With each passing year, portable electronic devices such as smartphones and laptops have required increasingly efficient energy storage systems in order to ensure satisfactory performance. Nickel hydroxide, in turn, has been extensively studied and used as an electrode material, where improvements in its electrochemical properties end up becoming a major key point for the construction and development of batteries or supercapacitors that have greater charging efficiency, in addition to low cost and long-life cycle. Thus, in this work, a double lamellar hydroxide containing 90% nickel and 10% aluminum (NiAl-LDH-90:10) was synthesized, characterized and its electrochemical behavior was evaluated. Due to the presence of the diffraction peak (003) located in regions of low angle 2θ, the alpha polymorphic phase was attributed to pure nickel hydroxide (Ni100). The nickel and aluminum LDH nanoparticles, obtained by the modified Tower method, showed manometric dimensions in the order of ~5 nm, confirmed by the TEM technique. Through

Lead-free relaxor ferroelectrics are promising materials for energy storage applications. To find new material systems for electrostatic capacitors, many researches have dedicated their work to formulate new ecologically safe compositions. In our study, we have prepared (1−x)Ba(Ti0.93Sn0.07)O3−xBiYO3 (BTS7-BY) solid solutions via the solid-state method. The parent composition, Ba(Ti0.93Sn0.07)O3 is a ferroelectric-relaxor crossover material. It reduces its remanent polarization while still maintaining a high maximum polarization. Moderate substitution with BiYO3 further lowers the remanent polarization, resulting in slimmer polarization loops and increasing the energy storage efficiency to 90 %. Samples with x ≥ 0.06 show a true relaxor behavior with linear-like polarization loops with character of weakly-coupled relaxors. Breakdown strength measurements reveal a reduced breakdown strength with increasing BY content. Further investigations of the electrostriction, the band gap, and the electrical microstructure link the homogeneity and grain size of the microstructure to the resulting breakdown strength. This highlights the importance of a homogenous and small-grained microstructure for enhancing the energy storage properties. Samples with x = 0.06 exhibit the best energy storage properties with a recoverable energy density of 1.11 J/cm3 at 189 kV/cm with an energy storage efficiency of 74%.

Lead-free Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) bulk ceramics have recently gained attention as one of the attractive candidates for electrocaloric cooling due to their large heat absorption capacity induced by electro-structural phase transition near room temperature. However, adiabatic temperature change (ΔT) at room temperature in ceramics has been limited by their relatively low dielectric breakdown strength. Thick films, in this respect, possess the advantages of ceramics (volume) and thin films (thickness). In this work, a systematic ferroelectric and electrocaloric investigation of BCZT thick films, fabricated by electrophoretic deposition combined with laser annealing, has been carried out. Laser annealing at an optimized energy density of 398 W/cm2 has resulted in densely packed grain morphology with no compositional heterogeneities. Analysis of the scaling behavior of dynamic hysteresis revealed that ferroelectric domain reversal in BCZT/Pt has good stability and low energy consumption in the saturation region. The present thick films exhibited larger breakdown strength of 294 kV/cm and recoverable energy storage density of ~7.3 J/cm3 , at least five-fold enhancement compared to the bulk which is stable up to a 4 mm bending radius. The indirect electrocaloric measurements displayed parameters such as a ΔT and entropy change (ΔS) of 2.94 K and 3.1 J kg− 1 K− 1 respectively, for 205 kV/cm which are more than two orders increased compared to the bulk. Higher values of ΔT (1.9 K) at 25 ◦C, refrigerant capacity of 249 J/kg, and responsivity of 0.143 K mm/kV for BCZT/Pt film compared to relevant lead-free ferroelectric thick films elucidate the potential use of these films for solid-state refrigeration applications. The work also presents electrophoretic deposition with laser annealing as an alternative technique to widely studied tape-casting of thick films for electrocaloric studies.

Energy storage systems can make a big difference to reduce both the cost and the impact of fossil fuel's consumption, by either shifting the charging time to off peak-load of demand or being coupled and store energy from green alternatives to energy capture methods. This work presents a shape parametric study on a home heating solution that resorts to a shell and tube heat exchanger system with Phase Change Materials as the Thermal Energy Storage method. A theoretical explanation of its energy storage principles is presented, followed by a state of the arts description of the current applications of this technology in household construction features. A model is then developed based on a researched solution with lauric acid and the efficiency enhancement of its application is performed using Ansys Fluent®. Its calibration and validation is consummated against the results of the already exiting article. The impact of the shape of the heat transfer surface in the convection flows is adressed resorting to parametric studies of 4 cases with their respective horizontal reach incrementally higher. Results revealed that for each 5 mm increase in the heat transfer surface horizontal axis, an average of a 9% decrease in the PCM charging time, resultant of a 5% increase in the melting rate of the material. The higher perimeter for each 5 mm increment also provides a considerable boost of 20% in the peak value of heat transfer rate, as well as a 7% charging time saved to reach the induced convection velocity roof values. The most optimized study of the proposed cases presented a charging time 38% faster than the original.

