Energy-Efficient Smart Home System: Optimization of Residential Electricity Load Management System

In this project, an algorithm for electrical load management in a hypothetical household setting is proposed, developed and simulated. There are two main goals for the algorithm; firstly, to minimize the total electricity cost when a variable pricing model is applied; secondly, to flatten the demand curve over 24 hours, which, when applied to real-life settings, will minimize investment costs for the utilities – including building more generation plants and transmission lines – as well as the total bill for customers. To simulate the algorithm, mathematical models for appliances are developed based on typical usage and operation patterns

Topological Phase Transitions in Line-nodal Superconductors

Fathoming interplay between symmetry and topology of many-electron wave-functions has deepened understanding of quantum many body systems, especially after the discovery of topological insulators. Topology of electron wave-functions enforces and protects emergent gapless excitations, and symmetry is intrinsically tied to the topological protection in a certain class. Namely, unless the symmetry is broken, the topological nature is intact. We show novel interplay phenomena between symmetry and topology in topological phase transitions associated with line-nodal superconductors. The interplay may induce an exotic universality class in sharp contrast to that of the phenomenological Landau-Ginzburg theory. Hyper-scaling violation and emergent relativistic scaling are main characteristics, and the interplay even induces unusually large quantum critical region. We propose characteristic experimental signatures around the phase transitions in three spatial dimensions, for example, a linear phase boundary in a temperature-tuning parameter phase-diagram.Comment: 4 + 23 pages, 7 figures, 1 table; the first two authors contributed equally to this wor

Facile electrodeposition of high-density CuCo2O4 nanosheets as a high-performance Li-ion battery anode material

High-density CuCo2O4 nanosheets are grown on Ni foam using electrodeposition followed by air annealing for a Li-ion battery anode. The anode exhibits a high discharge capacity of 1244 mAh/g at 0.1 A/g (82% coulombic efficiency) and excellent high-rate performance with 95% capacity retention (1100 mAh/g after 200 cycles at 1 A/g). The outstanding battery performance of the CuCo2O4 anode is attributed to its binder-free direct contact to the current collector and high-density nanosheet morphology. The present experimental findings demonstrate that the electrodeposited binder-free CuCo2O4 material may serve as a safe, low-cost, long-cycle life anode for Li-ion batteries

Nanoflake NiMoO4 based smart supercapacitor for intelligent power balance monitoring.

A supercapacitor is well recognized as one of emerging energy sources for powering electronic devices in our daily life. Although various kind of supercapacitors have been designed and demonstrated, their market aspect could become advanced if the utilisation of other physicochemical properties (e.g. optical) is incorporated in the electrode. Herein, we present an electrochromic supercapacitor (smart supercapacitor) based on a nanoflake NiMoO4 thin film which is fabricated using a facile and well-controlled successive ionic layer adsorption and reaction (SILAR) technique. The polycrystalline nanoflake NiMoO4 electrode exhibits a large electrochemically active surface area of ~ 96.3 cm2. Its nanoporous architecture provides an easy pathway for the intercalation and de-intercalation of ions. The nanoflake NiMoO4 electrode is dark-brown in the charged state and becomes transparent in the discharged state with a high optical modulation of 57%. The electrode shows a high specific capacity of 1853 Fg–1 at a current rate of 1 Ag–1 with a good coloration efficiency of 31.44 cm2/C. Dynamic visual information is obtained when the electrode is charged at different potentials, reflecting the level of energy storage in the device. The device retains 65% capacity after 2500 charge-discharge cycles compared with its initial capacity. The excellent performance of the nanoflake NiMoO4 based smart supercapacitor is associated with the synergetic effect of nanoporous morphology with a large electrochemically active surface area and desired chemical composition for redox reaction

Influence of operating temperature on Li2ZnTi3O8 anode performance and high-rate charging activity of Li-ion battery

The temperature-dependent performance of a Li2ZnTi3O8 (LZTO) anode and the ultrafast-charging activity of a Li-ion battery were investigated. The LZTO anode operates at different temperatures between − 5 and 55 °C and in this work its sustainability is discussed in terms of storage performance. It delivered a discharge capacity of 181.3 mA h g−1 at 25 °C, which increased to 227.3 mA h g−1 at 40 °C and 131.2 mA h g−1 at − 5 °C. The variation in the discharge capacity with temperature is associated with the reaction kinetics and the change in internal resistance. It showed a capacity retention of 64% and a coulombic efficiency of 98% over 500 cycles. Exhibiting a discharge capacity of 107 mA h g−1, the LZTO anode was sustainable over 100 charge-discharge cycles at an ultra-high charging rate of 10 Ag−1. The reaction kinetics estimated from a cyclic voltammetry analysis at high scan rates revealed a capacitive-type storage mechanism

