Modern polypropylene film power capacitors are state of the art for power factor correction and many DC link applications, but their long-term commercial use is limited to temperatures of less than 85°C. The temperature limit is given by the dielectric polypropylene which has a melting point in the range of 140 to 170°C, while glass is much higher. Thus, the temperature limit could potentially be overcome by use of thin, alkali-free glass as dielectric. “Glass capacitors” employing ultra-thin and high purity glass layers are promising devices for high temperature applications in oil, gas, aerospace, hybrid electric vehicles, DC transmission, and pulsed power systems. This includes emerging power electronic systems using silicon carbide switches and diodes.

This work analyzes and compares various glasses with a thickness of less than 50 µm by dielectric spectroscopy and elemental analysis. It is demonstrated that glass is attractive as dielectric for a wide frequency range up to 200°C. It argues that the dielectric losses are currently too great for thin glass to be used within a commercial power capacitor.

While high temperature prototypes already exist, we demonstrate through our analysis that further developments are required to integrate this promising device into commercial systems. It is seen that even trace amounts of alkali materials can have an impact on losses. These losses must be further reduced through fundamental research into polarization/conduction mechanisms of various glass components.

Quinone/hydroquinone redox couple has been utilized as a source of additional capacitance in typical capacitive energy-storage materials. By generation of functional groups on the carbon electrode surface (grafting) directly from electrolyte there is a possibility to enhance the capacitance value significantly. Hydroxybenzene solutions with different substitution of hydroxyl groups were effectively used for this target. Electrochemical and physicochemical properties of activated carbons have been investigated before and after grafting process.

The solid state electrolyte (SSE) of Li5La3Nb2O12 (LLNO) was synthesized via a novel molten salt synthesis (MSS) method at the relatively low temperature of 900°C. The low sintering temperature prevented the loss of lithium that commonly occurs during synthesis of the SSE using conventional solid state or wet chemical reactions. Recent publications have demonstrated that preserving the Li content is critical in improving the ionic conductivity of SSEs. The LLNO in this experiment showed a high Li-ion conductivity which is comparable to other values reported for LLNO. X-ray diffraction (XRD) measurements confirmed the formation of the cubic garnet Ia-3d crystal structure. In addition, the morphology was examined by scanning electron microscopy (SEM), which showed a uniform grain size and crack-free microstructure. These results demonstrate that MSS is a powerful synthesis method to fabricate LLNO at a relatively low temperature while still achieving a high quality material.

Self-powered microsystems as an alternative to standard systems powered by electrochemical batteries are taking a growing interest. In this work, we propose a different method to store the energy harvested from the ambient which is performed in the mechanical domain. Our mechanical storage concept is based on a spring which is loaded by the force associated to the energy source to be harvested [1]. The approach is based on pressing an array of fine wires (fws) grown vertically on a substrate surface. For the fine wires based battery, we have chosen ZnO fine wires due the fact that they could be grown using a simple and cheap process named hydrothermal method [2]. We have reported previous experiments changing temperature and initial pH of the solution in order to determine the best growth [3]. From new experiments done varying the compounds concentration the best results of fine wires were obtained. To characterize these fine wires we have considered that the maximum load we can apply to the system is limited by the linear buckling of the fine wires. From the best results we obtained a critical strain of εc = 3.72 % and a strain energy density of U = 11.26 MJ/m3, for a pinned-fixed configuration [4].

Li attachment to free tetracyanoethylene (TCNE) molecules and TCNE adsorbed on doped graphene is studied using density functional theory. While TCNE is adsorbed only weakly on ideal graphene, we identified a configuration in which TCNE is chemisorbed on Al-doped graphene via its C atom and a surface oxygen atom. Up to four Li atoms can be stored on both free and adsorbed TCNE with binding energies stronger than cohesive energy of the Li metal. TCNE immobilized on the conducting graphene-based substrate could therefore become an efficient anode material for organic Li ion batteries.