Energy Storage

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Browsing Energy Storage by Funder "N/A"

Now showing 1 - 4 of 4
  • Publication
    Publication
    Ab Initio Study of Structural and Vibrational Properties of Fe2P-Type Materials for Near - Room - Temperature Refrigeration
    (Science and Education publishing (SciEP), 2022-01-23) Thirika, Anne Mwende; Mulwa, Winfred Mueni; Makau, Nicholus Wambua; Ibrahim, Adentuji Bamidele
    This work has applied density functional theory (DFT) based calculations to investigate the structural and vibrational properties of FeMnP1−xAx (A= Si, Se, Sn and In, x = 0.33) within the first-principles pseudopotential technique. The exchange correlation potentials were treated within generalized gradient approximation (GGA), in the Quantum ESPRESSO code. The Perdew, Burke, Ernzerhof (PBE) functional as implemented in Vanderbilt's ultra-soft pseudo potential (USPP) was used for all the calculations. Vibrational properties were calculated using phonopy code with 1 × 1 × 2 supercell of the conventional unit cell. Thermodynamic properties were predicted using the phonon density of states. The dependence of lattice thermal conductivity on temperature was determined using Debye theory. The optimized structural parameters and corresponding graphical values fit within available experimental data and other theoretical reports. There were no imaginary phonon modes in the phonon dispersion curves revealing that these materials are dynamically stable for magnetic refrigeration.
  • Publication
    Publication
    Germanium quantum dot/nitrogen-doped graphene nanocomposite for high-performance bulk heterojunction solar cells
    (Royal Society of Chemistry, 2018-06-30) Amollo, Tabitha A.; Mola, Genene T.; Nyamori, Vincent O.
    This study presents the successful synthesis of a novel nanocomposite, namely a germanium quantum dot/nitrogen-doped graphene nanocomposite (GeQD/NGr), and its use in the modification of the photoactive medium of bulk heterojunction solar cells (BHJ-SCs). The nanocomposite was prepared in two sequential steps. Firstly, a reduced graphene oxide-germanium oxide nanocomposite (rGO-GeO2) was synthesized by microwave-assisted solvothermal reaction. The second step involved simultaneous N-doping of graphene and reduction of GeO2 to obtain the GeQD/NGr nanocomposite by thermal treatment. The nanocomposite consists of highly crystalline, spherical shaped GeQDs with a mean diameter of 4.4 nm affixed on the basal planes of NGr sheets. Poly-3-hexylthiophene (P3HT), (6-6)phenyl-C60-butyric acid methyl ester (PCBM) and GeQD/NGr were used as the photoactive layer blend in the fabrication of BHJ-SCs. Enhanced short-circuit current density (Jsc) and fill factor (FF) is derived from the incorporation of the GeQD/NGr nanocomposite in the active layer. The nanocomposite in the active layer blend serves to ensure effective charge separation and transportation to the respective electrodes. Consequently, an improvement of up to 183% in the power conversion efficiency is achieved in the BHJ-SCs by the GeQD/NGr modification.
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    Publication
    Graphene-Based Materials for Energy Conversion
    (Wiley, 2012-05-10) Sahoo, Nanda Gopal; Pan, Yongzheng; Li, Lin; Chan, Siew Hwa
    With the depletion of conventional energy sources, the demand for renewable energy and energy-efficient devices continues to grow. As a novel 2D nanomaterial, graphene attracts considerable research interest due to its unique properties and is a promising material for applications in energy conversion and storage devices. Recently, the fabrication of fuel cells and solar cells using graphene for various functional parts has been studied extensively. This research news summarizes and compares the advancements that have been made and are in progress in the utilization of graphene-based materials for energy conversion.
  • Publication
    Publication
    Safety of Rechargeable Energy Storage Systems with a focus on Li-ion Technology
    (Elsevier Ltd, 2017-02-10) Pfrang, A.; Kriston, A.; Ruiz, V.; Lebedeva, N.; di Persio, F.
    In this chapter the safety of rechargeable energy storage systems is discussed with a focus on Li-ion batteries. The main hazards, such as fire, explosion, direct electrical hazards (electrical shock and arcing), indirect electrical hazards, and chemical hazards are reviewed. Relevant failure scenarios—overheating, mechanical deformation, external short circuit, and overcharge—are presented together with the main approaches for risk mitigation. Potential safety implications of the application of nanomaterials in rechargeable energy storage systems are discussed. Finally, a comprehensive summary of the most common tests for assessing safety under thermal, electrical, and mechanical abusive conditions as described in relevant standards and regulations is given.