A review of fractional-order techniques applied to lithium-ion batteries, lead-acid batteries, and supercapacitors

Electrochemical energy storage systems play an important role in diverse applications, such as electrified transportation and integration of renewable energy with the electrical grid. To facilitate model-based management for extracting full system potentials, proper mathematical models are imperative. Due to extra degrees of freedom brought by differentiation derivatives, fractional-order models may be able to better describe the dynamic behaviors of electrochemical systems. This paper provides a critical overview of fractional-order techniques for managing lithium-ion batteries, lead-acid batteries, and supercapacitors. Starting with the basic concepts and technical tools from fractional-order calculus, the modeling principles for these energy systems are presented by identifying disperse dynamic processes and using electrochemical impedance spectroscopy. Available battery/supercapacitor models are comprehensively reviewed, and the advantages of fractional types are discussed. Two case studies demonstrate the accuracy and computational efficiency of fractional-order models. These models offer 15–30% higher accuracy than their integer-order analogues, but have reasonable complexity. Consequently, fractional-order models can be good candidates for the development of advanced b attery/supercapacitor management systems. Finally, the main technical challenges facing electrochemical energy storage system modeling, state estimation, and control in the fractional-order domain, as well as future research directions, are highlighted

Power and energy management of grid/PEMFC/battery/supercapacitor hybrid power sources for UPS applications

© 2014 Elsevier Ltd. All rights reserved. This paper presents a hybrid power and energy source supplied by a proton exchange membrane fuel cell (PEMFC) as the main power source in an uninterruptible power supply (UPS) system. To prevent the PEMFC from fuel starvation and degradation and realize their seamless linking in the hybrid UPS system, the power and energy are balanced by the battery and/or supercapacitor (SC) as two alternative auxiliary power sources. Based on the modeling and sizing of hybrid power and energy components, the power and energy management strategies and efficiency measurements of four operating modes in UPS system are proposed. To evaluate the proposed strategies, an experimental setup is implemented by a data acquisition system, a PEMFC generating system, and a UPS system including AC/DC rectifier, DC/AC inverter, DC/DC converter, AC/DC recharger and its intelligent control unit. Experimental results with the characteristics of a 300 W self-humidified air-breathing of PEMFC, 3-cell 12 V/5 Ah of batteries, and two 16-cell 120 F/2.7 V of SCs in parallel corroborate the excellent management strategies in the four operating modes of UPS system, which provides the basis for the optimal design of the UPS system with hybrid PEMFC/battery/SC power sources

Novel Design And Synthesis Of Transition Metal Hydroxides And Oxides For Energy Storage Device Applications

Supercapacitors (SCs) and Li-ion batteries (LIBs) are two types of important electrical energy storage devices with high power density and high energy density respectively. However, to satisfy the increasing demand of high-performance energy storage devices, the energy density of SCs and power/energy densities of LIBs have to be further improved. The exploration, research, and development of electrode materials with high-performance for applications in SCs and LIBs are still needed to meet the ever-increasing demand on energy and power densities. Herein, the amorphous Ni-Co-Mo ternary hydroxides nanoflakes for SCs and oxides nanoflakes for LIBs with ultrathin stature, abundant open spaces, and interconnecting mesoporous were prepared via electrodeposition method and further annealing process, respectively. The as-obtained materials with unique hierarchical structures offer a large electrochemical active area, resulting in a fast ion transportation (OH- in SCs and Li+ in LIBs) electrolyte immersion, as well as provide effective pathways for electron transport. Thus, the as-prepared Ni-Mo-Co triple hydroxides and oxides electrodes exhibit a high specific capacitance /capacity (3074 F g-1 at 2 A g-1 in SCs and 1132.31 mA h g-1 at 0.2 A g-1 in LIBs), remarkable rate performance, as well as long-term cyclability in SCs and LIBs, respectively. Also, the effect of composition of trimetallic hydroxides on SCs performance have been studied, and the performance have been optimized by tuning the feeding ratio of Ni, Mo, and Co. It is found that supreme performance was achieved when feeding ratio Ni/Mo/Co (1/1/0.4)

A comparison of online electrochemical spectroscopy impedance estimation of batteries

This paper compares methods of undertaking on-line electrochemical impedance spectroscopy that have been published in literature. This work describes the different published methodologies and sorts these into categories. The paper looks at the theoretical analysis of the circuits and control techniques and follows up with simulation and/or experimental studies of these methods. This work focuses on battery systems

State of Charge Estimation for Rechargeable Batteries Based on the Nonlinear Double-Capacitor Model

