 246.5, and 323.4 mAh g−1 for Co3Sn2, CoSn, and CoSn2, respectively.

Towards real-life EEG applications: novel superporous hydrogel-based semi-dry EEG electrodes enabling automatically ‘charge–discharge’ electrolyte

Objective. A novel polyacrylamide/polyvinyl alcohol superporous hydrogel (PAAm/PVA SPH)-based semi-dry electrode was constructed for capturing electroencephalogram (EEG) signals at the hairy scalp, showing automatically ‘charge–discharge’ electrolyte concept in EEG electrode development. Approach. In this regard, PAAm/PVA SPH was polymerized in-situ in the hollow electrode cavity by freezing polymerization, which acted as a dynamic reservoir of electrolyte fluid. The SPH can be completely ‘charged’ with electrolyte fluid, such as saline, in just a few seconds and can be ‘discharged’ through a few tiny pillars into the scalp at a desirable rate. In this way, an ideal local skin hydration effect was achieved at electrode–skin contact sites, facilitating the bioelectrical signal pathway and significantly reducing electrode–skin impedance. Moreover, the electrode interface effectively avoids short circuit and inconvenient issues. Main results. The results show that the semi-dry electrode displayed low and stable contact impedance, showing non-polarization properties with low off-set potential and negligible potential drift. The average temporal cross-correlation coefficient between the semi-dry and conventional wet electrodes was 0.941. Frequency spectra also showed almost identical responses with anticipated neural electrophysiology responses. Significance. Considering prominent advantages such as a rapid setup, robust signal, and user-friendliness, the new concept of semi-dry electrodes shows excellent potential in emerging real-life EEG applications.

Design and analysis of piezoelectric micromachined ultrasonic transducer using high coupling PMN-PT single crystal thin film for ultrasound imaging

Due to its higher frequency, improved impedance matching, and easy formation of array, piezoelectric micromachined ultrasonic transducer (PMUT) has drawn much attentions for application in ultrasound imaging. In this paper, PMUT based on [011] poled 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 (PMN-0.30PT) single crystal thin film was proposed and modeled by performing finite element method. Influences of different configurations of top electrode shape and bottom cavity shape on PMUT performance were studied. The investigation results show that the resonant frequency of PMN-PT-based PMUT with circular top electrode and square bottom cavity is up to 27.155 MHz. The effective electromechanical coupling coefficient ( of PMUT was up to 2.32%, which was 127% larger than that of lead zirconate titanate-based PMUT. The static transmitting sensitivity was three times enhancement compared to PMUT with square top electrode and square bottom cavity. Furthermore, acoustic field characteristics of PMUT and PMUT arrays based on PMN-PT in water were investigated. The relative pulse-echo sensitivity level of 2 × 2 PMUT array was −35 dB with the reflector at 200 μm. The obtained results demonstrated that the proposed PMN-PT-based PMUT can achieve high frequency and large as well as considerable sensitivity, which is promising for application in high resolution ultrasound imaging.

Synthesis of Zn-Zr and Zn-Zr-Mg Alloys from Mixed ZnO-ZrO2 and ZnO-ZrO2-MgO in CaCl2-NaCl Molten Salt at 873 K

Zinc alloys are promising for wide uses thanks to their moderate biodegradability, good mechanical properties, and relevant biocompatibility. In this study, Zn-Zr and Zn-Zr-Mg alloys were prepared through the electro-deoxidation of ZnO-ZrO2 and ZnO-ZrO2-MgO mixtures in CaCl2-NaCl molten salt at 873 K. The electrochemical reduction mechanisms of ZnO, ZrO2, ZnO-MgO, and ZrO2-MgO composites were studied by cyclic voltammetry using metal cavity electrodes. The electrolysis parameters, such as the molar ratio of raw oxides and electrolysis time were also investigated. The results revealed promoted the reduction of ZrO2 and MgO through the formation of Zn and Ca-Zn alloys. Meanwhile, high melting point Zr and Zn-Zr alloys were found important in collecting more Zn and Zn-Mg alloys. A complete reduction of ZnO-ZrO2 and ZnO-ZrO2-MgO mixtures was achieved at ZnO contents above 2/3 of the total mass. Also, Zn, Zr, and Mg elements were homogeneously dispersed in the electrolyzed samples. In sum, the proposed method looks promising for the preparation of novel zinc-based alloys.

Preparation of Mg-Zr alloys through direct electro-deoxidation of MgO-ZrO2 in CaCl2-NaCl molten salt

The electro-deoxidation of MgO does not proceed efficiently due to the electrical insulation properties of MgO and large molar volume of metallic magnesium. In this experiment, an attempt was done to prepare Mg-Zr alloy from their oxides using the method of electro-deoxidation. The electrochemical mechanism of the deoxidation process of MgO, ZrO2 and MgO-ZrO2 composite was studied through cyclic voltammetry using metallic cavity electrode (MCE). There was an intermediate phase (Zr3O) in the reduction process of ZrO2. The electro-deoxidation of MgO occurred for MgO-ZrO2 composite in CaCl2-NaCl molten salt. Moreover, the electro-deoxidation of MgO was promoted by the addition of polyvinyl butyral (PVB). The formation of metal phase Mg was confirmed by XRD, EDS, Raman spectroscopy, and inductively-coupled plasma spectroscopy. The electro-deoxidation products showed significant differences with the concentration of PVB and the ratio between MgO and ZrO2. The electro-deoxidation of MgO and ZrO2 was favorable when the PVB concentration was 5.0% (wt.%). Pure metal phase of Mg-Zr alloys was formed when the molar ratio of MgO and ZrO2 was 1:2. The atomic fraction of Mg in the electrolytic product was ca. 28.0 mol.%. This work shows that MgO could be directly electro-deoxidized to Mg without the formation of intermediate phase oxide.

