The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

Thermal runaway caused fire and explosion of lithium ion battery

Lithium-ion batteries are well-suited for fully electric and hybrid electric vehicles due to their high specific energy and energy density relative to other rechargeable cell chemistries. However, these batteries have not been widely deployed commercially in these vehicles yet due to safety, cost, and poor low temperature performance, which are all challenges related to battery thermal management. In this paper, a critical review of the available literature on the major thermal issues for lithium-ion batteries is presented. Specific attention is paid to the effects of temperature and thermal management on capacity/power fade, thermal runaway, and pack electrical imbalance and to the performance of lithium-ion cells at cold temperatures. Furthermore, insights gained from previous experimental and modeling investigations are elucidated. These include the need for more accurate heat generation measurements, improved modeling of the heat generation rate, and clarity in the relative magnitudes of the various thermal effects observed at high charge and discharge rates seen in electric vehicle applications. From an analysis of the literature, the requirements for lithium-ion thermal management systems for optimal performance in these applications are suggested, and it is clear that no existing thermal management strategy or technology meets all these requirements.

https://iopscience.iop.org/article/10.1149/1.3515880/pdf

A Critical Review of Thermal Issues in Lithium-Ion Batteries

Due to increasing concerns about global warming, greenhouse gas emissions, and the depletion of fossil fuels, the electric vehicles (EVs) receive massive popularity due to their performances and efficiencies in recent decades. EVs have already been widely accepted in the automotive industries considering the most promising replacements in reducing CO2 emissions and global environmental issues. Lithium-ion batteries have attained huge attention in EVs application due to their lucrative features such as lightweight, fast charging, high energy density, low self-discharge and long lifespan. This paper comprehensively reviews the lithium-ion battery state of charge (SOC) estimation and its management system towards the sustainable future EV applications. The significance of battery management system (BMS) employing lithium-ion batteries is presented, which can guarantee a reliable and safe operation and assess the battery SOC. The review identifies that the SOC is a crucial parameter as it signifies the remaining available energy in a battery that provides an idea about charging/discharging strategies and protect the battery from overcharging/over discharging. It is also observed that the SOC of the existing lithium-ion batteries have a good contribution to run the EVs safely and efficiently with their charging/discharging capabilities. However, they still have some challenges due to their complex electro-chemical reactions, performance degradation and lack of accuracy towards the enhancement of battery performance and life. The classification of the estimation methodologies to estimate SOC focusing with the estimation model/algorithm, benefits, drawbacks and estimation error are extensively reviewed. The review highlights many factors and challenges with possible recommendations for the development of BMS and estimation of SOC in next-generation EV applications. All the highlighted insights of this review will widen the increasing efforts towards the development of the advanced SOC estimation method and energy management system of lithium-ion battery for the future high-tech EV applications.

A review of lithium-ion battery state of charge estimation and management system in electric vehicle applications: Challenges and recommendations

Critical review of the methods for monitoring of lithium-ion batteries in electric and hybrid vehicles

With the development of electric drive vehicles (EDVs), the state-of-charge (SOC) estimation for lithium-ion (Li-ion) batteries has become increasingly more important. Based on the analysis of some of the most popular model-based SOC estimation methods, the proportional-integral (PI) observer is proposed to estimate the SOC of lithium-ion batteries in EDVs. The structure of the proposed PI observer is analyzed, and the convergence of the estimation method with model errors is verified. To demonstrate the superiority and compensation properties of the proposed PI observer, the simple-structure RC battery model is utilized to model the Li-ion battery. To validate the results of the proposed PI-based SOC estimation method, the experimental battery test bench is established. In the validation, the urban dynamometer driving schedule (UDDS) drive cycle is utilized, and the PI-based SOC estimation results are found to agree with the reference SOC, generally within the 2% error band for both the known and unknown initial SOC cases.

/pdf/the-state-of-charge-estimation-of-lithium-ion-batteries-4ab07qcl0t.pdf

The State of Charge Estimation of Lithium-Ion Batteries Based on a Proportional-Integral Observer

Three-dimensional thermal finite element modeling of lithium-ion battery in thermal abuse application

A new method to estimate the state of charge of lithium-ion batteries based on the battery impedance model

The intelligent optimization method for designing fractional order PI/sup /spl lambda//D/sup /spl delta// controller (FOPID) based on genetic algorithms is presented in this paper. Fractional calculus can provide new and good performance extension for FOPID because of the arbitrary order of fractional calculus. However, the difficulties of designing FOPID controllers increase. FOPID controllers' parameters are composed of proportional constant, integral constant, derivative constant, derivative order and integral order, whose design is more complex than that of conventional integer order PID controller. The optimization design process based on genetic algorithms is analyzed in detail in this paper, in which the optimization performance target is the combination of ITAE and control input, the numerical simulation of FOPID controllers uses the method of Tustin operator and continuous fraction expansion. Simulation results show the proposed method is highly effective.

Binggang Cao

Papers

The State of Charge Estimation of Lithium-Ion Batteries Based on a Proportional-Integral Observer

Three-dimensional thermal finite element modeling of lithium-ion battery in thermal abuse application

A new method to estimate the state of charge of lithium-ion batteries based on the battery impedance model

Optimization of fractional order PID controllers based on genetic algorithms

Component sizing optimization of plug-in hybrid electric vehicles