Composites For Energy Storage Applications Research Articles

Recent Advances in 3D Graphene Architectures and Their Composites for Energy Storage Applications.

Graphene is widely applied as an electrode material in energy storage fields. However, the strong π-π interaction between graphene layers and the stacking issues lead to a great loss of electrochemically active surface area, damaging the performance of graphene electrodes. Developing 3D graphene architectures that are constructed of graphene sheet subunits is an effective strategy to solve this problem. The graphene architectures can be directly utilized as binder-free electrodes for energy storage devices. Furthermore, they can be used as a matrix to support active materials and further improve their electrochemical performance. Here, recent advances in synthesizing 3D graphene architectures and their composites as well as their application in different energy storage devices, including various battery systems and supercapacitors are reviewed. In addition, their challenges for application at the current stage are discussed and future development prospects are indicated.

Carbon nanofibers wrapped with zinc oxide nano-flakes as promising electrode material for supercapacitors

A combination of electrospinning technique and hydrothermal process was carried out to fabricate zinc oxide nano-flakes wrapped carbon nanofibers (ZnO/CNFs) composite as an effective electrode material for supercapacitor. The morphology of the as-synthesized composite clearly revealed that the carbon nanofibers were successfully wrapped with ZnO nano-flakes. The electrochemical performance of the as-synthesized nanocomposite electrode was evaluated by the cyclic voltammetry (CV), galvanostatic charge–discharge (GDC), and electrochemical impedance spectroscopy (EIS), and compared with the pristine ZnO nanofibers. It was found that the composite exhibited a higher specific capacitance (260 F/g) as compared to pristine ZnO NFs (118 F/g) at the scan rate of 5 mV/s. Furthermore, the ZnO/CNFs composite also exhibited good capacity retention (73.33%). The obtained results indicated great potential applications of ZnO/CNFs composite in developing energy storage devices with high energy and power densities. The present work might provide a new route for utilizing ZnO based composites for energy storage applications.

Physico-chemical properties of Bismuth nitrate filled PVA–LiClO4 polymer composites for energy storage applications

A series of polymer composites were prepared by the addition of Bismuth nitrate (Bi(NO3)3) and Lithium perchlorate (LiClO4) to poly(vinyl alcohol) (PVA) polymer matrix by solvent casting method. The microstructures and surface morphology were systematically characterized by FTIR spectroscopy, X-ray diffraction, AFM and SEM analysis. The DSC thermal studies exhibit the transformations in the composites due to the effect of Bi(NO3)3. The mechanical strength, ac and dc conducting properties were studied. The variation of ac conductivity of the composites with frequency follows Jonscher’s universal power law and found to be increased with increasing temperature. The sample containing 10 wt% Bi(NO3)3 exhibits good mechanical strength, high conductivity and dielectric constant at room temperature. The variation of conducting properties of 10 wt% Bi(NO3)3 filled composite with temperature has been explained based on hopping mechanism. The frequency exponent (s) have been well fitted with the proposed correlation equation of the barrier hopping model. The transport parameters are estimated using Rice and Roth model. The activation energy is calculated for the sample PVA–LiClO4 matrix filled with 10 wt% Bi(NO3)3 using Arrhenius equation.

Flexible and low cost lead free composites with high dielectric constant

Highly flexible lead free composite film having random distribution of ceramic filler was synthesized using Barium Titanate (BT) as a filler and inexpensive Thermoplastic Polyurethane (TPU) as a matrix. The results show that the 30vol% BT-TPU composite has a dielectric constant of ~31 which is comparable to the expensive and difficult to produce PVDF based composites. With a breakdown field of 150kV/mm, an energy density value of ~3J/cm3 was estimated. These lead-free TPU based composites provide an alternative to PVDF based composites for energy storage applications.

Nanostructured MoS2/BiVO4 Composites for Energy Storage Applications.

We report the optimized synthesis and electrochemical characterization of a composite of few-layered nanostructured MoS2 along with an electroactive metal oxide BiVO4. In comparison to pristine BiVO4, and a composite of graphene/BiVO4, the MoS2/BiVO4 nanocomposite provides impressive values of charge storage with longer discharge times and improved cycling stability. Specific capacitance values of 610 Fg−1 (170 mAhg−1) at 1 Ag−1 and 166 Fg−1 (46 mAhg−1) at 10 Ag−1 were obtained for just 2.5 wt% MoS2 loaded BiVO4. The results suggest that the explicitly synthesized small lateral-dimensioned MoS2 particles provide a notable capacitive component that helps augment the specific capacitance. We discuss the optimized synthesis of monoclinic BiVO4, and few-layered nanostructured MoS2. We report the discharge capacities and cycling performance of the MoS2/BiVO4 nanocomposite using an aqueous electrolyte. The data obtained shows the MoS2/BiVO4 nanocomposite to be a promising candidate for supercapacitor energy storage applications.

Role of ZrO2 on physico‐chemical properties of PVA/NaClO4 composites for energy storage applications

A novel polymer nano composite electrolyte composed of PVA polymer matrix with ZrO2 ceramic filler and NaClO4 salt was prepared by a solution casting. The characteristic properties of PVA/NaClO4 polymer composite electrolytes with ZrO2 filler were studied using FTIR, X‐ray diffractometer (XRD), FESEM, DSC, AFM, AC impedance method, and cyclic voltammeter. The sample containing 3 wt% ZrO2 exhibits good mechanical strength, high conductivity, high dielectric constant and good electrochemical response at room temperature. The conduction mechanism of the composite can be represented by the correlated barrier hopping (CBH) model and the obtained frequency dependent S parameter obeys Almond—West Universal power law. Using Williams–Landel–Ferry (WLF) and Vogel Fulcher Tamman (VTF) equations equivalence correlated the dynamic fragility (m) and activation energy (Eg) with Tg of polymer composites. Transport parameters were calculated using Rice and Roth model. The cyclic voltamograms shows that the prepared films were Pseudo‐capacitive in nature. POLYM. COMPOS., 39:1273–1282, 2018. © 2016 Society of Plastics Engineers

Reverse boundary layer capacitor model in glass/ceramic composites for energy storage applications

Reverse boundary layer capacitor (RBLC) configuration model, where the grain boundary has a higher electrical conductivity than the grain, is proposed in glass/ceramic composites for dielectric energy storage applications. By introducing glass additives as grain boundaries with electrical conductivity higher than ceramic grains, the steady electric field across grains can be larger than grain boundaries as desired due to the conductivity difference. The breakdown field is thus expected to increase in the RBLC-type brick wall model because of the field distribution. The equivalent circuit, grain boundary conductivity dependence of energy density, low-loss frequency range of the RBLC model are discussed. The simulation results suggest that the RBLC approach has advantages in overall energy density, compared with normal insulating glass phase composites.

Development of Lead-Free Nanowire Composites for Energy Storage Applications

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 (NaNbO3) 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 NaNbO3/PVDF composites was also compared with that of lead-containing (PbTiO3/PVDF) nanocomposites and previously developed Pb()O3/PVDF composites to show the feasibility of replacing lead-containing materials. The energy density of NaNbO3/PVDF capacitor is comparable to those of lead-containing ones, indicating the possibility of expelling lead from high-energy density dielectric capacitors.

Nanostructured Composites for Energy Storage Applications

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