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Su A.D.,National University of Singapore | Zhang X.,National University of Singapore | Rinaldi A.,TUM CREATE Ltd. | Nguyen S.T.,National University of Singapore | And 4 more authors.
Chemical Physics Letters | Year: 2013

Hierarchical porous carbon anode and metal oxide cathode are promising for supercapacitor with both high energy density and high power density. This Letter uses NiO and commercial carbon nanotubes (CNTs) as electrode materials for electrochemical capacitors with high energy storage capacities. Experimental results show that the specific capacitance of the electrode materials for 10%, 30% and 50% CNTs are 279, 242 and 112 F/g, respectively in an aqueous 1 M KOH electrolyte at a charge rate of 0.56 A/g. The maximum specific capacitance is 328 F/g at a charge rate of 0.33 A/g. © 2013 Elsevier B.V. All rights reserved. Source

Rieger B.,TU Munich | Schlueter S.,TUM CREATE Ltd. | Erhard S.V.,TU Munich | Jossen A.,TU Munich
Journal of the Electrochemical Society | Year: 2016

The propagation of strain within a commercial LiCoO2 (LCO) electrode for lithium-ion batteries is investigated during cycling. An experimental multiscale approach is combined with microstructural, mechanical simulations. The crystal structure exhibits a volume change of 2.32% measured by in operando X-ray diffraction (XRD) measurements. The resulting change in the electrode thickness is about 1.8% and is measured by electrochemical dilatometry. The width of the electrode, volume fraction of active material, and binder geometry all affect the electrode deformation; this is investigated using a representative spherical particle model (RSPM). Thereby, the anisotropic swelling behavior of the electrode is verified, as the in-plane expansion of the electrode is restricted by interactions between the particles, binder, and the current collector. SEM images of the electrode are used to model the electrode expansion in a realistic microstructure. The simulation reveals that load paths form inside the electrode and cause stress peaks inside the binder material. To compare the 2D simulations with experimental data, a 3D RSPM is constructed. Based on these findings, we propose an equation that predicts the expansion of electrodes based on characteristics of the crystal structure. © 2016 The Electrochemical Society. All rights reserved. Source

Nguyen S.T.,National University of Singapore | Nguyen H.T.,Nanyang Technological University | Rinaldi A.,TUM CREATE Ltd. | Nguyen N.P.V.,National University of Singapore | And 2 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2012

Of all the challenges facing human beings in the near future, energy related issues are likely to be the grandest. To achieve a more sustainable society with adequate renewable energy and less environmental pollution, more versatile, robust and efficient approaches in electric energy storage and conversion are needed. To achieve these goals, the development of new electrode materials with high electrical conductivity, corrosion-resistance, high specific surface area, high porosity and low cost is highly desirable. Graphene aerogels (GAs) have been focused recently due to novel properties of graphene (extremely low electrical and thermal resistivity, large carrier mobility, high surface area and mechanical elasticity) and the low cost and easy preparation of graphene from graphite. The performance of GA-based electrodes strongly depends on the morphology and structure of the GAs. However, there has been little study on the optimization of the GA nanostructures in terms of surface area, pore size, pore volume and density for energy storage devices. In this work, the GA nanostructures synthesized from commercial graphite were controlled successfully. The graphene oxide (GO) was prepared from commercial graphite powder using a modified Hummers method. A hydrothermal method was used to synthesize GAs due to its simplicity, environmental friendliness and low cost. No binders were used to prevent their negative effects to the electrical conductivity of the aerogels. Effects of fabrication conditions and the GO concentration on the GA nanostructures were also quantified. A maximum Brunauer-Emmett-Teller (BET) surface area of 394m 2/g and the lightest density of 0.042g/cm 3 were achieved when the GA with 3mgGO/mL was hydrothermally treated at 180°C for 1.5h. The thermal durability analysis showed that the GAs could be stable up to 500°C in air, with 24h of hydrothermal treatment time. Preliminarily the GA hydrothermally treated for 6h had an electrical conductivity of 0.004S/cm. The experimental results of the study are useful for optimizing GA structures for energy storage applications. © 2012. Source

Siala K.,TU Munich | Stich J.,TUM CREATE Ltd.
Renewable Energy | Year: 2016

Further exploitation of renewable energy sources for power generation could mitigate the current rapid increase of greenhouse gas emissions in South East Asia. In this context, solar PV is a promising option as PV system costs have been declining continuously over the past. In order to define strategies towards a low-carbon future power supply, detailed information on the potential power output of solar PV is essential.Therefore, this paper analyses the resource and technical potential of solar PV in South East Asia in high temporal and spatial resolution. An empirical, climate-based Ångström-Prescott model is proposed in order to adjust MERRA solar radiation data. The possible power output of PV is derived considering topographic and land-use constraints as well as technological characteristics of typical PV systems.Java, central Myanmar and eastern Thailand were identified to be the best locations for PV use, with capacity factors exceeding 15%. Due to the large land area which is suitable for PV installations, South East Asia offers an abundant theoretical potential of solar PV, amounting to 430 TW h with conservative assumptions. © 2015 Elsevier Ltd. Source

TUM CREATE Ltd | Date: 2015-08-18

A vehicle seat with integrated child seat comprising: a passenger seat backrest and a seat cushion configured to seat a front-facing adult, the passenger seat backrest further configured to be foldable onto the seat cushion; a child seat backrest integrated with the passenger seat backrest, the child seat backrest configured to be raisable from the passenger seat backrest when the passenger seat backrest is folded onto the seat cushion so as to form a rear-facing child seat.

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