Using Density Functional Theory based modeling, we compare sodium attachment to disodium terephthalate (Na2Tph) and a related molecule disodium pyridine dicarboxylate (Na2PDC). We predict that substitution of the Na2Tph’s aromatic ring with pyridine will lead to an increased voltage by about 0.4 V vs Na2+xTph up to Na2+1PDC and a similar voltage to the terephthalate between Na2+1PDC and Na2+2PDC, i.e. a two-plateau behavior vs. a single plateau for Na2+xTph.

The role of experimental parameters on direct oxidation of nickel foams with anodic oxidation (anodization) in molten KOH and their contribution to capacitance properties are investigated. Temperature of the melt exhibited an important role on the nature of compounds formed by anodic oxidation. On the samples anodized at 280 and 300 °C stoichiometric NiO is formed. Samples anodized in the temperature range of 150-200 °C gave very high maximum currents in CV measurements indicating the formation of electroactive nickel compounds on them. The nature of these compounds is determined as alpha nickel oxy-hydroxide (a-Ni(OH)2) by micro Raman, XRD and FT-IR measurements. Other property that determines the capacity of these electrodes is the morphology of the electroactive layer, which is controlled mainly by the duration of the treatment. 30 minutes of anodic oxidation time is determined as the optimum value. Areal capacity of the samples anodically oxidized at 200 °C for 30 min using 0.8 V cell voltage are determined as 2.73 F.cm-2 and 1.58 F.cm-2 for 1 mA.cm-2 and 20 mA.cm-2 discharge current densities respectively.

In this work we report the electrodeposition parameters of Sn-graphene films in aqueous solutions and silicon films in propylene carbonate. The galvanostatic electrodeposition of tin-graphene films from a sulfate-based acidic solution on copper substrates has been studied evaluating the effect of stirring on the morphology and the electrochemical performance. SEM analysis of films deposited galvanostatically at -10 mA.cm−2 for 20 minutes at 25 °C reveals that electrodeposition is suitable to generate continuous and homogeneous films with thickness values in the micrometer range. XRD analysis shows many intermetallic Cu-Sn crystalline phases are formed, as opposed to a pure amorphous tin layer. So far, electrochemical characterization has only been performed over a short number of charge-discharge cycles. The galvanostatic electrodeposition of silicon from propylene carbonate in galvanostatic mode has been carried out, but is currently extremely challenging to obtain continuous and homogeneous films. The XRD characterization has suggested the possible presence of amorphous phases in the films deposited at -1.0 mA.cm-2 for 30 minutes at 25 °C.

The present paper examines nanoporous material – carbon fabrics, which is used as electrodes in rechargeable energy storage capacitors (ultracapacitors). The fabrics structure, impurities composition, the influence of impurity types on ultracapacitor characteristics and the influence of thermal treatments on the impurities concentration are studied. The analysis of the ultracapacitor equivalent circuit with the studied material is made and the capacitor charge-discharge characteristics are investigated.

The performed studies resulted in determination of the investigated carbon material structure, determination of impurities composition of carbon material and change of impurities content depending on thermal treatment in vacuum. The optimum temperature range for treatment in vacuum is established. The equivalent circuit of the ultracapacitor is analyzed and its charge-discharge characteristics are investigated. The chosen equivalent circuit makes it possible to estimate the influence of pores different size on the ultracapacitor charge-discharge characteristics that is important for its application in energy storage devices.

We report the capacitance of entangled carbon nanotubes (CNTs) synthesized on flexible carbon fabric via water-assisted chemical vapor deposition. The CNTs were grown at atmospheric pressure with iron (Fe) as the catalyst, ethylene (C2H4) and 5%/95% H2/Ar as precursor gasses, and aluminum oxide as a buffer/barrier layer. The effect of the catalyst thickness (5 and 10 nm) on the specific capacitance was studied. The capacitance behavior of CNTs was evaluated by cyclic voltammetry measurements via a three-electrode system. The highest specific capacitance, approximately 56 F/g, was obtained for electrodes with 5nm Fe thickness. A nearly rectangular shaped cyclic voltammogram was exhibited for the CNTs grown on the carbon fabric. A specific power density of 0.012 KW/Kg and specific energy density 0.15 Wh/Kg were calculated from the galvanic charge/discharge (CD) curves. In addition, electrochemical impedance spectroscopy (EIS) revealed a characteristic supercapacitive behavior with a low equivalent series resistance of 7 Ωcm2.

To promote the energy density of lithium-ion battery, the sulfur-based cathode has attracted extensive attention because of its high specific capacity of 1672 mAh g-1 and its high abundance. However, the sulfur shuttling effects and the loss of active material during lithiation hinder its commercial application. To tackle these issues, we synthesized a stable copolymer-sulfur composite by chemically binding sulfur. The composite with 86% sulfur content was prepared using 1,3-diethynylbenzen and sulfur particles via scalable invers vulcanization. The sulfur content in copolymer sulfur was achieved as high as 86%. Our copolymer-sulfur composite cathode showed excellent cycling performance with a specific capacity of 454 mAh g-1 at 0.1 C after 300 cycles. We demonstrate that the organosulfur-DEB units in the copolymer-sulfur composite serve as the ‘plasticizer’ to effectively prevent the polysulfide shuttling.

