Lithium-ion batteries (LIB) have been receiving extensive attention because of the high specific energy density for wide applications such as electronic vehicles, commercial mobile electronics, and military applications. In LIB, graphite is the most commonly used anode material; however, lithium-ion intercalation in graphite is limited, hindering the battery charge rate and capacity. To overcome this obstacle, nanostructured anode assembly has been extensively studied to increase the lithium-ion diffusion rate. Among these approaches, high specific surface area metal oxide nanowires connecting nanostructured carbon materials accumulation have shown propitious results for enhanced lithium intercalation. Recently, nanowire/graphene hybrids were developed for the enhancement of LIB performance; however, almost all previous efforts employed nanowires on graphene in a random fashion, which limited lithium-ion diffusion rate. Therefore, we demonstrate a new approach by hydrothermally growing uniform nanowires on graphene aerogel to further improve the performance. This nanowire/graphene aerogel hybrid not only uses the high surface area of the graphene aerogel but also increases the specific surface area for electrode-electrolyte interaction. Therefore, this new nanowire/graphene aerogel hybrid anode material could enhance the specific capacity and charge-discharge rate. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used for materials characterization. Battery analyzer and potentio-galvanostat are used for measuring the electrical performance of the battery. The testing results show that nanowire graphene hybrid anode gives significantly improved performance compared to graphene anode.

There is an increasing demand to improve the energy density of dielectric capacitors for satisfying the next generation material systems. One effective approach is to embed high dielectric constant inclusions such as lead zirconia titanate in polymer matrix. However, with the increasing concerns on environmental safety and biocompatibility, the need to expel lead (Pb) from modern electronics has been receiving more attention. Using high aspect ratio dielectric inclusions such as nanowires could lead to further enhancement of energy density. Therefore, this paper focuses on the development of a lead-free nanowire reinforced polymer matrix capacitor for energy storage application. Lead-free sodium niobate nanowires (NaNbO 3 ) were synthesized using hydrothermal method, followed by mixing them with polyvinylidene fluoride (PVDF) matrix using a solution-casting method for nanocomposites fabrication. Capacitance and breakdown strength of the samples were measured to determine the energy density. The energy density of NaNbO 3 /PVDF composites was also compared with that of lead-containing (PbTiO 3 /PVDF) nanocomposites and previously developed Pb(Zr 0.2 Ti 0.8 )O 3 /PVDF composites to show the feasibility of replacing lead-containing materials. The energy density of NaNbO 3 /PVDF capacitor is comparable to those of lead-containing ones, indicating the possibility of expelling lead from high-energy density dielectric capacitors.

The study of electrochemical super-capacitors has become one of the most attractive topics in both academia and industry as energy storage devices because of their high power density, long life cycles, and high charge/discharge efficiency. Recently, there has been increasing interest in the development of multifunctional structural energy storage devices such as structural super-capacitors for applications in aerospace, automobiles, and portable electronics. These multifunctional structural super-capacitors provide structures combining energy storage and load bearing functionalities, leading to material systems with reduced volume and/or weight. Due to their superior materials properties, carbon fiber composites have been widely used in structural applications for aerospace and automotive industries. Besides, carbon fiber has good electrical conductivity which will provide lower equivalent series resistance; therefore, it can be an excellent candidate for structural energy storage applications. Hence, this paper is focused on performing a pilot study for using nanowire/carbon fiber hybrids as building materials for structural energy storage materials; aiming at enhancing the charge/discharge rate and energy density. This hybrid material combines the high specific surface area of carbon fiber and pseudo-capacitive effect of metal oxide nanowires, which were grown hydrothermally in an aligned fashion on carbon fibers. The aligned nanowire array could provide a higher specific surface area that leads to high electrode-electrolyte contact area thus fast ion diffusion rates. Scanning Electron Microscopy and X-Ray Diffraction measurements are used for the initial characterization of this nanowire/carbon fiber hybrid material system. Electrochemical testing is performed using a potentio-galvanostat. The results show that gold sputtered nanowire carbon fiber hybrid provides 65.9% higher energy density than bare carbon fiber cloth as super-capacitor.

The study of graphene has become one of the most exhilarating topics in both academia and industry for being highly promising in various applications. Because of its excellent mechanical, electrical, thermal and nontoxic properties, graphene has shown promising application in energy storage devices such as lithium-ion-battery (LIB), super capacitor and solar cell. In lithium ion battery, graphite is the most commonly used material as anode. However, due to the limited specific surface area of graphite materials, the diffusion of the Li ions in the anode graphite is relatively slow, leading to limited energy storage density. In order to further increase the capacity, nano-structured materials have been extensively studied due to its potential in reducing Li-ion diffusion pathway. To date, one of the most promising approaches to improve the Li-ion diffusion rate is to introduce hybrid nanostructured electrodes that connect the nonconductive high surface area nanowire with nanostructured carbon materials. While there have been several research efforts investigated to fabricate nanowire-graphene hybrids, all the them were focused on randomly distributed nanostructures thus the LIB performance enhancement was limited. Therefore, this paper will introduce a novel hybrid structure with vertically aligned nanowire on graphene aerogel aiming to further increase the performance of LIB. The aligned nanowire array provides a higher specific surface area and could lead to high electrodeelectrolyte contact area and fast lithium ion diffusion rate. While the graphene aerogel structure is electrically conductive and mechanically robust, as well as has low specific density. The developed nanowire/graphene hybrid structure could have the potential to enhance the specific capacity and charge-discharge rate. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) measurements were used for the initial characterization of this nanowire/graphene aerogel hybrid material system.

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