Self-assembled nanostructured CuCo2 O4 for electrochemical energy storage and the oxygen evolution reaction via morphology engineering

CuCo2O4 films with different morphologies of either mesoporous nanosheets, cubic, compact‐granular, or agglomerated embossing structures are fabricated via a hydrothermal growth technique using various solvents, and their bifunctional activities, electrochemical energy storage and oxygen evolution reaction (OER) for water splitting catalysis in strong alkaline KOH media, are investigated. It is observed that the solvents play an important role in setting the surface morphology and size of the crystallites by controlling nucleation and growth rate. An optimized mesoporous CuCo2O4 nanosheet electrode shows a high specific capacitance of 1658 F g−1 at 1 A g−1 with excellent restoring capability of ≈99% at 2 A g−1 and superior energy density of 132.64 Wh kg−1 at a power density of 0.72 kW kg−1. The CuCo2O4 electrode also exhibits excellent endurance performance with capacity retention of 90% and coulombic efficiency of ≈99% after 5000 charge/discharge cycles. The best OER activity is obtained from the CuCo2O4 nanosheet sample with the lowest overpotential of ≈290 mV at 20 mA cm−2 and a Tafel slope of 117 mV dec−1. The superior bifunctional electrochemical activity of the mesoporous CuCo2O4 nanosheet is a result of electrochemically favorable 2D morphology, which leads to the formation of a very large electrochemically active surface area

Self-assembled two-dimensional copper oxide nanosheet bundles as an efficient oxygen evolution reaction (OER) electrocatalyst for water splitting applications

A high activity of a two-dimensional (2D) copper oxide (CuO) electrocatalyst for the oxygen evolution reaction (OER) is presented. The CuO electrode self-assembles on a stainless steel substrate via chemical bath deposition at 80 °C in a mixed solution of CuSO4 and NH4OH, followed by air annealing treatment, and shows a 2D nanosheet bundle-type morphology. The OER performance is studied in a 1 M KOH solution. The OER starts to occur at about 1.48 V versus the RHE (η = 250 mV) with a Tafel slope of 59 mV dec−1 in a 1 M KOH solution. The overpotential (η) of 350 mV at 10 mA cm−2 is among the lowest compared with other copper-based materials. The catalyst can deliver a stable current density of >10 mA cm−2 for more than 10 hours. This superior OER activity is due to its adequately exposed OER-favorable 2D morphology and the optimized electronic properties resulting from the thermal treatment

Nanoporous CuCo2O4 nanosheets as a highly efficient bifunctional electrode for supercapacitors and water oxidation catalysis

Efficient and low‐cost multifunctional electrodes play a key role in improving the performance of energy conversion and storage devices. In this study, ultrathin nanoporous CuCo2O4 nanosheets are synthesized on a nickel foam substrate using electrodeposition followed by air annealing. The CuCo2O4 nanosheet electrode exhibits a high specific capacitance of 1473 F g─1 at 1 A g─1 with a capacity retention of ∼93% after 5000 cycles in 3 M KOH solution. It also works well as an efficient oxygen evolution reaction electrocatalyst, demonstrating an overpotential of 260 mV at 20 mA cm─2 with a Tafel slope of ∼64 mV dec─1. in 1 M KOH solution, which is the lowest reported among other copper-cobalt based transition metal oxide catalysts. The catalyst is very stable at >20 mA cm─2 for more than 25 h. The superior electrochemical performance of the CuCo2O4 nanosheet electrode is due to the synergetic effect of the direct growth of 2D nanosheet structure and a large electrochemically active surface area associated with nanopores on the CuCo2O4 nanosheet surface

Nanofilament array embedded tungsten oxide for highly efficient electrochromic supercapacitor electrodes

The high-activity of metallic nanofilament array (NFA) embedded tungsten oxide (WO3) bifunctional electrodes for electrochromism and electrochemical energy storage is presented. The NFA reduces charge transfer resistance and increases the electrochemically active surface area at the electrode–electrolyte interface. The NFA-embedded WO3 electrode exhibits a specific capacity of 214 F g−1 (pristine WO3: 133 F g−1) at 0.25 mA cm−2, excellent cycling stability with ∼92% capacitance retention after 2000 cycles (pristine WO3: ∼75% capacitance retention) and a coloration efficiency of 128 cm2 C−1 (pristine WO3: 91 cm2 C−1) with superb optical modulation. These properties are significantly more advanced compared to the pristine WO3 electrode and superior to previously reported WO3-based composites and nanostructured materials