Results 1 - 10 of 47
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[en] Highlights: • A novel multi-model probability battery SoE fusion estimation approach was proposed. • The linear matrix inequality-based H∞ technique is employed to estimate the SoE. • Performance of the method was verified by different batteries at various temperatures. • The results show that the proposed method can achieve accurate SoE estimation. - Abstract: State-of-energy (SoE) is an important index for batteries in electric vehicles and it provides the essential basis of energy application, load equilibrium and security of electricity. To improve the estimation accuracy and reliability of SoE, a novel multi-model fusion estimation approach is proposed against uncertain dynamic load and different temperatures. The main contributions of this work can be summarized as follows: (1) Through analyzing the impact on the estimation accuracy of SoE due to the complexity of models, the necessity of redundant modeling is elaborated. (2) Three equivalent circuit models are selected and their parameters are identified by genetic algorithm offline. Linear matrix inequality (LMI) based H-infinity state observer technique is applied to estimate SoEs on aforementioned models. (3) The concept of fusion estimation is introduced. The estimation results derived by different models are merged under certain weights which are determined by Bayes theorem. (4) Batteries are tested with dynamic load cycles under different temperatures to validate the effectiveness of this method. The results indicate the estimation accuracy and reliability on SoE are elevated after fusion.
[en] As auto manufacturers bring vehicles to market with large batteries that provide over 200 miles of driving range, interest in faster charging options for plug-in electric vehicles (PEVs) is intensifying. This report focuses on direct current fast charger (DCFC) systems and how they can be deployed to provide convenient charging for PEV drivers. First, lessons learned from previous DCFC deployment and data collection activities are shared to describe consumer experience with DCFC systems to date. Second, considerations and criteria are established for designing and upgrading DCFC complexes that provide fast-charging opportunities for PEV drivers in urban communities and on rural corridors. Third, cost estimates are shared for hypothetical high-power DCFC complexes that meet simplified design requirements. Finally, results for a business case analysis are presented that shed light on the financial challenges associated with DCFCs.
[en] To ensure energy security and tackle the intrinsic limitation of 'intermittent availability' of renewable energy sources, two storage technologies, which have become an integral part of energy landscape are: Li-batteries and supercapacitors. The former delivers high energy for long time, while the later delivers appreciable power over a short time period. Supercapacitors are also considered as viable shield to save the expensive Li-batteries from transients or shocks associated with sudden change in demand or supply. With the growing understanding pertaining to the materials used in these technologies, the recent trends indicate industrial need for an energy storage device, which simultaneously has characteristics of both batteries and supercapacitors. Such hybrid storage devices have been termed as 'superbats'. The synthesis protocol for obtaining simple oxides of Fe, Ni, Co, Cu and Mn with morphologies ranging from solid to hollow has been established
[en] Highlights: • Conventional equivalent circuits have been derived from electrical terminal quantities. • Anodic electron flow and electric charge storage were not well modeled electrically. • Novel equivalent-circuit-based model and straightforward test methods are developed. - Abstract: To describe the anodic electron flow and electric charge storage behavior of an MFC system from an electrical perspective, a dynamic model based on a novel electrical equivalent circuit is developed. Conventional equivalent circuits typically have series impedances to model the system from the standpoint of terminal quantities: output voltage and current. However, the conventional approaches do not properly explain internal anodic electron flow and double-layer charge storage characteristics of MFCs. The proposed model uses an equivalent capacitance in parallel and series resistances to accurately model and characterize the anodic electron flow, electrical charge storage, and the dynamic characteristics of both output voltage and current. Two straightforward test methods are proposed to determine the equivalent circuit parameters. Experimental results showed the validity of proposed MFC model.
[en] Highlights: • A single energy storage can always be split into two hybrid energy storages. • These hybrid storages have the same total energy and power as the single storage. • The potential for storage hybridisation depends on the shape of the power profile. • A higher potential allows a higher spread of the power/energy-ratios of the storages. • Automobile and pulsed power applications are well suited for storage hybridisation. - Abstract: Aim of a storage hybridisation is a beneficial usage or combination of different storage technologies with various characteristics to downsize the overall system, decrease the costs or to increase the lifetime, system efficiency or performance. In this paper, the point of interest is a different ratio of power to energy (specific power) of two storages to create a hybrid energy storage system (HESS) with a resulting specific power that better matches the requirements of the application. The approach enables a downsizing of the overall system compared to a single storage system and consequently decreases costs. The paper presents a theoretical and analytical benchmark calculation that determines the maximum achievable hybridisation, i.e. possible spread in specific power, while retaining the original total energy and power capacities of an equivalent single storage system. The theory is independent from technology, topology, control strategy, and application and provides a unified view on hybrid energy storage systems. It serves as a pre-dimensioning tool and first step within a larger design process. Furthermore, it presents a general approach to choose storage combinations and to characterize the potential of an application for hybridisation. In this context, a Hybridisation Diagram is proposed and integral Hybridisation Parameters are introduced.