State of charge (SOC) estimation plays a foundational role in advanced battery management systems, having attracted much attention in the past decade. It is widely acknowledged that the accuracy of SOC estimation largely depends on the accuracy of the selected model. In this thesis, SOC estimation methods are developed based on the nonlinear double-capacitor (NDC) model, a novel equivalent circuit model that is distinctly capable of simulating the charge diffusion inside an electrode of a battery and capturing the battery’s nonlinear voltage behavior simultaneously. With improved predictive accuracy, the NDC model provides a new opportunity for enabling more accurate SOC estimation. With this motivation, the well-known extended Kalman filter (EKF) and unscented Kalman filter (UKF) are utilized to perform SOC estimationbased on the NDC model. The EKF is desirable here as it leads to efficient computation, straightforward implementation, and good convergence in its application to the NDC model, which is low-dimensional and governed by linear dynamics along with nonlinear output. The UKF is another popular version of the Kalman filter that belongs to the sigma-point filter family, and provably offers second-order accuracy under certain conditions, contrasting with the first-order accuracy of the EKF. The proposed SOC estimation methods are validated through simulations and experimental data under various conditions, showing significant accuracy as well as robustness to different levels of initialization error and noise

A STUDY OF THE LITHIUM IONIC CONDUCTOR Li\u3csub\u3e5\u3c/sub\u3eLa\u3csub\u3e3\u3c/sub\u3eTa\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e12\u3c/sub\u3e: FROM SYNTHESIS THROUGH MATERIALS AND TRANSPORT CHARACTERIZATION

The ionic conductivity of the lithium ionic conductor, Li5La3Ta2O12, is studied in an attempt to better understand the intrinsic bulk ionic conductivity and extrinsic sample dependent contributions to the ionic conductivity, such as grain boundary effects and the electrode-electrolyte interface. To characterize the material, traditional AC impedance spectroscopy studies were performed as well novel in-situ nanoscale transport measurements. To perform the nanoscale measurements, higher quality samples were required and new synthesis techniques developed. The results of these new synthesis techniques was samples with higher densities, up to 96% of theoretical, and slightly higher room temperature ionic conductivity, 2x10^−5 S/cm. By combining the AC impedance spectroscopy results and in-situ nanoscale transport measurements from this study and prior reported results, as well as introducing models traditionally used to analyze supercapacitor systems, a new interpretation of the features seen in the AC impedance spectroscopy studies is presented. This new interpretation challenges the presence of Warburg Diffusion at low frequencies and the offers a new interpretation for the features that have been traditionally associated with grain boundary effects

Master of Science

thesisAn increase in the demand for clean and sustainable energy storage with a high power density, along with a long cyclic life time has made supercapacitors an emerging energy storage device. However, one of the main challenges of today's world is to develop energy storage devices which are environmental friendly, cost effective, and which posses an excellent storage capacity. Therefore, this thesis presents the experimental results of utilizing nickel nanoparticle impregnated carbonized wood as a potential electrode material for supercapacitor applications. The electrode was synthesized by carbonizing the nickel nitrate impregnated wood at 900oC for an hour. The concentration of nickel nanoparticles in the carbonized wood was varied by changing the concentration of nickel nitrate solution. The surface morphology and the structure of the electrodes as prepared were studied by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). Electrochemical characterization such as Cyclic Voltammetry showed the presence of peaks indicating a psuedocapacitive behavior of the electrode. The Galvanostatic charge-discharge measurements showed nonlinear charge-discharge curves with changes in the slope. From the electrochemical measurements, it is observed that the electrode material exhibited a specific capacitance of 3616 F/g and a power density of 30 kW/kg along with an excellent capacitance retention of greater than 80% after 6000 charge-discharge cycles. These results indicate that the nickel nanoparticle impregnated carbonized wood could be one of the potential electrode materials for supercapacitor applications

An Economical Model Development for a Hybrid System of Grid Connected Solar PV and Electrical Storage System

Energy sources management is one of the most important concern in the recent decades. There are finite amount of non-renewable energy sources and one day they will run out if they have been used as primary sources of energy. Renewable energy sources have been significantly reduced the environmental effects. For most of them the source of energy is non-depletable. One of the concerns associated with renewable resources is uncertainty or unavailability. Energy Storage Systems (ESSs) can help to have more reliable and more efficient systems by adjusting the charge and discharge time and rate. In this study, an economic model is developed for a hybrid system of grid-connected solar photovoltaic, Compressed Air Energy Storage (CAES), and batteries. PV generation depends on irradiance and it is intermittent in nature. CAES can store energy in larger amounts and for longer periods than other storage systems and can offer lower price for stored energy. Batteries are integrated with CAES in this model mainly for lower demand and shorter periods. The presented model is a non-linear model and it’s been transformed to a linear model in this study. Optimal planning for generation and storage is derived based on the developed model for each day by using operation research techniques to maximize the value of energy which carried over the time. The results are different for each period and are highly dependent on the load demand. The results show that using solar PV panels coupled with energy storage systems increase the efficiency and reliability of the system. In addition to that, efficient use of energy storage system have a great impact on the final prices of electricity since electricity prices in low peak demand periods is lower than high peak periods