Study on the molybdenum electro-extraction from MoS2 in the molten salt

In this study, the electrochemical behavior of MoS2 in NaCl-KCl eutectic system was revealed by transient electrochemical techniques, using a homemade Mo metallic cavity electrode (MCE). In order to investigate the difference between MoS2 and molybdenum free ions in the molten salt, a metallic molybdenum electrode was electro-dissolved into the electrolyte in the form of molybdenum ions. The valence of molybdenum free ions was estimated to be in form of Mo6+ through the XPS analysis. The results of the electrochemical tests show that the reduction steps for MoS2 in NaCl-KCl salt was two and the corresponding reduction potentials were −0.37 V and −0.65 V (vs. Pt), respectively. A three-step reduction was found while investigating molybdenum free ions and the corresponding reduction potentials were 0.15 V, −0.40 V and −0.54 V (vs. Pt), respectively. The results of electrochemical impedance spectroscopy (EIS) analysis on the MoS2 pellet show a decreasing resistance with the increasing of potential. Moreover, potentiostatic electrolysis processes under different potentials were also carried out. Na2Mo3S4 was found to be the intermediate product during the reduction of MoS2 and Mo powder with residual sulfur content of 372 ppm was obtained as the cathode product after the electrolysis under 2.60 V for 20 h. At the same time, elemental sulfur was collected as the anodic product with a self-design condense apparatus.

Electro-reduction processes of U3O8 to metallic U bulk in LiCl molten salt

U3O8, the most stable state of uranium oxides, is a key intermediate compound for pyroprocessing of used nuclear fuel. However, compared to UO2, the electro-deoxidation mechanism of U3O8 is still cursory due to the complicated U-O intermediate phases. In this paper, the electro-deoxidation processes of U3O8 were investigated via diverse methods. A molybdenum metallic cavity electrode loaded with U3O8 powder was adopted to investigate the electrochemical behavior via cyclic voltammetry and square wave voltammetry. Sintered U3O8 pellets were used as cathodes to obtain electrolytic products with varying applied voltages or duration time. The composition and microstructure of electrolytic products were characterized by Raman spectroscopy, X-ray diffraction, scanning electron microscope and energy dispersive spectrometer. Based on above analysis results, electro-reduction processes of porous U3O8 pellets were proposed. First, U3O8 undergoes a rapid transition to U4O9 (U4O9-y). Then, the intermediate compound was gradually reduced to UO2 from the outer layer to the center of the bulk due to the limited migration rate of O2−. Before the transformation completed, metallic U generated on the surface of the bulk through direct electro-deoxidation and Li metal thermal reduction. With the increase of porosity and the propagation of metal-oxide-electrolyte three-phase interline, the U3O8 pellet was finally reduced to metallic U bulk.

Poly(benzoquinonyl disulfide) as an Active Material for Both Lithium and Magnesium Batteries

The undeniable benefit of lithium-ion (LIB) batteries for the development of a more environmentally friendly economy was recognized by the 2019 Nobel Prize in Chemistry. However, relying only on LIBs to energy storage will put considerable strain on lithium and cobalt resources used in these batteries. Therefore, alternative battery technologies other than LIBs are desirable to satisfy our growing demand for energy. Magnesium-ion batteries offer many distinct advantages over LIBs, including the high earth-abundance of magnesium, its high energy density and reversible dendrite-free deposition1. Organic materials are receiving an increasing amount of attention as electrode materials for future post lithium-ion batteries due to their versatility and sustainability2. In order to propose organic cathode with both high potential and specific capacity, new polymer based on hydroquinone sulfide, poly(benzoquinone disulfide) (PBQDS), were prepared in order to apply in both lithium and magnesium batteries. Diglyme and sulfolane with both LiTFSI and Mg(TFSI)2 were selected in order to evaluate the entire potentiality of the active material3. First of all, the electrochemical responses of PBQDS in lithium and magnesium based electrolytes was performed in a cavity electrode. The shapes of the cyclic voltammetry curves (Figure 1) are very close in term of potential and ΔEpeak in both lithium and magnesium systems at a relative high scan rate i.e. 1 mV s-1. An improvement of the redox couple reversibility seems to be observe in Mg form, with a ΔEpeak= 400 mV at a potential of 0.3 V vs Fc+/Fc (near 3.5 vs Li+/Li). Promising first results were obtained with PBQDS using glyme + LiTFSI electrolyte, in a coin cell configuration, indeed a stable capacity of 160 mAh g-1 was obtained at C/10 after 70 cycles, whereas 120 mAh g-1 was obtained at C in glyme based electrolyte. In order to improve, the electrochemical performances, especially at high C-rate, the particle size was reduced by controlled grinding. The effect of the PBQDS particle size on the electrochemical performances was under process. The electrochemical investigations in both Mg and Li based electrolytes will be presented in regard to the electrolyte nature and the PBQDS morphology. H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, D. Aurbach, Energy Environ. Sci., 2013, 6, 2265–2279.Poizot, F. Dolhem, Energy Environ. Sci., 2011, 4, 2003H. Dong, Y. Liang, O. Tutusaus, R. Mohtadi, Y. Zhang, F. Hao, Y. Yao, Joule 2019, 3, 1–12 Figure 1