We have investigated the diffusion mechanisms of Li-ion in amorphous lithium phosphite (LiPO3) with the addition of sulphur. By applying the nudge elastic band (NEB)1 method in crystal LiPO3 and Li3PO4, we have confirmed the ease in diffusion pathways for Li ions in LiPO3 which is quite consistent with the previous theoretical finding. From our diffusion study in 0.5 Li2O- 0.5 P2O5 and 0.4 Li2SO4 –0.6 (Li2O-P2O5) melts above 3000K investigated with ab-initio molecular dynamics (AIMD) has been confirmed by experiments at lower temperatures, we have demonstrated the benefit of S addition in increasing the Li+ mobility. We have also found that the Li2SO4 addition into the glass result in a characteristic shift in Li-ion vibration to a lower vibrational frequency. In addition, the presence of oxygen surrounding the diffusion pathways appears to be essential in assisting the Li+ mobility in both crystalline and amorphous structures.

Supercapacitor is a newly-developed device for electrochemical energy storage with high power density, long life span, as well as rapid capture and storage of energy. Carbon-based materials, from carbon nanospheres, nanotubes and nanofibers to graphene, are the most commonly used electrode materials for supercapacitors. Our group has engaged in the research of carbon nanomaterials over the past decade. Herein we summarize some typical carbon nanomaterials and their synthetic routes based on our published works, which is expected to provide the theoretical and experimental basis for further applications on carbon-based energy storage devices.

The mechanical properties of as-sintered and heat-exposed polycrystalline Mg2Si were investigated. The strength of the as-fabricated specimen depends on the surface flaws. After heat exposure in Ar atmosphere, oxidized products formed, mainly consisting of MgO. The strength increased after the heat exposure, and the surface oxidation product filled the surface cracks. After the surface oxidation products were removed, the strength and TE properties were the same as those of the as-fabricated specimens.

Carbon based materials have long been investigated as anodes for lithium ion batteries. Among these materials, porous carbon holds several advantages such as high stability, high specific surface area, and excellent cycling capability. To further enhance the energy storage performance, ceramic nanomaterials have been combined with carbon based materials as hybrid anodes for enhanced specific capacity. The use of metal oxide ceramic nanomaterials could enhance the surface electrochemical reactivity thus leads to the increasing of capacity retention at higher number of cycles. In this research, we synthesized ceria (CeO2) nano-particles on porous carbon to form inorganic-organic hybrid composites as an anode material for Li-ion battery. The high redox potential of ceria is expected to increase the specific capacity and energy density of the system. The electrochemical performance was determined by a battery analyzer. It is observed that the specific capacity could be improved by 77% using hybrid composites anode. The material morphology, crystal structure, and thermal stability were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), and Thermogravimetric Analysis (TGA).

An in-depth look at diffusion mechanics within lithium-ion electrodes under fast charging conditions is presented. Electrochemical impedance spectroscopy is used as the primary technique to investigate lithium diffusion within electrode material and in electrolyte near the electrode-electrolyte interface. Half-cells of silicon are charged under varying galvanostatic rates while obtaining impedance data. Collected data is analyzed with the help of an electrical equivalent circuit model that provides mechanical and electrochemical parameters for each instance. The novelty of this equivalent circuit partly lies in its ability to resolve between solid-phase diffusion and liquid-phase diffusion, both of which occur during cycling of a lithium-ion electrode. Observed patterns in the parameters of this circuit provide insight into impact of fast charging on mechanics of lithium diffusion, both inside the electrode matrix and within electrolyte.

La2Hf2O7 and La2Mo2O9 as potential electrolytes for solid oxide fuel cells (SOFCs) have been investigated through first-principles calculations to understand the mechanism of ion motion. In La2Hf2O7, three unique types of positions that can form anion-Frenkel (a-Fr) pairs have been screened out and a reasonable continuous diffusion path constructed by these migration sites has also been suggested as the dominant cause of ion conduction. On the other side, excellent ion conductivity in La2Mo2O9 is more based on the short-range disorder induced by mobile structure. The thermodynamic properties comparison of La2Mo2O9 and La2Hf2O7 shows that the formation of a-Fr pairs in La2Mo2O9 will start at lower temperature because of higher degree of structural disorder and less constraints on oxygen ions.

Herein, silicon nanoparticles (SiNPs) are coated with conducting hydrogel and wrapped with reduced graphene oxide (rGO) sheets via a facile and scalable solution-based sol-gel process. The in-situ polymerized polypyrrole (PPy) hydrogel forms an interconnected three-dimensional (3D) fiber matrix. Amine and hydroxyl groups from the hydrogel assist the encapsulation of the SiNPs through hydrogen bonding. The electro-conductive PPy fiber network and the wrapping of rGO offer efficient electron and ion transport pathways. The PPy/SiNPs/rGO electrodes can produce highly reversible capacities of 1312, 1285 and 1066 mAh g-1 at 100, 250 and 500 cycles at a current density of 2.1 A g-1, respectively.

To better understand the condition of commercial batteries used in Tesla EVs and stationary applications under real performing situations, this article focuses on tracking the temperature of commercial batteries during varying cycling conditions. We have found evidence of significant impact of cycling methods on batteries in ionic conductivity, inner impedance development, and structural change in both cathode and anode electrodes, which will be further analyzed by electrochemical impedance spectroscopy technique in the following research.

The electrophysical (donor-acceptor) properties of the of glass carbon (GC) surface before and after its electrochemical modification in conditions of chemisorption of fluorine-containing nanogroups were studied using the methods of scanning probe microscopy. The values of the coefficients characterizing local (for atomic-scale) electrophysical properties of the surface are calculated on the basis of obtained local spectral dependences of the tunneling current on the tunnelling voltage. Fluorination of the GC surface resulted in change of the ratio of its donor-acceptor atomic characteristics, acceleration of electrode processes, and increase of the overall tunneling activity of local places.