The decarbonization of the Portuguese electricity system, currently around 50% renewable-based, is undergoing with the commitment to reach 60% of renewable electricity share by 2020. Because of this, the phase-out of the two remaining coal-fired power plants has been receiving close attention, as they currently contribute to about one-fifth of the total electricity generation and two-thirds of the CO2 emissions in the power sector. This work assesses the impact of eliminating coal-fired generation from the Portuguese electricity system without replacing it, and explores a cleaner supply alternative achievable before 2025. Coal phase-out without substitution results in slightly increased CO2 emissions for the atmosphere if one assumes that the required additional imports are of carbon-intensive electricity, leading to the need of adding clean power capacity to the system. It is shown that coal plants could be replaced by about 8 GW of photovoltaics if accompanied by a modest increase in the already existing hydro pump capacity. In this case, the renewable electricity share increases to 77%, and carbon footprint decreases by 56%

Piezoelectric, ferroelectric and electromechanical properties were studied at macroscopic and local scale level in stannum doped (Ba0.88Ca0.12)(SnxZr0.1-xTi0.9)O3 ceramics, with an objective to explore the effect of low content (0  x  0.5 at%) of the substituent (Sn) on the functional properties. The results exemplified that the substitution had an influence on the crystal lattice and microstructure that affected the dielectric, ferroelectric, and electromechanical properties. Enhancement in electrical/electromechanical properties were observed with stannum substitution. Optimal electrical properties were obtained in the composition with Sn = 0.3 at% that exhibited maximum piezoelectric constant d33 = 405 pC/N, planar electromechanical coupling factor kp ~ 0.41, and saturation polarization Ps =12.1 μC/cm2 . The same composition showed an electric-field strain response, Smax ~ 0.08% and a converse piezoelectric coefficient, 33 ∗ of ~ 525 pm/V. Local scale characterization via piezoresponse force microscopy technique revealed complex domain patterns comprising stripe-like macro-domains and featureless nanosized domains. Energy harvesting and energy storage performance were evaluated for exploring their suitability in energy applications

Today the energy sector is still the main contributor towards global warming, raising the urgency for a faster transition from fossil fuels to cleaner energy sources. Due to the renewable’s intermittent availability problem, there is an increased need for better, safer, and more sustainable energy storage solutions. This work focuses on the use of covalent organic frameworks, a type of organic polymers, as electrode materials for lithium-ion batteries. First, the focus was on the synthesis and characterization of redox-active COFs, as well as the design of new COFs with expected increased conductivity. Afterward, the synthesized materials were used as electrodes in coin-cell type lithium batteries. For that purpose, the electrode preparation process was optimized, and the batteries were manufactured and tested. Thus, uncovering relations between covalent organic frameworks and their application as electrode materials for energy storage devices.

The thermodynamics associated with compressed air energy storage is discussed. A systematic methodology for technology analysis, according to compression and reservoir characteristics, is proposed. The technologies and prototypes presented in the literature are organized accordingly, and the potential energy/power densities, and heat losses calculated. The first sensitivity analysis of hydro-pneumatic levelized cost of electricity storage for a set of twelve power system applications, ranging from primary response to seasonal storage is done, using as parameters the specific power and energy investment costs and round-trip efficiency. The electric-to-electric round-trip efficiency for hydro-pneumatic energy storage systems is discussed, using a lab-scale hydro-pneumatic energy storage system that was built using commercially available bladder hydraulic accumulators. In general, the results show that hydro-pneumatic energy storage can be very competitive whenever the number of annual cycles is sufficiently high, as happens in the case of primary response application but, even for applications with a low number of annual cycles, it can be competitive for applications with a high ratio power/capacity. A comparison with the dominant technologies, pumped hydro and Li-Ion, shows that, for the highest hydro-pneumatic energy storage investment costs considered, this technology will only be competitive for primary response, but, for the lowest investment costs considered, hydro-pneumatic energy storage is more cost-effective than Li-Ion for all applications, and can even be more cost-effective than pumped hydro in four of the twelve applications. The main challenges to the development of hydro-pneumatic energy storage systems are discussed, and solutions to these challenges are proposed in the form of two submitted patents.

The perception of the associated impacts among possible management schemes introduces a new way to assess energy storage systems. The ability to define a specific management scheme considering the different stakeholder objectives, both technical and economic, will increase the perception of available installation options. This paper presents a multiobjective feasibility assessment methodology using an improved version of the Non-dominated Sorting Genetic Algorithm II, to optimize the placement of electric energy storage units in order to improve the operation of distribution networks. The model is applied to a case study, using lithium-ion battery technology as an example. The results show the influence of different charging/discharging profiles on the choice of the best battery location, as well as the influence that these choices may have on the different network management objectives, e.g. increasing the integration of renewable generation. As an additional outcome, the authors propose a pricing scheme for filling the present regulatory gap regarding the pricing scheme to be applied to energy storage in order to allow the exploitation of viable business models.

tThe objective of this work is to obtain characteristic daily profiles of consumption, wind generationand electricity spot prices, needed to develop assessments of two different options commonly regardedunder the smart grid paradigm: residential demand response, and small scale distributed electric energystorage. The approach consists of applying clustering algorithms to historical data, namely using a hierar-chical method and a self-organizing neural network, in order to obtain clusters of diagrams representingcharacteristic daily diagrams of load, wind generation or electricity price. These diagrams are useful notonly to analyze different scenarios of combined existence, but also to understand their individual relativeimportance. This study enabled also the identification of a probable range of variation around an averageprofile, by defining boundary profiles with the maximum and minimum values of any cluster prototypes.