[en] Highlights: • Advances on layered LiNixCoyMn1−x−yO2 (x ≥ 0.5) positive electrode materials. • Detailed discussion on the preparation, microstructure, modification, etc. • Structure stability, interface compatibility of the positive electrode materials. • The challenges and prospects of nickel-rich layered oxide materials. - Abstract: High energy density lithium-ion batteries are eagerly required to electric vehicles more competitive. In a variety of circumstances closely associated with the energy density of the battery, positive electrode material is known as a crucial one to be tackled. Among all kinds of materials for lithium-ion batteries, nickel-rich layered oxides have the merit of high specific capacity compared to LiCoO2, LiMn2O4 and LiFePO4. They have already become one of the most attractive candidates for the mainstream batteries in industries. In this work, the recent advances on three commonly concerned nickel-rich layered oxides are presented. The preparation, microstructure, electrochemical performances are focused, the modification including coating design as well as dopant selection is specially discussed in details, which is essential to enhance the durability and energy density of lithium-ion batteries. Additionally, the prospects and challenges are also systematically discussed, as well as the potential applications in the field of energy storage technologies.
[en] Sodium (Na)-ion batteries (NIBs) are considered promising alternative candidates to the well-commercialized lithium-ion batteries, especially for applications in large-scale energy storage systems. The electrochemical performance of NIBs such as the cyclability, rate capability, and voltage profiles are strongly dependent on the structural and morphological evolution, phase transformation, sodium-ion diffusion, and electrode/electrolyte interface reconstruction during charge–discharge cycling. Therefore, in-depth understanding of the structure and kinetics of electrode materials and the electrode/electrolyte interfaces is essential for optimizing current NIB systems and exploring new materials for NIBs. Recently, rapid progress and development in spectroscopic, microscopic, and scattering techniques have provided extensive insight into the nature of structural evolution, morphological changes of electrode materials, and electrode/electrolyte interface in NIBs. Here in this review, a comprehensive overview of both static (ex situ) and real-time (in situ or in operando) techniques for studying the NIBs is provided. Lastly, special focus is placed on how these techniques are applied to the fundamental investigation of NIB systems and what important results are obtained.
[en] PIn/MoS2 composite prepared via in-situ oxidative polymerization of indole monomer in the presence of exfoliated MoS2 sheets shows fair capacitive performance. The specific capacitance reaches a value of 173 F g-1 at the current density of 1 A g-1. The close integration of PIn and MOS2 generating interfaces involving two different materials leads to enhanced charge storage properties in the composite. The composite stores charge in bulk mainly through pseudocapacitive mechanism along with some surface storage. The presence of micro and mesopores enhances the surface area and also facilitates the easy charge transport through the electrode material. The composite also shows excellent cyclic stability due to the presence of stable MoS2. (author)
[en] Energy storage must play a crucial role in the widespread adoption of renewable energy sources because they are intermittent. In addition, energy storage is also important in matching the electrical power load with the generation capacity to improve the overall power plant efficiency. This point has been recognized in the recent California state mandate for the electrical utility companies to have energy storage at each power plant in order to utilize their generation capacity more efficiently. While electrochemical energy storage is still very expensive, thermal energy storage can be cost effective even at the present commercial development level, especially for solar CSP plants and conventional thermal power plants. Use of phase change materials for thermal energy storage can increase the storage density, reduce the size and therefore reduce the costs even further. However, it presents certain challenges in terms of poor heat transfer and material compatibility issues. This presentation will describe how these challenges have been overcome by innovative and transformative solutions to develop thermal energy storage using phase change materials at a system cost of less than $15/kWhth as compared to the present commercial thermal energy costs of more than $30/kWhth. (author)